Los Alamitos High School
Science Department
Biology
Laboratory
Manual
Fall Semester
Biology Laboratory Manual – Fall Semester
This manual is the result of the collective work of the Biology science faculty at Los Alamitos High School.
Table of Contents
SAFETY IN THE LABORATORY .............................................................................................. 3
Microscopes: Introduction to the World of Biology ...................................................................... 5
Enzyme Lab .................................................................................................................................... 9
Identifying Macromolecules Pre-Lab........................................................................................... 13
Identifying Macromolecules Lab ................................................................................................. 15
Cell Exploration ........................................................................................................................... 19
Photosynthesis .............................................................................................................................. 23
Counting Leaf Stomata................................................................................................................. 27
Oodles of DNA............................................................................................................................... 31
Determining Phase Time in the Cell Cycle .................................................................................. 35
Monster Genetics .......................................................................................................................... 41
Human Genetics ........................................................................................................................... 47
2
SAFETY IN THE LABORATORY
The science laboratory is a safe place to experiment if you are careful. You must assume responsibility
for the safety of yourself and your neighbors. The following are some safety rules to help guide you in protecting
yourself and others from injury in the laboratory.
1.
The science laboratory is to be used for serious work. No horse-play is allowed at any time.
2.
Do not perform experiments that are unauthorized. Always obtain your teacher’s permission.
3.
Study your lab assignment before you come to the lab. If you are in doubt about any procedure, ask your
teacher for help.
4.
Safety goggles should be worn whenever you work in the lab.
5.
Use the safety equipment provided for you. Know the location of the fire extinguisher, fire blanket, and
the first aid kit. Know how each piece of equipment operates.
6.
Report any accident, injury, or incorrect procedure to your teacher at once.
7.
If you spill acids or any other corrosive chemicals, wash it off immediately with a large amount of water.
If you get a chemical in your eye, wash with water for 5 minutes. If you spill chemicals on the chemical
supply cart, clean them up immediately.
8.
Never taste any chemical substance unless you are directed specifically by your teacher to do so.
Absolutely no eating in the lab!
9.
Smother fires with a towel. If clothing should catch fire, smother it with a blanket or coat, or stop, drop
and roll.
10. Remove stoppers from reagent bottles carefully. Never set a stopper down on the chemical supply cart.
3
11. Handle chemicals carefully. Check the label of all bottles before removing the contents. Do not return
unused chemicals to reagent bottles.
12. Keep combustible materials away from open flames. (Some combustible materials are alcohol, carbon
disulfide, and acetone.)
13. When heating a substance in a test tube, be careful not to point the mouth of the test tube at another person
or yourself. Always use a test tube holder to heat a test tube, never your hands! Never heat a stoppered
test tube.
14. Use caution and the proper equipment to handle hot glassware. Cool glass looks the same as hot glass.
15. Place broken glass and solid substances in designated containers. Keep insoluble waste material out of
the sink.
16. Long hair should be tied back. Avoid wearing clothing with loose sleeves as it may catch fire.
17. Tell the teacher if your laboratory equipment is not in working order. Do not try to fix it yourself.
18. If you break a piece of lab ware, inform the instructor immediately.
19. Use a fire extinguisher to put out flammable liquid fires.
20. Before you touch an electrical outlet, make sure that your fingers are dry.
21. Do not borrow other people’s lab equipment. Use only the equipment at your station and that provided
by the teacher.
22. Wash all chemical spills with water to remove them from skin.
23. Do not put trash into sinks or in lab drawers.
24. Wash hands before leaving the lab.
4
NAME _________________________________________________________________PER _______ DATE ______________
Microscopes: Introduction to the World of Biology
Purpose: To learn the mechanics of how to complete a lab, to understand the proper usage of the
microscope
Materials: Compound Microscope
Prepared e slide
Prepared silk fiber slide
Diatoms slide
Tick slide
Procedure:
Part 1: Introduction to the compound microscope
1. Place the letter e slide on the stage as if you were reading the letter. Make the certain that the
low power (red 100X) objective is in the position.
2. Lower the stage as low as it will go. While looking in the ocular, raise the objective slowly until
the letter is in focus.
3. Draw the letter e using all three objectives exactly as you see it through the microscope. To go
to high power, it is essential that you center the letter and change your objective without
moving the stage. The field of view is very small in the high power. You will only see a part of
the e.
Scanning
Red=40X
Low
Yellow=100X
High
Blue=400X
Part 1 Questions
1. What did you notice about the image of the letter e while using the microscope?
2. What happens to the field of view as you go to higher power objectives?
3. Why should you not use the coarse adjustment knob with the high power objective?
5
Part 2: Depth
1. Place the prepared slide of the silk threads on your microscope stage,
2. Center the threads so that the crossing of the threads are in the middle of your field of view.
3. Draw the threads under 100x (yellow) and 400x (blue) in color.
LOW
High
Yellow=250X
Blue=650X
Part 2 Questions
1. What do you notice about the resolution of the threads as you move the high power objective
up and down?
2. Can you see all three colors in the center of the threads at the same time? Why or Why not?
Part 3: Looking at Diatoms
1. Using the prepared slide of diatoms (tiny sea creatures) select 5 diatoms of different shapes
and draw them using the 250X (yellow) and 650X (blue) objectives.
LOW
Yellow=100x
High
Blue=400x
6
Part 4: Looking at a tick
1. Using the prepared slide of a tick draw as many details as you can under the low power
LOW
Red = 40x
Conclusion Questions:
1. What is the magnification of the compound microscope eyepiece (ocular)?
_______________________________________
2. What is the total magnification of the three objectives?
Red________
Yellow__________ Blue___________
3. What is the purpose of the diaphragm of your microscope and where is it located?
4. How should you carry the microscope?
5. Using your book, explain the meaning of the following words:
a. Compound light microscope=
b. Electron microscope=
c. Resolution=
d. Transmission electron microscope (TEM)=
e. Scanning electron microscope (SEM)=
7
Rules for use of the Microscope
1. Always carry the microscope with TWO hands: one hand on the base and one on
the arm.
