UNESSCO‐NIGERIA
A TECHNICAL & VOCATION
NAL EDUCA
ATION REVITTALISATION P
PROJECT‐PHA
ASE II NATTIONALL DIPLO
OMA IN SCIENCE LA
ABORA
ATORY TECHNO
T
OLOGY
GENETICS
S
COU
URSE CO
ODE: STB
B 221 YEAR 2
2‐ SE MESTER 2 PR
RACTICA
AL Version 1: Decemb
ber 2008 1 TABLE OF CONTENTS
PRACTICAL ONE (WEEKS 1&2) - Identification of nucleus in cell………….3
PRACTICAL TWO (WEEKS 3&4)- Mitotic cell division……………………..4
PRACTICAL THREE (WEEKS 5&6)-Meiotic cell division…………………..5
PRACTICAL FOUR (WEEKS 7&8)-Expression of dominant characters……..6
PRACTICAL FIVE (WEEKS 9&10)- Organisms used in genetic experiments..7
PRACTICAL SIX (WEEK 11)- Variations in seedlings………………………..8
PRACTICAL SEVEN (WEEKS 12&13)- Deviations from Mendelian……….. 9
inheritance.
2 PRACTICAL 1, WEEK 1&2 - IDENTIFICATION OF NUCLEUS IN CELL
AIM: To show the organelle in which the chromosomes (and genes) reside
MATERAILS: A medium size onion bulb, new razor blade, water in small plastic water bottle, 2
microscope slides with cover slips, a binocular microscope , stain /dye(e.g. iodine/ Benedict solution
or Fehlin’s solution)
PROCEDURE: Cut the onion bulb into 2 halves. Cut one of the halves into two halves again, using
razor blade. Remove a scaly leaf from one of the quarter cut, bend it backward until it breaks, peel
out a small piece of epidermal layer on a clean microscope slide with 1or2 drops of water. Cover
with a cover slip and view under the microscope, first with low power (X4) objective and then high
power (X10) objective and observe. Remove the slide from the microscope, uncover the cover slip,
add 1or 2 drops of stain provided and replace the cover slip. View again under the microscope using
X4 and X10 objectives .
EXERCISE:
1.
Draw 2-3 cells and label fully, as observed under the microscope.
2.
Give the functions of the organelles identified.
3.
Why is the nucleus regarded as the control center of the cell?
3 PRACTICAL 2, WEEK 3-4: MITOTIC CELL DIVISION
AIM: To show the behavior of chromosomes in stages of mitosis.
MATERIALS: Onion bulb seedlings in water culture, binocular microscope,2 microscope slides
with cover slips, stains / dyes, water in small water bottles, razor blade or scalpel, blotting /tissue
paper.
PROCEDURE: Cut 2-3 root tips [1 -2mm] onto a clean microscope slide and add 1-2 drops of
water. Gently macerate the root tips into thin squash, using the tip of a pen. Add 1-2 drops of stain
provided [e.g. iodine solution, Fehlin’s solution] and spread it out thinly /evenly on the slide. Cover
with cover-slip and observe under the microscope, first with X10 objective and then X40 objective
using oil immersion, observe under X100 objective.
EXERCISE:1. Draw the various shapes/structure of chromosomes as observed
2. Show the various types of chromosomes on the basis of their centromere position.
3. Show the various stages of the cell division as observed and write shorts notes on each stage
describing the behavior of chromosomes.
4 PRACTICAL III [WEEK 5-6]
TITLE:‐ Meitotic cell division AIM:‐ To show the behavior of chromosomes during meiosis I and II MATERIALS:‐ Prepared microscope slides of different stages of meiosis and a binocular microscope are provided. Alternatively, prepared projector slides of different stages of meiosis and a projector with the screen are provided. PROCEDURE:‐ connect the microscope or projector provided to the power source and operate. View the slides studiously and make short notes on each. EXERCISE:‐ 1. Draw and identify each of the stages observed. Label fully. 2. Briefly describe the behavior of chromosomes in each stage. 3. In a tabular form, describe the differences between meiosis I and II, with particular reference to chromosomal behavior. 5 PRACTICAL IV [WEEK 7-8]
TITLE:-Expression of dominant character.
AIM:-To identify the various degrees of dominance expression.
MATERIALS:- Field trip to an experimental farm in an Institute of Agricultural Research {IAR},
genetic corn, beakers {4}
PROCEDURE:- Visit farm fields grown with advance lines {pure breed} of maize or guinea corn
or cassava, or citrus or palm, etc. Take note of the uniformity and other observable characteristics.
Shell the genetic corn provided into a beaker. Count the white grains into another beaker. Do same
for the coloured grains. Record the counts accordingly.
EXERCISE:1. Mention any 3 observable features common to all the plants in the fields.
2. Mention any 3 observable features seldom observed in the fields.
3. Give reasons for observations in 1 and 2 above.
4. Find the ratio of white grains to coloured ones and explain the genetics involved.
6 PRACTICAL V [WEEK 9-10]
TITLE:-Organisms used in genetic experiments.
AIM:- To identify the various characteristics that qualify an organism for use in genetic
experiments.
MATERIALS:- Cultures of Drosophila [fruit fly ],Neurospora [fungus], hand or table lens, rotten
fruits[ eg .mango, sweet orange, guava],waste corn cob stalks.
PROCEDURE:- Cut the rotten fruits into halves each and expose them by the windows in the
laboratory. Observe daily for Drosophila colonization and observe the individuals in the culture of
Drosophila with the aid of a hand or table lens. Record the characters observed.
To generate a culture of Neurospora, expose moist corn cob stalks by laboratory corridors until fully
infested with Neurospora. Then observe with the hand lens for distinguishing characteristics.
EXERCISE:1.
List the contrasting features among the individuals in the Drosophila and Neurospora
cultures.
2. Give reasons why these two organisms are suitable for genetic experiments.
7 PRACTICAL VI [WEEK 11]
TITLE:- Variation in seedlings
AIM:- To identify genetic variations in a natural population of plants.
MATERIALS:- Seeds from a wild herbaceous Spp., nursery bed, or 20 planting pots, garden
soil, water, watering can, hoe or trowel.
PROCEDURE:- Raise seedlings from the wild seeds collected in a nursery bed or planting
pots {2-3 seedlings /pot}. As the seedlings grow, find out if the seedlings show phenotypic
variation.
Make a list of all variable characters.
EXERCISE:1. Give reasons why seeds were collected from wild plants instead of cultivated variety.
2. In a tabular form, list all the phenotypic variations observed under measurable {metric}
and non-measurable {non-metric} parameters.
3. Explain the genetic basis of these variations
8 PRACTICAL VII [WEEK 12-13]
TITLE:- Deviations from mendelian inheritance.
AIM:-To identify complete, partial and no dominance conditions in coat colour of mice.
MATERIALS:-Black male mouse, white female mouse[or vice versa], but ensure that the female is
not pregnant, mouse cage, mouse feed, water in drinking can and mouse litter.
PROCEDURE:- Keep the two mice[male and female] together in a cage and feed daily. At
maturity, they would mate and produce offspring. As they grow up, note and record the coat colours
of the offspring.
EXERCISE:1. What is the total number of the offspring produced?
2. What proportion of the offspring:
A.
Resemble the male parent,
B.
Resemble the female parent
C.
Share the male and female parents.
3. Explain the genetic bases of these coat colour distribution among the offspring.
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