Mitosis
My cell is diploid 2n = 6; what ploidy is my cell after cytokinesis?
My cell is diploid 2n = 36; before replication, what stage am I in?
Interphase - Gap 1
True or False: Point mutations are only deleterious in coding regions
False
A pea plant with genotype AaBb is crossed with another pea plant with genotype AaBb. Assume complete dominance. What percentage of the offspring will be completely recessive?
1/16
If I am a diploid with 46 sister chromatids, how many molecules of DNA do I have after DNA replication?
46 DNA molecules
The Law of Independent Assortment and the Law of Segregation
Metaphase I; Anaphase I
What mutation changes only a single nucleotide within the reading frame?
Point mutation (substitution/indel)
A genetic disorder is caused by an autosomal recessive allele (a). Two unaffected parents have a child with the disorder.
What are the most likely genotypes of both parents, and what is the probability that their next child will also have the disorder?
P1 and P2 must be Aa because the disorder is autosomal recessive.
Every child has 1/4 chance of inheriting the disease phenotype.
This happens when segments of genetic material are swapped between two different (non-homologous) chromosomes.
Reciprocal translocation
This process only occurs during Prophase I of meiosis, where non-sister chromatids of homologous chromosomes exchange genetic segments to increase genetic diversity.
Crossing over
True or False: A deleterious mutation in bacteria will be directly inherited by 50% of the daughter cells
False
A woman is heterozygous for an X-linked recessive disorder, and the father does not have the disorder.
What is the probability that a daughter will inherit the disorder? Then what is the probability a son will?
Daughter - 0% (note 50% will be carriers)
all daughters receive the unaffected Xᴬ from their father
Son - 50%
Dad gives them Y and mom gives them Xᴬ or Xᵃ
An organism has a haploid chromosome number of n=5. A cell undergoes DNA replication followed by mitosis. At the end of mitosis and cytokinesis, how many chromosomes and chromatids will each daughter cell contain?
5 chromosomes, 5 chromatids
In a human cell 2n=46, if a single nondisjunction event occurs for a pair of sister chromatids during Meiosis II, what will be the resulting chromosome counts in the four gametes produced?
Two gametes will be normal (23 chromosomes), one will have an extra chromosome (24 chromosomes), and one will be missing a chromosome (22 chromosomes)
A diploid organism has two genes. The first gene codes for red pigment (A_) or white pigment (aa). Another gene codes for a functional enzyme. The normal allele (B) produces a functional protein causing pigment, while a mutated allele (b) contains a loss-of-function mutation.
The mutation is recessive, meaning an individual must inherit two copies of the mutated allele to express the disorder.
If two heterozygotes reproduce, what is the probability their offspring will express red pigment?
(3/4) * (3/4) = 9/16
3/4 chance that offspring will have AA or A_
3/4 chance that offspring will have BB or B_ (at least one functional protein needed for pigment)
A genetic disorder is caused by an autosomal dominant allele (A). The normal allele is a. Individuals with either genotype AA or Aa express the disorder, while individuals with genotype aa are unaffected.
A heterozygous affected parent reproduces with an unaffected parent.
What is the probability that the first three children will be affected and the last two unaffected?
(1/2 * 1/2 * 1/2 * 1/2 * 1/2) = 1/32
All have an equal 50% chance of being affected or unaffected. Since these are independent events (not mutually exclusive), we use the and rule.