2. Remove cover and place it next to your microscope or fold it and place it under
your scope.
3. Plug the microscope in on the front of your desk.
4. Always begin by using the lowest power (red 100X)
5. Lower the stage with the coarse adjustment knob.
6. Place the slide on stage, raise until slide is in focus.
7. You may change objectives at this time. Do not touch focus knobs. Use only fine
adjustment knob with the blue (650X) objective.
8. After completion of microscope work.
a. Return objectives to RED
b. Remove slide
c. Turn light off
d. Wind power cord around clips
e. Replace cover
f. Return to proper place
8
NAME ________________________
PER _______ DATE ____________
Enzyme Lab
PURPOSE:
You are a research assistant which is testing enzyme activity in various body tissues. You developed a simple
test to measure the effect of concentration and temperature on enzyme activity and reaction rate (the speed of a
chemical reaction). Your results and data are below.
BACKGROUND:
Enzymes are proteins that speed up the rate of chemical reactions that would naturally occur slowly. The
enzyme may be altered but it is not destroyed our used up by the reaction. You have hundreds of different
enzymes in each of your cells. Each enzyme is responsible for one particular chemical reaction.
Hydrogen peroxide (H2O2) is a chemical used to treat wounds because it kills cells, both bacteria and even
human. H2O2 is also produced as a waste product in all of your cells. The enzyme catalase, is responsible for
breaking down the H2O2 into water and oxygen. The reaction is below.
Catalase
2 H2O2
2 H2O + O2
Catalase is also found in many plants such as potatoes. This enzyme activity is responsible for turning potatoes
brown. We can use potatoes as a source of catalase to break down H2O2.
PROCEDURE:
A. Enzyme activity
1. Label two beakers, one “A” and one “B”.
2. Place one cube of potato in each of the 50-mL beakers.
3. Into beaker A, add 15-mL of water. Into beaker B add 15-mL of 1.5% H2O2.
4. Record your observations in the data table.
TREATMENT
BEAKER A (water added)
BEAKER B (H2O2 added)
Enzyme Activity
1. How will you know if the enzyme is active and working when you complete the next treatments?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
9
B. pH
1. Keep your beakers labeled “A” and “B”.
2. Place one cube of potato in each of the beakers.
3. Into beaker A add 5-mL of water and into beaker B and 5-mL of H2SO4.
4. Wait 20 seconds.
5. Add 15-mL H2O2 to both beakers.
6. Record your observations in the data table.
TREATMENT
BEAKER A
BEAKER B
(water and H2O2 added)
(H2SO4 and H2O2 added)
pH
2. Based on your observations, changes in pH increases/decreases enzyme activity (circle one).
3. REAL LIFE APPLICATION: Meat, including fish, is mostly protein. When people prepare sushi
or ceviche it is often mixed with lemon juice, an acid. Explain how this might make the fish safe to
eat “raw.” Be sure to cite evidence from your lab.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
C. Temperature
1. Keep your beakers labeled “A” and “B”.
2. Place one cube of room temperature potato in beaker A.
3. Heat one cube of potato for ____ seconds and place in beaker B. USE CAUTION! Potato may be hot.
4. Add 15-mL of H2O2 to both beakers..
5. Record your observations in the data table.
BEAKER A
BEAKER B
TREATMENT
(Room Temperature)
(Heated Potato)
Temperature
4. Based on your observations, changes in temperature increases/decreases enzyme activity (circle
one).
5. REAL LIFE APPLICATION: Stingray venom is a protein based poison. Your friend gets stung at
the beach. Based on you observations, what recommendations do have to reduce the effects of the
venom? Be sure to cite evidence from your lab.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
10
ANALYSIS Answer in complete sentences
1. Define enzyme (hint: use background information). _________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
2. What enzyme were we using in this lab? ___________________________________________________
___________________________________________________________________________________
3. Where is this enzyme located? ___________________________________________________________
___________________________________________________________________________________
4. What does this enzyme do in the presence of H2O2 (hydrogen peroxide)? ________________________
___________________________________________________________________________________
5. How did you know if the enzyme was working? ____________________________________________
___________________________________________________________________________________
What was the gas in the bubbles? _______________________________________________________
6. What effect did adding the acid (H2SO4) have on the enzyme activity? __________________________
___________________________________________________________________________________
a. What did you see or not see? ______________________________________________________
b. Describe a possible explanation for your observations. _________________________________
______________________________________________________________________________
7. What effect did changing the temperature have on the enzyme activity? _________________________
___________________________________________________________________________________
a. What did you see or not see? ______________________________________________________
_____________________________________________________________________________
b. Describe a possible explanation for your observations. __________________________________
______________________________________________________________________________
11
12
NAME _________________________________________________________________PER _______ DATE ______________
Identifying Macromolecules Pre-Lab
1. What does a “positive test” mean? _________________________
_______________________________________________________
Day 1
Macromolecule or substance
Name of test or how you are
being tested for
testing for the substance
How will you know the substance
is present? What do you expect to
see in a positive test?
13
14
Identifying Macromolecules Lab
DAY I:
Follow the steps below and record your observations for
each of the test tubes in the following procedures.
NAME __________________________
PER _________ DATE ____________
Before you begin label your test tubes A and B (near the lip of the test tube).
A. Simple Carbohydrate Test I (sugar) and Test II
You can test for the presence of simple sugars and also the relative quantity of sugar in a substance.
You will do the following procedure twice. You will test 2 glucose solutions, I and II.
1. Place 5 drops of glucose in test tube A and 5 drops of water in test tube B.
2. Add five drops of Benedict’s solution to each test tube. Using the test tube holder place the
test tube in the hot water bath.
