Objectives
• Students will explore the history of DNA
scientific knowledge by recreating a
pictorial timeline.
• Students will study the location & structure
of DNA
• Students will create Pneumonic devices to
remember base pairing
Today you need: textbook, pen or
pencil, paper for notes, markers to
share
• Bellwork: vocabulary!
• 1. DNA (deoxyribonucleic acid)R52
• 2. chromosome R48
• 3. chromatid R48
• 4. centromere R47
• 5. nucleotide R64
You need: notebook, pen or
pencil
• No bell work
• See me after we are done
taking notes if you missed
the test yesterday.
DNA
How do genes work? What are they made of,
and how do they determine the characteristics
of organisms?
In the middle 1900’s questions like these were
on the minds of biologists everywhere.
Gregor Mendel “Father of
Genetics” (1864)
Genetics – began the scientific
study of heredity.
Saw patterns in the traits passed
on by sweet pea plants
Where is DNA?
• In the nucleus of every cell of every living
thing (in chromosomes) or is floating in
bacteria
• Carried in the chromosomes.
Parts of the chromosome
(draw and label pic below)
The Components and Structure of DNA
• When scientists found out that the molecule
DNA was responsible for our genetics they
still were not satisfied.
• How could DNA or any molecule for that
matter have the ability to carry, translate,
copy, and be responsible for our heredity?
DNA(Dexoyribose Nucleic Acid)
• DNA is a long molecule made up of units called
nucleotides.(draw and label pic at bottom)
• Nucleotide is made up of three basic structures:
- a sugar
- a phosphate
- a nitrogen base
(d
Look to learn
• 1. What are you learning
today?
• 2. Why is it important?
• 3. How does it relate to what
you learned last?
Shape of DNA
• DNA is often called a “Double Helix” or a
“Twisted Ladder”
• All the 3 part nucleotides are linked
together into this chain.
The Backbone of DNA
• The “backbone”(the
sides of the ladder) of
DNA is made of up of
sugar & phosphate.
• The nitrogen bases
link in the middle
(make the steps of the
ladder)
Bases are linked by
hydrogen bonds
Nitrogenous Bases
• DNA’s nitrogenous bases are the letters of
the words which make up our genetic code.
• Adenine always connects with Thymine.
• Cytosine always connects with Guanine.
Together these bases make
up the steps of a ladder.
Nitrogenous Bases
The bases are always paired in the following way:
Amazing fact!!!!!!!
• These 4 bases create the code
for every living thing!!!
• Mix them up and you get a
bacteria…or an animal…or a
plant…or a mushroom….or a
monkey!!!
Adenine and Thymine
Guanine and Cytosine
DNA
•
DNA’s History
• Now that you know what DNA
is and what it is constructed,
how do you think it was found?
Chargaff’s Rule
• Discovered the how the
nitrogenous base were always
paired in the same way.
X-Ray Evidence
• In the early 1950’s a British scientist named
Rosalind Franklin began to study DNA.
• Just like anyone else that is curious Rosalind
wanted to see what she was studying, so she
literally to a picture of DNA with an X-ray.
The Double Helix
• At the same time that Franklin was continuing
her research, James Watson and Francis Crick
were trying to build a three-dimensional model
of the molecule.
• Watson and Crick used Rosalind’s picture to
figure out DNA’s puzzle and the solved what is
known as the double helix.
• DNA is a double helix in which two strands
are wound around each other. Each strand is
made up of a chain of nucleotides. The two
strands are held together by hydrogen bonds
between adenine and thymine and between
guanine and cytosine.
Let’s try some base pairing!
• Tortillas arroz con guacamole.
• Take another clueless guess.
• What bases would pair with the following?
• T_A_C_G_T_C_G_A_T
Draw, write or do a timeline
•
•
•
•
•
•
What are the advances attributed to each?
pages 216-222
1. Griffin 1928
2. Avery 1944
3. Hershey & Chase 1952
4. Watson & Crick 1954
Textbook work
• Page 223
• Answer question 1-6
Workbook
• Read 126-128
• Answer the 2 instant replay questions
• Answer 1-3 ON 128
Workbook
• Read 129 – 131
• Answer the instant replay question
• Answer 1-4 on 131
Structure of DNA Worksheet:
• 1. genetic code for all life, nucleus
• 2. twisted ladder ( phosphate & sugar on
sides, bases joined by hydrogen bonds in
middle)
• 3. double helix
• 4. sugar, phosphate & nitrogenous base
• 5. hydrogen bonds
DNA and RNA
•
•
•
•
•
•
•
1.2.3.(find in book) 288-289
4. double helix
5. Crick & Watson
6. hydrogen bonds
7. nucleotide
8. sugar & phosphate backbone
9. hydrogen _ like rungs
– Sugar/phosphate – side rails
• 10. 28%
You need: pen or pencil; sheet
from front
• You will work in pairs (2).
• This will be a quiz grade.
• Retests will be on the 29th & 30th in class
• If you want to retest, take the original test
and your answers…redo it and study it.
• The retest will be scrambled…so don’t
memorize the answers!!! Or it will be an
epic fail.