Cell Cycle
List the order of the the steps of the cell cycle and which step lasts the longest?
G1, S, G2, Mitosis or Meiosis
Interphase (G1, S, G2) is the longest (G1 specifically)
List all the steps of Mitosis AND what is the result of one cell entering mitosis
Prophase, Prometaphase, Metaphase, Anaphase, Telephase
2 identical diploid somatic cells
Describe the result from one cell entering meiosis
4 genetically unique haploid gametes
Genotype for affected individuals for an autosomal dominant trait
Homozygous dominant (AA) or Heterozygous (Aa)
Which Mendel's law do linked genes break? What restores the law?
Law of Independent Assortment - two or more traits randomly divide and recombine independently of each other.
Crossing over breaks apart linked genes and restores the law of independent assortment.
What is created during the S phase? What is the structure called?
DNA replication - sister chromatids
What happens during prophase?
Chromosomes condense, spindle fibers form, centrioles move to opposite poles, and nuclear envelope breaks down.
Important actions in Prophase I
Crossing over - (chiasmata forms) exchange of genetic information
Genotype for affected individuals for an autosomal recessive trait
Homozygous recessive (aa)
A white flower and a black flower mate to create a grey flower. What is this called? What are the genotypes?
Incomplete dominance
White = A
Black = a
Grey = Aa
G1/S Checkpoint - what two things are being checked?
DNA and Growth Factors
What happens during prometaphase?
Spindle fibers attach to kinetechore of each sister chromatid
What are the three things that create genetic diversity and when do they happen?
Crossing over - Prophase I
Independent Assortment - Metaphase I
Random Fertilization - Fertilization
Give the phenotypic ratio of the offspring when looking at two traits and both parents are heterozygous for each trait (complete dominance)
9:3:3:1
Give an example of a tumor suppressor gene, what checkpoint does it work in, and how many copies must be mutated to cause cancer?
p53
G1/S checkpoint
2 copies must be mutated to the "on" position.
What happens during G2?
Prep for division, centrioles replicate
What happens during anaphase?
Sister chromatids divide.
Anaphase I - separation of homologous pairs, chromosome number decreases from 2n --> n (reductive division)
Anaphase II - separation of sister chromatids, chromosome number stays the same, from n --> n (mitotic division)
If a mother is affected for an X-linked recessive trait, what percentage of sons will be affected?
100%
What do proto-oncogenes normally do? And how many copies must be mutated to cause cancer?
Code for growth factors
One mutated copy is turned permanently on and causes cancer.
G1/S - DNA and Growth Factors
G2/M - DNA
Late Metaphase - Makes sure spindles are attached to every chromatid
If a cell starting mitosis has 30 chromosomes, how many chromosomes will it have at the end of mitosis?
30 chromosomes
State Mendel's Law of Segregation and explain when each part happens during meiosis
For each trait (gene) there are two alleles (diploid, homologous pairs) that randomly divide (anaphase I) and recombine (fertilization).
Which traits skip generations and why?
Autosomal recessive and X-linked recessive
Because two unaffected parents can have affected children if both are heterozygous (autosomal) or mother is heterozygous (X-linked).
Describe the differences between pleiotropy, epistasis, polygenic, and aneuploidy.
Pleiotropy - One gene affects multiple phenotypes. Ex. cystic fibrosis and sickle cell anemia both trace back to the same gene
Epistasis - One gene can affect/obscure the effects of another gene. Ex. Albinism
Polygenic - More than one gene affecting a single trait. Ex. Height, eye color
Aneuploidy - incorrect number of chromosomes. One less = monosomy, one more = trisomy.