3. Observe a color change (after about 2 minutes) and record your observations in the data table.
4. Wash out the test tubes.
B. Complex Carbohydrate Test (starch)
1. Place 5 drops of starch solution into test tube A and 5 drops of water into test tube B.
2. Add three drops of Iodine into each test tube. Observe a color change and record your
observations in the data table.
3. Wash out the test tubes.
C. Protein Test
1. Place 5 drops of the albumin (protein) solution in to test tube A and 5 drops of water into test
tube B.
2. Add 3 drops of Biuret’s solution to each test tube. Observe a color change and record your
observations in the data table.
3. Wash out the test tubes and set in the rack to dry.
DATA TABLE FOR PART I
In the data table below, record your observations and color changes for each of the test tubes in Part I of
“Identifying Macromolecules”.
Simple
Carbohydrate
Test I
Simple
Carbohydrate
Test II
Complex
Carbohydrate
Test
Protein Test
Agent Tested
(A)
Water
(B)
QUESTIONS:
1. Briefly explain the purpose for using water in test tube B in Part I.
15
2. What does a positive test (macromolecule is present) look like for a:
a.
b.
c.
d.
simple carbohydrate test I:
simple carbohydrate test II:
complex carbohydrate test:
protein test:
_________________________
_________________________
_________________________
_________________________
3. What macromolecules did we not test for in this investigation?
4. Why did we not test for nucleic acid?
5. Each of the macromolecules is considered an organic compound. What does that mean?
6. What monomer is each of these macromolecules made up of?
a. Carbohydrate:
b. Nucleic Acid:
c. Protein:
d. Lipid:
_______________________________________________________________________________________________________________________
DAY 2:
Today you are going to test various solutions to determine what macromolecules they contain. You will
use the same procedures as yesterday.
Number your test tubes 1-4.
A. Simple carbohydrate test (sugar)
1. Place 5 drops of solution A into the test tube labeled “A” Repeat for solutions B and C. To a
fourth test tube add 5 drops of water.
2. Add 5 drops of Benedict’s solution to each test tube.
3. Swirl the contents and place in the hot water bath for 2-3 minutes.
4. Record your results as a positive test (with a “+”) or negative (with a “-“).
5. Rinse out the test tubes.
B. Complex Carbohydrates Test
1. Place 5 drops of solution A into the test tube labeled “A” Repeat for solutions B and C. To a
fourth test tube add 5 drops of water.
2. Put 1 drop of Iodine to each of the test tubes.
3. Record your results as a positive test (with a “+”) or negative (with a “-“).
4. Rinse out the test tubes.
C. Protein test
1. Place 5 drops of solution A into the test tube labeled “A” Repeat for solutions B and C. To a
fourth test tube add 5 drops of water.
2. Add 5 drops of Biuret’s solution to each test tube.
3. Swirl the contents and observe for no more than 1 minute and put your results in the data
table.
4. Record your results as a positive test (with a “+”) or negative (with a “-“).
16
DATA TABLE FOR PART II
Record an observation for color for the simple carbohydrate test. Determine whether the solution has a
low or high concentration based on the color seen. Indicate a positive test (macromolecule is present) in
the data table below by putting an “+” (present) OR a “-“ for a negative test in the space for complex
carbohydrate and protein.
Simple Carbohydrate Test
Complex
High or Low Carbohydrate
Color
Test
Concentration
Protein
Test
SOLUTION A
SOLUTION B
SOLUTION C
QUESTIONS:
1. List possible foods that match each solution based on your data. Give at least three choices per
solution.
a) Solution A:
b) Solution B:
c) Solution C:
2. Match each solution (A-C) with the most appropriate nutrition label provided.
SOLUTION ________
SOLUTION ________
SOLUTION ________
17
3. What solution would you recommend for a person to use post-exercise? Explain your choice.
4. Go to page 1039 of your textbook and read about diabetes.
a) What is diabetes?
b) If you were making a dietary plan for someone with diabetes, which solution (A-C) would you
recommend when their sugar count gets low? Explain your choice.
5. An enzyme is what type of macromolecule?
6. The liquid in your stomach is a pH of about 2. Which of
two enzymes in the graph would be active in the
stomach?
the
7. Milk of magnesia and Tums® are to be used when a
person has an upset stomach. They are also commonly
referred to as antacids. Explain the importance of using
antacids in relation to enzyme activity.
Answer the following questions using either your textbook (p59-60) or by watching the video at
http://ed.ted.com/lessons/what-is-fat-george-zaidan
8. What type of lipid is a fat?
9. What does it mean for a fat to be “saturated’?
10. What does it mean for a fat to be “unsaturated”?
11. Give an example of a food that contains saturated triglycerides and a food that contains unsaturated
triglycerides:
18
Cell Exploration
NAME _____________________________
PERIOD ______ DATE ________________
Part I. Exploring Living Cells
A. To begin, look at the slides provided and draw the specimen under high power. Label the cell as
animal, plant, or prokaryote.
TITLE: Plant Cell
TITLE: Animal Cell
TITLE: Prokaryote
(Label cell membrane,
(Label cell membrane,
(Label cell membrane
cell wall, cytoplasm,
cytoplasm, and
and cytoplasm)
and nucleus)
nucleus)
MAGNIFICATION __________
MAGNIFICATION __________
MAGNIFICATION __________
B. Using evidence from the cells you viewed, describe the characteristics, structures, or organelles that
differentiate the following cell types.
a) Prokaryote? ________________________________________________________________________________________
__________________________________________________________________________________________________________
b) Eukaryote? __________________________________________________________________________________________
__________________________________________________________________________________________________________
c) Animal cell? _________________________________________________________________________________________
__________________________________________________________________________________________________________
d) Plant cell? ___________________________________________________________________________________________
__________________________________________________________________________________________________________
19
Part II. Alien Application
You are a microbiologist sent on an expedition to study possible life on a newly discovered planet
XR9150. You have discovered a species of life. Upon initial investigation you conclude that it is likely a
unicellular organism. Cell structure is extremely important to the way a cell functions in its environment.
