Name:
Date:
Period:
Introduction to Genetics and Inheritance
I.
Homologous Chromosomes
A. What do they have in common?
1.
B. What makes them different?
1.
II.
Loci vs. Alleles
A. A ________ is the position of a gene on a chromosome.
B. An allele is a _________________________________.
1. “Two versions of the same gene.”
III.
Genotype vs. Phenotype
A. A phenotype is the observable trait of an organism based on
the _______________________________________________.
B. A ______________ is a set of alleles that determines the
expression of a particular trait.
IV.
Dominant vs. Recessive Alleles
A. Alleles usually come in two variations:
Name:
Date:
Period:
1. A _______________ allele expresses its phenotype
regardless if its paired allele is identical or different.
2. A _______________ allele expresses its phenotype only
when its paired allele is identical to it.
V.
Homozygous vs. Heterozygous
A. Homozygous refers to
_____________________________________.
B. Heterozygous refers to
_____________________________________.
C. AA = ____________________
D. Aa = _____________________
E. aa = _____________________
For each of the genotypes below, determine the phenotype:
Brown eyes (B) are dominant to blue eyes (b)
1. BB ____________________
2. Bb ____________________
3. bb ____________________
For each genotype, indicate whether it is heterozygous or homozygous:
Name:
Date:
Period:
1. AA ___________________
2. Bb ____________________
3. QQ ___________________
4. dd ____________________
How are genes passed down through gametes?
I.
Making Connections
A. Looking at the genotypes, what are the possible gametes in
references to the allele that can form?
1.
2.
3.
B. In humans, sickle cell anemia is a disease caused by a
mutation of a single locus gene which codes for an important
blood protein. The allele for the normal protein (S) is dominant
to that for the one causing sickle cell anemia. What gametes
would be produced by an individual who suffers from sickle cell
anemia?
1.
Name:
Date:
Period:
C. In areas of the very deep and damp southeastern United
States, lives what is, for all intents and purposes, a giant flying
cockroach known as a Palmetto bug. Assume that long
antennae (L) are dominant to short antennae and that normal
wings (N) are dominant to bent ones. What gametes will be
produced by an individual that is homozygous dominant for
antennae and heterozygous for wings?
1.
D. In horses, the color black is due to a dominant allele (B) and
brown color is due to the recessive allele (b).
1. What gametes would a homozygous dominant female
produce?
a)
2. What gametes would a heterozygous male produce?
a)
3. What possible zygotes would they produce if mated?
a)
Name:
Date:
Period:
I.
Monohybrid Cross - using Punnett Squares
A. Monohybrid Cross __________________________________________.
B. The Father of Genetics: ___________________
C. Father of the Punnett Square: __________________
II.
Solving Genetic Problems with Punnett Squares
1. Determine Allele Letters
2. Determine the Genotype
3. Draw Punnett Square Grid
4. Fill in possible gametes on each side
5. Run Cross (Fill in Grid)
6. ANSWER THE QUESTION!
A. In dogs, wire hair (E) is dominant to smooth (e). In a cross of a
homozygous wire-haired dog with a smooth haired dog.
a. What will be the phenotype of the F1 generation?
i.
b. What would be the genotype of the F1 generation?
i.
c. What would be the ratio of wire-haired to smooth-haired dogs in
the F2 generation?
Name:
Date:
Period:
i.
B. The ability to curl your tongue up on the sides (T, tongue rolling) is
dominant to not being able to roll your tongue. A woman, who can roll
her tongue marries a man who cannot. Their first child has his
father’s phenotype.
a. What are the genotypes of the mother, father, and child?
i.
Name:
Date:
Period:
I.
Dihybrid Crosses
A. Working with two genes
B. For a giant cockroach, assume that long antennae (A) are
dominant to short antennae and that normal wings (N) are
dominant to bent ones. What gametes will be produced by an
individual that is homozygous dominant for antenna and
heterozygous for wings? You are not doing a punnett square
just finding possible gametes.
1.
C. Review Mendel’s experiment on pea plants!
D. At the end of the experiment, what was the phenotypic ratio?
1.
Name:
Date:
Period:
I.
Incomplete & Codominance
A. Incomplete dominance is
______________________________________.
B. Codominance is
_____________________________________________.
II.
An example of incomplete dominance is
_______________________________.
III.
An example of codominance is
_______________________________________.
A. A woman with blood type A is trying to figure which of three
men she slept with is the father of her child with a blood type O.
Which of the following is not the father?
1. JimBob (AO)
2. Paquito (OO)
3. J’waun (AA)