Cell Division and Genetics HW
1. Name 4 differences between mitosis and meiosis.
2. Sketch a mitotic cell with 6 chromosomes as it might appear at
anaphase.
3. Show a cell with the same number of chromosomes as above at
prophase 1and anaphase Iof meiosis.
4. Show the same cell as above at anaphase II of meiosis.
5. Humans have
chromosomes or 23 pairs of
cells.
-----chromosomes and are
6 Human gametes have
chromosomes and are
cells.
7. A diploid cell in the ovary has 12 chromosomes
a. How many tetrads (chromosome pairs) are present during:
1. Prophase I
2. Prophase II
b. How many chromatids are present during: ·
1.Metaphase Iof meiosis
2. Metaphase II of meiosis
8. Use the following key to answer the following questions. Each answer
may be used once, more than once,or not at all.
a. this statement is true for mitosis only.
b. this statement is true for meiosis I
only.
c. this statement is true for meiosis II only.
d. this statement is true for mitosis and meiosis I.
e. this statement is true for mitosis and meiosis II.
1. A cell divides to produce two daughter cells that are genetically
identical.
2. Homologous chromosomes undergo synapsis (pairing) and crossing
over occurs
3. Centromeres uncouple and chromatids are separated from each other.
4. Independent assortment of chromosomes occurs.
5. This process is preceded by replication of the DNA.
Genetic Concepts Worksheet
Key terms:
Gene: A segment of DNA that is used as the template by polymerase to encode the
mRNA that will eventually be translated to a specific peptide
Allele: One of many different forms that a particular gene can have (ex. The genes
encoding eye color can exist as many different alleles)
Homozygote : An individual who has the same allele on each of his or her parental
chromosomes.
Some genetic terms
Heterozygote: An individual who has a different allele on each of his or her
parental chromosomes.
Genotype: The alleles that exist at the locus of a gene.
Phenotype: The trait that is expressed due to the alleles that are found at a specific
locus or loci.
Dominant: A term used to compare one allele to another. The dominant allele will
be the same trait that is expressed in a heterozygote compared to that of a
homozygou s individual with two copies of that particular allele.
Recessive: A term used to compare one allele to another. The recessive allele will
not be expressed in a heterozygous individual. Furthermore, the only way for a
recessive allele to be expressed is for an individ ual to have two copies of the
recessive allele.
Complete Dominance: In the event of a heterozygote, the only trait that is
·expressed in the phenotype is that of the dominant allele.
Incomplete Dominance: In the event of a heterozygote, the trait expressed is
somewhere between the two homozygous phenotypes
.
Co-Dominance: Refers to an instance of multiple alleles that can occur at a specific
locus, where one dominant allele and another dominant allele occur, and the traits
for both are expressed in the phenotype.
Monohybrid Cross: A scenario that p red icts the ratios of genotypes and
phenotypes that would be produced by the mating of two individu als that are
heterozygous for a single trait of interest.
Dihybrid Cross: A scenario that predicts the ratios of genotypes and phenotypes
that would be produced by the mating of two individ uals that are heterozygous for a
two traits of interest.
Exercise 1: Monohybrid Cross; Complete Dominance
Mary has Brown Eyes (Bb) and Greg has Brown Eyes (Bb). Use the Punnett square
below to determine the likelihood (percent chance) that they would have a child
with the listed genotypes or phenotypes:
a) Child with Brown Eyes:
b) Child with Blue Eyes:
c) Child that is Homozygous for the Dominant Allele:
d) Child that is Homozygous for the Recessive Allele:
e) Child that is Heterozygous:
Exercise 2: Monohybrid Cross; Incomplete Dominance
Nancy has Green Eyes (Bb) and Mitch has Green Eyes (Bb). Use the Punnett square
below to determine the likelihood (percent chance) that they would have a child
with the listed genotypes or phenotypes if BB = Brown Eyes and bb = Blue Eyes:
a) Child with Brown Eyes:
b) Child with Green Eyes:
c) Child with Blue Eyes:
d) Child that is Homozygous for the Dominant Allele :
e) Child that is Homozygous for the Recessive Allele:
t) Child that is Heterozygous :
Exercise 3: Di-Hybrid Cross: Complete Dominance
Julie has a male cat that has black fur (Bb) and long haired (Ll). Aaron has a
female cat that has black fur (Bb) and is long haired (Ll). Use the Punnett square
below to determine the different combinations of genotypes that would arise from a
mating between these two cats if the genes that encode fur color and hair length are
not linked.
Genotypes & Phenotypes
BB = black fur
LL = long haired
Bb = black fur
Ll = long haired
bb = brown fur
ll = short haired
Cross: Bbl/ x Bbl/
a) What is the percent chance that a kitten born from the mating will have black fur
that is long?
b) What is the percent chance that a kitten born from the mating will have brown
fur that is long?
c) What is the percent chance that a kitten born from the mating will have black fur
that is short?
d) What is the percent chance that a kitten born from the mating will have brown
fur that is short?