You isolate a single cell from this planet and using a microscope you make the following discoveries.
Draw a conclusion about how each structure is important to the alien cell and give evidence to
support your statement. Incomplete sentences will result in a deduction of 5 points.
1. It contains more lysosomes than a typical cell found on Earth.
a) What is the function of lysosomes?
b) What does this indicate about the cell’s environment?
2. The cell has a flagellum.
a) What is the function of a flagellum?
b) What does this indicate about the environment?
3. The cell has organelles similar to chloroplasts but instead of being green, they are purple.
a) What is the function of a chloroplast?
b) What does this indicate about the cell’s environment?
4. The cell has organelles that hold large amounts of water.
a) What organelles found in earth cells is this most like?
b) What does this tell you about the environment?
20
5. Based on the organelles and structures you identified, what type of cell is this alien species?
Explain your reasoning.
6. Based on your answer to number 5, what other organelles would you expect to see?
7. Sketch a diagram of the cell (below) through a microscope including all the organelles identified
in #1-4 and #6. Label EACH structure.
8. Describe the type of environment the cell lives in based on your observations. Explain your
reasoning.
9. Name the new species you discovered. Organisms are scientifically named based on binomial
nomenclature. It should consist of two identifiers, Genus species. (EX. The scientific name for a
black panther is Panthera onca.)
21
22
NAME _________________________________________________________________PER _______ DATE ______________
Photosynthesis
BACKGROUND:
Photosynthesis is the process of converting light energy into chemical energy that can be used by plants,
animals and other organisms (yes there are other organisms!). Photosynthesis is important not just
because of its role in energy transfer, but also because of the chemical products, oxygen for respiration,
and glucose, and the ultimate source of carbon for all the organic molecules that make up all organisms.
Photosynthesis can be summarized in the following reaction:
6 CO2 + 6 H 2 O + Light  C 6 H 12 O6 + 6 O2
1. Look at the equation for photosynthesis (above).
a) List the reactants.
b) List the products.
2. Summarize the procedures as the teacher executes in the front of the room.
a) What substances were added to the tubes?
b) Circle the substances in part a. that are involved in photosynthesis (reactants).
c) Explain the color change you see.
3. Fill in the chart below.
Molecule Present
CO2
O2
Color
yellow
pH
basic
4. What are the relative concentrations of CO2 and O2 in a solution that appears green?
DAY 1 PROCEDURES AND DATA
1. The teacher has three test tubes. Follow along carefully and record observations and make color
sketches of the test tubes.
Table 1
TEST TUBE #1 - Plant
TEST TUBE #2 – No Plant
TEST TUBE #3 – Plant with
Foil
23
2. Identify the relative pH and concentrations of CO2 and O2 in each test tube.
Test Tube #1:
Test Tube #2:
Test Tube #3:
3. In which test tubes do you expect photosynthesis to occur?
4. What would happen to the solution if you were to add O2?
5. Sketch what you expect the color of each of the test tubes to look like tomorrow. Explain your
predictions.
Table 3.
Color
EXPLANATION
Prediction
#1
#2
#3
DAY 2 PROCEDURES AND DATA
6. Sketch the final color change. Explain the colors you see in terms of reactants, products, and pH.
Table 4.
TEST TUBE
EXPLANATION
Color
#1
#2
#3
24
Data Analysis:
1. Which test tube contained the most oxygen? Cite with evidence from the lab.
2. Why was there little to no color change in test tube #3? Explain what is happening in the test tube.
3. Which test tube served as the control? Explain why this test tube is the control.
4. Summarize how we tested for photosynthesis activity in this lab.
5. What could you do in the experiment to increase photosynthesis in each of the test tubes?
Application:
1. Science is often the inspiration for many superheroes and their powers. Using your knowledge of
photosynthesis and the chloroplast, give a scientific explanation for the Hulk’s green color and
impressive strength (Hint: strong muscles require a lot of energy).
Excerpts from “Keep Phosphorus Out of Our Waters,” by Dawn Pettinelli UConn Extension
“High levels of phosphorus in soil will not harm plants in your yard but it can adversely
(negatively) affect aquatic systems. Phosphorus stimulates the growth of algae and other
aquatic plants leading to eutrophication, or lack of oxygen, in the water. Eutrophication
occurs as the algae naturally die and decompose, lowering the oxygen level in the water and
causing fish and shellfish to die. As a result, water quality drops and the use of fresh water is
often restricted for drinking, recreation, fishing and other aquatic industries. In some states,
80 percent of water bodies are so affected by phosphorous contamination that they are unfit
for human recreation.”
2. How are phosphorous levels related to photosynthetic rates? Include evidence from the reading
to support your answer.
3. If we were to add phosphorus to the tubes in our experiment, how would our results change?
25
26
Name:
NAME _________________________________________________________________PER _______ DATE ______________
Counting Leaf Stomata
Introduction
Plants and animals both have a layer of tissue called
the epidermal layer. Plants have special pores called stomata
to allow passage of material. The stomata pores are
surrounded on both sides by jellybean shaped cells called
guard cells. Unlike other plant epidermal cells, the guard
cells contain chlorophyll to do photosynthesis. This allows
the cells to expand/ contract to open or close the stomata.
Guard cells are also closed when dehydrated. This keeps water in the plant from escaping. The opening or
closing of guard cells can be viewed in a microscope by adding different water concentration to the leaf tissue.
Most stomata are on the lower epidermis of the leaves on plants (bottom of the leaf). The number of stomata
on the epidermal surface can tell you a lot about a plant. Usually, a high concentration of stomata indicates
fast growth and wet climate. Lower concentrations of stomata indicate lower rates of photosynthesis and
growth or adaptations for dry weather.
