1. Punnett Squares

2. Quick Review
The most important organelle in a eukaryotic cell is the ________. The nucleus has one job, and that is to store the ______.
nucleus
nucleus
DNA 2

3. Quick Review
DNA is packaged into a very long molecule called a _____________. When you talk about chromosomes you need to realize that you are talking about ______.
chromosome
DNA
Human Chromosomes 3

4. The sequence is what holds the information!
The instructions or __________ for making proteins are found in the ______. The information is carried in the _________________________.
blueprint
DNA
sequence of nitrogen bases

5. The combination of genes in a person is known as his/her __________.
The sequences of DNA that helps to create and regulate proteins are known as a ______.
This includes the sections of DNA used to create all 3 major types of ______.
The combination of genes in a person is known as his/her __________.
gene
RNA
genotype
messenger RNA
(mRNA)
transfer RNA
(tRNA)
ribosomal RNA
(rRNA)

6. Humans have ____ different types of chromosomes, and they have ___ of each type. This means that they have a total of ____ chromosomes in all. In humans, the first 22 pairs are called ___________, but the 23rd pair of chromosomes is called the _____ chromosomes. If a person has the karyotype XY, the person is a ______. If a person has the karyotype XX, the person is a ________. 23 2 46
autosomes
sex
male
female
male
female

7. Phenotype for Fur Color
Because every person has ___ copies of every gene, we name them using lowercase and capital letter to show how they interact. Because of how the sequences of DNA that create and regulate _________ production interact, we say that some of them are __________ while others are __________. What we mean has been illustrated below: 2
protein
dominant
recessive
Subject A
Subject B
Subject C
Genotype for Fur Color GG Gg gg
Phenotype for Fur Color
Gray Fur
White Fur

8. The genotype of these girls is what determines their phenotypes!
We name genes based on the __________ they create. We call the different versions of a gene ________. You would find the hair color gene in the same place for everyone, but some people have the _______ for blond hair and some people have the _______ for black hair. We call the physical appearance that results from the proteins the organism’s ____________.
proteins
alleles
allele
allele
phenotype
Photo by Bahar
Photo by Marc Davis
The genotype of these girls is what determines their phenotypes!

9. Phenotype for Fur Color
Dominant genes are always __________. This means that they always appear as the phenotype. Recessive traits are only expressed if they receive the recessive version (allele) from both parents. Recessive traits remain ____________ if the other gene is dominant, as with subject B.
expressed
unexpressed
Subject A
Subject B
Subject C
Genotype for Fur Color GG Gg gg
Phenotype for Fur Color
Gray Fur
White Fur

10. same different joined together
Use your vocabulary reference sheet to define the
following prefixes and suffixes.
What does homo- mean? ______________
What does hetero- mean? ______________
What does –zygous mean? ________________________
Define homozygous: _______________________________________________
Define heterozygous: _______________________________________________
Circle the following genotype(s) that are homozygous:
GG Gg gg
Circle the following genotype(s) that are heterozygous:
same
different
joined together
Homozygous means the same alleles have joined together
Heterozygous means different alleles have joined together

11. BB Green eyes bb Blue eyes Bb Green eyes
Allele
Trait
Type G
Solid gray fur
Dominant g
Striped gray fur
Recessive B
Green eyes b
Blue Eyes T
Long tail t
Short tail E
Large ears e
Small ears
Use the information above to answer the following questions and to complete the table below.
1. What is the genotype of an animal that is homozygous dominant for eye color? _____
What would this animal’s phenotype be? __________________
2. What is the genotype of an animal that is homozygous recessive for eye color? _____
3. What is the genotype of an animal that is heterozygous for eye
color? _____ BB
Green eyes bb
Blue eyes Bb
Green eyes

12. GG Solid gray fur gg Striped gray fur Gg Solid gray fur
Allele
Trait
Type G
Solid gray fur
Dominant g
Striped gray fur
Recessive B
Green eyes b
Blue Eyes T
Long tail t
Short tail E
Large ears e
Small ears
4. What is the genotype of an animal that is homozygous for solid gray fur? _____
What would this animal’s phenotype be? __________________
5. What is the genotype of an animal that is homozygous for striped gray fur? _____
6. What is the genotype of an animal that is heterozygous for fur? _____ GG
Solid gray fur gg
Striped gray fur Gg
Solid gray fur

13. tt Short tails Ee Large ears tt Short tails Tt Long tails bb Blue eyes
Allele
Trait
Type G
Solid gray fur
Dominant g
Striped gray fur
Recessive B
Green eyes b
Blue Eyes T
Long tail t
Short tail E
Large ears e
Small ears
Description
Genotype
Phenotype
Homozygous recessive for tail length
Heterozygous for ear size
Homozygous for short tails
Heterozygous for tail length
Homozygous for blue eyes
Homozygous dominant for fur
Homozygous for striped gray fur
Heterozygous for eye color
Homozygous for long tails tt
Short tails Ee
Large ears tt
Short tails Tt
Long tails bb
Blue eyes GG
Solid gray fur gg
Striped gray fur Bb
Green eyes TT
Long tails

14. Just like we can ________ the possible gamete cells of an individual, we can also predict the possible ___________ and ___________ of the offspring a set of parents might create. We do this using a tool called a _______________.
predict
genotypes
phenotypes
Punnett square
b b
G g B b
Green eyes Bb
Green eyes Bb G g
Solid Fur GG
Solid Fur Gg
Blue eyes bb
Blue eyes bb
Solid Fur Gg
Striped fur gg

15. GG (male) × Gg (female) G G G
To use a Punnett square, we start by placing the genotype of the _______ (♂) across the top of the Punnett square and placing the genotype of the ________ (♀) down the side of the Punnett square. Even though this is the conventional placement of the genotypes, mixing this up will not keep you from getting the correct answer.
male
female
G G G g
GG (male) × Gg (female)

16. You fill the boxes by writing male alleles down each ________ and filling in the female alleles across each _____.
column
row
G G G g G
G G G
g g
GG (male) × Gg (female)

17. 1 gamete gamete G G G G G G G g g
Since each gamete cell will only have ___ of these parental genes, each box represents a possible combination of genes that might be created when one of the possible male _________ cells fuses with one of the possible female ________ cells. 1
gamete
gamete
G G G g G
G G G
g g g G
GG (male) × Gg (female)

18. G G G G G G G g g percentage 25% 100%
You can discuss the outcome of a Punnett square in one of two ways. First, you can calculate the average ____________ (%) of offspring that will have a certain genotype or phenotype. Since there are 4 boxes, each box is worth _____. The Punnett square above shows that ______ of the children will have solid gray fur (G).
percentage
25%
100%

19. G G G GG GG Gg Gg genotypes phenotypes 50% 100%
Solid Fur
Solid Fur G g GG GG
Solid Fur
Solid Fur Gg Gg
It is important that you pay attention to whether the question is asking about __________or ___________.
genotypes
phenotypes
What percentage of the offspring would be expected to have a heterozygous genotype? ______
50%
What percentage of the offspring would be expected to have a solid gray fur? ______
100%

20. greatest common factor 2:2 is reduced to 1:1 using a factor of 2.
The second way is to discuss the ________ of genotypes or phenotypes. In the Punnett square, the ratio of homozygous dominant to heterozygous is ____to____ also written as ____. We always reduce our ratios using the _______________________ (GCF).
ratio 1 1
1:1
greatest common factor
G G
2:2 is reduced to 1:1 using a factor of 2. G g G
G G G
g g

21. Complete the following Punnett squares and answer the questions go with each cross. Use the tables of information on each page to answer the questions.

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