BIOLOGY 1
STANDARD 4.0
LESSON 4.3 LAB
PRINT OUT THIS LESSON BEFORE CONTINUING IN ORDER TO
FOLLOW THE DIRECTIONS AND COMPLETE THE ASSIGNMENT.
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The student will investigate the concepts of genetics and
heredity, different methods of reproduction, patterns of
inheritance, and genetic disorders; as well as, explore
and evaluate the DNA technologies from
both a scientific and ethical perspective.
Standard 4.2 – Understand the relationship between probability and genetic
research
Lab on Genetic Probability
Introduction: Scientists use a grid-like tool (Punnett Square) to
make predictions about various genetic problems. The Punnett
Square shows only the probability of what might occur and not the
actual results. Probability is the chance of something occurring. If
one wants to flip a coin 100 times, since there are 2 sides to the
coin, he would expect 50 heads and 50 tails. If he flips the coin 100
times, he may actually get 60 heads and 40 tails. Prediction is one
thing, and actually getting the predicted results is another. The
Punnett square only shows the chances of what might occur each
time the event is under taken.
Objective: In this investigation you will use a Punnett square to
predict the possible genotypes and phenotypes and their ratios
from a monohybrid cross.
Materials: 2 pennies
Procedure:
1.Each penny represents a heterozygous parent Gg x Gg.
2. Diagram a punnett square to predict what the possible offspring
of these two parents would look like.
Genotype ratio:
______________________________________________
Phenotype
ratio:______________________________________________
You will now perform an “experiment” to determine if what you
predict is always what you get in reality.
3. The head side on the coin represents the dominant gene for(G)
green and the tail side of the coin represents the recessive allele
(g) yellow.
4. At the same time, toss both coins representing the gametes. The
only possibilities that can be made from this are:
GG(heads-heads) Gg,(heads-tails) gg (tails-tails). GG is
homozygous green, Gg is heterozygous green, and gg is
homozygous yellow. Record the resulting combination in the data
sheet at the bottom of the page.
5. Toss the coins 29 more times and record results.
Data Table
Trial
1
Offspring's
Genotype
3456788888888
Offspring's Phenotype
3456788888888
2
3456788888888
3456788888888
3
3456788888888
3456788888888
4
3456788888888
3456788888888
5
3456788888888
3456788888888
6
3456788888888
3456788888888
7
3456788888888
3456788888888
8
3456788888888
3456788888888
9
3456788888888
3456788888888
10 3456788888888
3456788888888
11 3456788888888
34345678888888856788888
888
12 3456788888888
34345678888888856788888
888
13 3456788888888
33456788888888456788888
888
14 3456788888888
3456788888888
15 3456788888888
3456788888888
16 3456788888888
3456788888888
17 3456788888888
3456788888888
18 3456788888888
3456788888888
19 3456788888888
3456788888888
20 3456788888888
3456788888888
21 3456788888888
3456788888888
22 3456788888888
3456788888888
23 3456788888888
3456788888888
24 3456788888888
3456788888888
25 3456788888888
3456788888888
25 3456788888888
3456788888888
27 3456788888888
3456788888888
28 3456788888888
3456788888888
29 3456788888888
3456788888888
30 3456788888888
3456788888888
Summary:
1. What is the dominant trait? ______________.
2. How do we know it is dominant?
_____________________________________________________
__________________
3. Which one is the recessive trait? ________________.
4. What are the genotypes of the parents?
_____________________________________________________
_________________
5. What are the phenotypes of the parents?
_____________________________________________________
_________________
6. Fill in the Punnett square below using the parents given in the
procedure.
Male
Female________
X
_________
__
ssssssssssssssssssssssssssssss
ssssssssssssssssssssssssssssss
sssssssssss
ssssssssssssssssssssssssssssss
sssssssssss
ssss
7. What is the genotypic ratio? ____________________.
8. What is the phenotypic ratio? ____________________.