Purpose:
To view and compare the stomata from the leaves of several species of plants.
Materials:
3 leaves (1 from 3 different species), compound light microscope, 3 microscope slides, clear nail polish,
transparent tape
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Obtain three leaves from different types of plants.
Pain a thick patch (at least one square centimeter) of clear nail polish on the underside of the leaf
surface being studies.
Allow the nail polish to dry completely.
Tape a piece of clear cellophane tape to the dried nail polish patch.
Gently peel the nail polish patch from the leaf by pulling on a corner of the tape and “peeling” the
fingernail polish off the leaf. This is the leaf impression you will examine.
Tape your peeled impression to very clean microscope slide. Use scissors to trim away any excess tape.
Label the slide with plant name.
Examine the leaf impression under a light microscope at 400x.
Search for areas where there are numerous stomata and where there are no dirt, thumb prints,
damaged areas, or large leaf veins. Draw the leaf surface with stomata.
Count all the stomata in one microscopic field. Record the number on your data table.
Repeat counts for at least three other distinct microscopic fields. Record all the counts. Determine an
average number per microscopic field.
From the average number/ 400x microscopic field, calculate the stomata per mm2 by multiplying by 8
Follow procedures 2-11 with the other leaves.
27
Data
Leaf 1
Leaf 2
Leaf 3
Name of Leaf
Drawing in 400x (with
several stomata)
Stomata in field 1
Stomata in field 2
Stomata in field 3
Average Stomata in field
Stomata/ mm2
Conclusion:
1.
Which leaf had the most stomata? Why do you think this was so?
2.
Explain, in detail, how guard cells open and close stomata?
3.
At what time of day would stomata be closed and why?
4.
Why does the lower epidermis have more stomata than the upper epidermis of a leaf?
5.
Define transpiration.
6.
What two gases move in and out of the leaf stomata?
28
7.
What does a larger number of leaf stomata indicate about the growing climate of that plant?
8.
Would you expect CAM plants to have as many stomata? Why or why not?
CAM= Crassulacean acid metabolism for plants in arid conditions.
29
30
Oodles of DNA
Background: Locked within the nuclei of cells lies the chemical of heredity- DNA! Surrounding the nucleus is a
phospholipid bilayer- a lipid can be broken with the use of a simple detergent. Once the membrane is broken, we can
take advantage of DNA’s polar nature to extract it from cells. DNA is attracted to alcohol. Alcohol can be used to
separate the DNA from a solution. Wheat germ cells have roughly 100 chromosomes. Thus, there is an enormous
amount of DNA that can be extracted!
Purpose: The purpose of this laboratory exercise is to extract DNA from the nucleus of wheat germ cells.
Problem: Relate the DNA extraction procedure to cellular structures.
Materials:
2 grams raw wheat germ
100 ml beaker
18 ml 99% isopropyl alcohol
glass stirring rod
1.5 ml liquid detergent (Joy)
30 ml 50-60 degree Celsius water
wood splint or applicator stick
watch or wall clock
graduated cylinder
analytical balance
eye dropper
Procedure:
Part 1:
1.
2.
3.
4.
5.
Place two grams of raw wheat germ in a 100ml beaker.
Add 30 ml of 50-60 degree Celsius tap water to the wheat germ.
Mix constantly for 3 minutes.
Add 1.5 ml (3 eye-droppers full) of liquid detergent.
Mix gently for 5 minutes.
Part 2:
6. Tilt beaker to a 45 degree angle and slowly pour 18 ml of alcohol so that it forms a layer on top of the
wheat germ/water/detergent solution. DO NOT MIX THE TWO LAYERS TOGETHER.
7. Let stand for three minutes. White, stringy, filmy DNA will begin to appear at the layer where the water
and alcohol meet.
8. Use a wooden stick to collect the DNA. You may collect more DNA by using the stick to lift the top of
the lower layer, water layer up into the bottom on the upper, alcohol layer.
31
NAME _________________________________________________________________PER _______ DATE ______________
Conclusion:
1. List the parts of the cell membrane.
2. Using this lab’s background information and your knowledge of cells and macromolecules, describe
how the following lab materials helped extract DNA.
a.
Detergent (soap) –
b.
Alcohol –
c.
Hot Water –
3. Why is it important to understand the molecules that make up the cell in order to extract the DNA?
4. Describe the appearance of the DNA you have extracted. How does it compare to the DNA we have
been studying? Was this surprising to you, explain.
5. DNA is made of four monomers. Attempt to write a 5-6 word sentence using only four different
letters.
6. The Discovery of DNA – an excerpt from Bill Bryson’s “A Short History of Nearly Everything”
“Victory fell to an unlikely quartet of scientists in England who didn’t work as a team, often weren’t on speaking terms,
and were for the most part novices in the field.
Of the four, the nearest to a conventional scientist was Maurice Wilkins, who had spent much of the Second World War
helping to design the atomic bomb. Two of the others, Rosalind Franklin and Francis Crick, had passed their war years
working on mines for the British government—Crick of the type that blow up, Franklin of the type that produce coal.
The most unconventional of the foursome was James Watson, an American prodigy who had distinguished himself as a
boy as a member of a highly popular radio program called The Quiz Kids (and thus could claim to be at least part of the
inspiration for some of the members of the Glass family in Franny and Zooey and other works by J. D. Salinger) and who
had entered the University of Chicago aged just fifteen. He had earned his Ph.D. by the age of twenty-two and was now
attached to the famous Cavendish Laboratory in Cambridge.
Crick, twelve years older and still without a doctorate, was less memorably hirsute and slightly more tweedy. In
Watson’s account he is presented as blustery, nosy, cheerfully argumentative, impatient with anyone slow to share a
notion, and constantly in danger of being asked to go elsewhere. Neither was formally trained in biochemistry.
a.
Based on the descriptions above, give a one sentence summary on the nature of each of the
four scientists.
32
Although Crick and Watson enjoy nearly all the credit in popular accounts for solving the mystery of DNA, their
breakthrough was crucially dependent on experimental work done by their competitors, the results of which were
obtained “fortuitously,” in the tactful words of the historian Lisa Jardine. Far ahead of them, at least at the beginning,
were two academics at King’s College in London, Wilkins and Franklin.
However, she (Franklin) did have the best images in existence of the possible structure of DNA, achieved by means of Xray crystallography, the technique perfected by Linus Pauling. Crystallography had been used successfully to map atoms
in crystals (hence “crystallography”), but DNA molecules were a much more finicky proposition. Only Franklin was
managing to get good results from the process, but to Wilkins’s perennial exasperation she refused to share her findings.
b.
The author uses the word fortuitously but places it in quotes. Fortuitous means lucky, or
fortunate, what might the author be implying by using quotations?
If Franklin was not warmly forthcoming with her findings, she cannot be altogether blamed. Female academics at King’s
in the 1950s were treated with a formalized disdain that dazzles modern sensibilities (actually any sensibilities).
However senior or accomplished, they were not allowed into the college’s senior common room but instead had to take
their meals in a more utilitarian chamber that even Watson conceded was “dingily pokey.” On top of this she was being
constantly pressed—at times actively harassed—to share her results with a trio of men whose desperation to get a peek
at them was seldom matched by more engaging qualities, like respect. “I’m afraid we always used to adopt—let’s say a
patronizing attitude toward her,” Crick later recalled. Two of these men were from a competing institution and the third
was more or less openly siding with them. It should hardly come as a surprise that she kept her results locked away.
c.
Assuming you were in a similar situation as Franklin, what would be your reaction to competing
scientists trying to use your research data?
That Wilkins and Franklin did not get along was a fact that Watson and Crick seem to have exploited to their benefit.
Although Crick and Watson were trespassing rather unashamedly on Wilkins’s territory, it was with them that he
increasingly sided—not altogether surprisingly since Franklin herself was beginning to act in a decidedly queer way.
Although her results showed that DNA definitely was helical in shape, she insisted to all that it was not. To Wilkins’s
presumed dismay and embarrassment, in the summer of 1952 she posted a mock notice around the King’s physics
department that said: “It is with great regret that we have to announce the death, on Friday 18th July 1952 of D.N.A.
helix. . . . It is hoped that Dr. M.H.F. Wilkins will speak in memory of the late helix.”
The outcome of all this was that in January 1953, Wilkins showed Watson Franklin’s images, “apparently without her
knowledge or consent.” It would be an understatement to call it a significant help. Years later Watson conceded that it
“was the key event . . . it mobilized us.” Armed with the knowledge of the DNA molecule’s basic shape and some
important elements of its dimensions, Watson and Crick redoubled their efforts. Everything now seemed to go their
way.
d.
Summarize Wilkins’ actions from the previous two paragraphs.
e.
How would you judge Wilkins’ actions? Use evidence from the reading to support your position.
33
It was known that DNA had four chemical components – called adenine, guanine, cytosine, and thiamine – and that
these paired up in particular ways. By playing with pieces of cardboard cut into the shapes of molecules, Watson and
Crick were able to work out how the pieces fit together. From this they made a Meccano-like model – perhaps the most
famous in modern science – consisting of metal plates bolted together in a spiral, and invited Wilkins, Franklin, and the
rest of the world to have a look. Any informed person could see at once that they had solved the problem. It was
without question a brilliant piece of detective work, with or without the boost of Franklin’s picture.
f.
Describe the shape or appearance of the model that Watson and Crick created.
Rosalind Franklin did not share in the Nobel Prize. She died of ovarian cancer at the age of just thirty-seven in 1958, four
years before the award was granted. Nobel Prizes are not awarded posthumously. The cancer almost certainly arose as a
result of chronic overexposure to X-rays through her work and needn’t have happened. In her much-praised 2002
biography of Franklin, Brenda Maddox noted that Franklin rarely wore a lead apron and often stepped carelessly in front
of a beam. “
g.
Wilkins, Watson, and Crick were awarded the Nobel Prize for the discovery of the structure of
DNA. If you were on committee for this decision, would you have made any changes in regards to the
recipients? Why or why not?
34
NAME _________________________________________ PER ______________ DATE
_________________
Determining Phase Time in the Cell Cycle
Do all phases of the Cell Cycle require the same amount of time for completion?
This question can be answered by counting the number of onion root tip cells in the four phases of mitosis and also
interphase. Many cells found in one specific phase indicate that a long period of time is required for completion of
that phase. Few cells found in a specific phase indicate a short period of time is required for completion of that
phase. Using this measure, you will analyze various aspects of the cell cycle stages.
In this investigation, you will:
 Count the number of cells in each of the phases of mitosis and in interphase.
 Compute the length of time in minutes needed to complete each phase.
 Compare data of the time needed for normal cells to complete each phase with that of abnormal cancer
cells.
MATERIALS
- Onion Root Tip Sample Diagram
- Calculator
-Colored pencils or markers
PROCEDURE
Part A
Locating and Counting Onion Cells in Various Phases of the Cell Cycle
1. Examine the “Onion Root Tip Section Diagram” which shows the portion of an onion root tip.
2. At high power, count and record the NUMBER OF CELLS IN EACH PHASE of the cell cycle in Table 1. Record this
data under the column labeled “First Area”.
3. Gather data from other tables or groups for “Second Area” and the “Third Area”.
TABLE 1. Cells counted using the Alium root tip.
PHASE
First Area
Second Area
Third Area
Total Number
of Cells in Each
Phase
(add all areas
together)
Time in
minutes
(see directions
under part B)
Interphase
Prophase
Metaphase
Anaphase
Telophase
TOTAL
35
Part B
Determining the Time Required for Each Phase of Onion Root Tip Cell Cycle
Assume that the number of cells in a phase is an indication of the time spent in that phase during mitosis. Time
spent in a mitotic phase and in interphase can be calculated if the total time for mitosis is known. Onion cells
require 12 hours (720 minutes) to complete mitosis (from interphase to interphase). The amount of time needed
for a phase can be calculated using the formula:
number of cells in a phase x 720 minutes = time spent in phase
total number of cells
For example:
If 109 cells were counted in metaphase and 980 total cells were counted, then
98 cells x 720 minutes = 72 minutes of time spent in metaphase
980 total cells
1. Calculate the time spent in each phase of the cell cycle using the data in column ‘Total Number’ and the math
formula above. Assume that the total time for mitosis is 720 minutes.
2. Record the calculated times in Table 1.
3. Show work and calculations below.
4. Which phase requires the longest time for completion?
Part C
Graphing the Time for the Cell Cycle of an Onion Root Tip Cell.
Using your data from Table 1 and the sectioned circle below, prepare a pie chart which shows the number of
minutes that onion cells spend in each phase of mitosis. The following suggestions may aid you in preparing your
graph.
1. Graph your data using the “Time in each Phase” column from Table 1 (the first table).
2. The circle is divided into 18 minute sections. Each section of the graph equals 18 minutes. If a phase is not
exactly 18 minutes long (or some interval close to a multiple of 18 minutes), approximate the position of the
line on the graph.
3. Shade each phase on your graph with colored pencils.
4. Identify each phase by shading the key to correspond with the shading on your graph.
For example:
If 72 minutes of time was spent in metaphase then 72/18= 4
You would color in 4 segments on the chart and label as “Metaphase”.
Show these calculations here.
36
GRAPH 1. Time in each phase.
1. Which phase takes up the most space on your graph?
2. Please look at figure 8-5 on page 155 of your textbook. How does your graph compare to the figure?
3. What does this tell you about the accuracy of the lab that we did? Support your answer with data from the lab.
TABLE 2. Time spent in each phase of the cell cycle in normal and cancerous chicken cells.
NORMAL CHICKEN STOMACH CELLS
CANCEROUS CHICKEN STOMACH CELLS
Time spent in each phase (min)
Time spent in each phase (min.)
Interphase
Prophase
Metaphase
Anaphase
Telophase
540
60
10
3
12
TOTAL
______________
1. The time spent in each phase has already been determined for you.
380
45
10
3
10
______________
37
a) The total time needed to complete one cell cycle in normal chicken cells is _________________ min.
b) The total time needed to complete one cell cycle in cancerous cells is _________________ min.
2. Based on the data provided in table 2, where is the problem in the cancer cells’ cycle?
Read the following passages and answer the questions that follow.
If you could observe the activity of the cells in adult chicken stomach tissue, you would find that cell cycle only
happens to maintain healthy tissue. In other words, a cell divides and becomes 2 cells when a pre-existing cell dies
off naturally. This is the normal way things happen in an adult organism – the total number of cells in an area of
tissue stays about the same. Hence, a cell dies and a new one is developed through the cell cycle (cell division) to
replace it. Let’s say that, on average, in healthy chicken stomachs there is at least one cell dying and a new one
produced every 625 minutes.
3. How often would a cancerous cell be generated?
A normal chicken stomach cells naturally die off and are replaced every 625 min. For reasons unknown, a single
functioning cancerous chicken cell develops among the normal ones, however it has a cell cycle time of 448 min.
Let’s also say that cancerous cells will die off at the same rate as normal cells are generated. In other words, the
cancerous cells will reproduce (divide) - even though no cancer cell has died off (every 448 minutes). Let’s assume
the number of cancer cell deaths equals the number of normal cells that die.
4. What kind of a problem related to cancer arises from this?
5.
There are 10,080 minutes in a week. How many cell cycles does each cell type complete a week?
For example, one Alium takes 720 minutes to complete one cycle. If there are 10,080 minutes in a week:
1 cycle___ x 10,080 minutes = 14 cycles/ week
720 minutes
week
Normal cell: _______________________
Do work below:
Cancer cell: _______________________
6. How many more cell cycles does the cancerous cell(s) go through one week after the cancer cell developed?
7. What is happening to the total cell count in the tissue area where the cancer cell developed?
38
Most women are shocked to find out that they have had their breast cancer for years before it was discovered.
Cancer growth is measured in doubling times. One doubling time is the amount of time that it takes for the mass of
cancer cells to double in size. The shorter the cell cycle, the faster the doubling time. It takes about 23 doubling
times to go from one cancer cell to become a large enough mass to be seen on a mammogram, and about 30
doubling times to become large enough to be felt as a lump, about one billion cells. Doubling times may be as short
as 10 days or as long as several years, depending on the cell cycle. Four months is the average doubling time for
most cancer cells. A cancer's doubling time is an indication of how fast it grows. The doubling time is very
important in determining the time course of the cancer. For example, a cancer first starts when a woman is 40. It is
a fast growing cancer with a doubling time of 2 months. It takes 46 months (2x23), or almost four years, before it is
large enough to be detected by a mammogram and 60 months, or five years, before she feels it. She is diagnosed
with cancer at age 44 or 45. If, on the other hand, she has a slow growing cancer with a doubling time of two years,
she would be 86 before it could be found on a mammogram and 100 before she could feel it. She probably would
die of other causes before she ever knew she had cancer. Carefully performed autopsy studies show undetected
invasive breast cancer in over 3% of women age 40 and older. Since most breast cancers grow at an intermediate
pace, usually the cancer has been present for 8-10 years before being discovered.
8. Summarize the significance of a cancer’s doubling time on detection and possible treatment.
39
40
NAME _____________________________________________________________________PER _______ DATE ___________________
Monster Genetics
REVIEW QUESTIONS:
Answer the following questions with your partner before you get started.
Heredity is the passing on of traits, or characteristics, from parent to offspring. The units of heredity are called
genes. Different versions of the same gene are called alleles. Genes are found on the chromosomes in a cell. The
combinations of genes for each trait occur by chance.
1. Where are genes located?
2. Do you have only one version of a gene? Explain.
When one allele in a pair is stronger than the other allele, the trait of the weaker allele is masked, or hidden. The
stronger allele is the dominant allele, and the allele that is masked is the recessive allele. Dominant alleles are
written as capital letters and recessive alleles are written as lowercase letters. If both alleles are different, the trait
is said to be heterozygous. The genetic makeup of an individual is known as its genotype. The observable physical
characteristics of an individual that are the result of the genotype are known as its phenotype.
3. Explain the difference between an organism that is said to be homozygous versus heterozygous.
4.
Describe the relationship between genotype and phenotype.
Sometimes alleles are neither dominant nor recessive. The result of such a situation is a blending of traits. It is also
possible that the traits can be equally expressed, or both dominant.
5. Identify a trait we have discussed that is expresses a) incomplete dominance and a trait that is b)
codominant.
In humans, the sex of an individual is determined by the particular combination of the two sex chromosomes.
Individuals that have two X chromosomes (XX) are females, whereas those with an X and a Y chromosome (XY) are
males.
6. Why is it that the man determines the baby’s gender and not the woman?
41
BACKGROUND:
Genetics is the field of biology that studies how characteristics are transmitted from parents to offspring. In this
lab activity you are a highly intelligent monster from an Earth-like planet called Druidia. One of the creatures that
inhabits this planet is called the Kremulak (Monstrousitus sargii). Your task is to try to repopulate your planet but
you need to study traits to ensure a diverse population. You and your partner will “reproduce” a monster.
PROCEDURE:
1. Assume you and your partner are both heterozygous for all twelve traits you will be studying. Choose one
partner to be the “mother” and one partner to be the “father”.
2. Reproduce your monster baby.
a) To determine the genotype for each trait listed, each partner flips his/her coin (heads represents dominant
allele; tails represents recessive allele).
b) Fill in the table below. There is one column for each partners resultant coin flip. You decide which partner
is the “first” coin and which partner is the “second” coin.
c) After you determine the genotype, get a key from the planet’s matchmaker (your teacher) and fill in the
phenotype for your baby. Please note which traits’ dominance.
3. Make your alien baby. You have paper models to color, cut, and assemble.
4. Answer the questions that follow.
42
The first row is an example and you do not have to use this as one of your characteristics.
TRAIT
(Heads, tails)
Body Shape (P,p)
FIRST COIN
SECOND
COIN
GENOTYPE
PHENOTYPE
Head shape (O,o)
Eye Shape (S,s)
Feet (W,w)
Legs (S,s)
Hair (A,a)
Hands (P,p)
Mouth (T, t)
Ear Shape (E,e)
Antenna* (S,s)
Eye Color* (R,r)
Arms* (Z,z)
Body Color ** (P,O)
Hair Color ** (P,G)
Gender
Wings--sex-linked (XW, Xw, Y)
* Incomplete Dominance
** Codominance
CONCLUSION:
1. Complete Punnett squares to predict what phenotypes and genotypes the next generation offspring would have
from a cross between the two monsters for the following traits. You will use the genotype of the other partners
at your table. Be sure to include a Punnett Square for each.
Eye shape Parental cross:
Possible resultant phenotypes:
Antenna
Parental cross:
Possible resultant phenotypes:
Hair color Parental cross:
Possible resultant phenotypes:
43
2. Explain how it might be possible that the baby monster would show traits that neither of the parents exhibited.
3. In humans, the sex of an individual is determined by the particular combination of the two sex chromosomes.
Individuals that have two X chromosomes (XX) are females, whereas those with an X and a Y chromosome (XY)
are males. Monster genetics works the same way. What percent chance do the male and female monsters have
of producing a male offspring? Explain your answer.
4. Below is a pedigree for a monster lineage. The analysis (shaded dark) indicates the monsters in the family tree
that have talons (recessive trait).
a) What is the genotype for individual 4?
b) What is the genotype for individual 12?
c) Individual number 9 has the genotype
Ww. How do we know this?
5. Do you think the baby monster could have some traits of the grandparents? Explain.
44
Genetic Trait Reference Sheet
Trait
Homozygous Dominant
Heterozygous
Homozygous Recessive
Body shape
PP= Peanut
Pp= Peanut
pp= triangle
Head shape
OO= Octagon
Oo= Octagon
oo= Rectangle
Eye Shape
SS=Straight
Ss=Straight
ss=Side eyes
Feet
WW= Webbed
Ww= Webbed
ww= Talon
Legs
SS=Short
Ss=Short
ss=Tall
Hair
AA=Afro
Aa=Afro
aa=straight
Hands
PP= Paw
Pp= Paw
pp= Claw
Mouth
TT=Teeth
Tt=Teeth
tt=snaggle tooth
Ear Shape
EE = Elephant
Ee = Elephant
Ee = Bunny
Antenna*
SS=short
Ss=medium
ss=tall
Eye Color*
RR= red
Rr= purple
rr= blue
Arms*
ZZ= zig zag
Zz= wavy
zz= straight
Body Color **
PP= Purple
PO= Purple and orange
stripes
OO = Orange
Hair Color**
PP=Pink
PG= pink with green
spots
GG= Green
Sex-linked Trait
Males
Wings
XWY= wings
XwY= no wings
Females
XW XW= wings
XW Xw = wings
XwXw= no wings
* Incomplete Dominance
** Codominance
45
46
Human Genetics
47
48
49
50
51