Cell Division I
Does DNA replication occur before or after mitosis? And in what phase does the replication occur?
Before! It occurs in the S phase.
No.
Define evolution.
A change in allele frequency over time.
How does the assumptions of Hardy-Weinberg Equilibrium relate to the processes of evolution?
They are opposites.
Describe the bottleneck effect.
A sharp reduction in the size of a population due to environmental events, which results in a significant loss of genetic variation.
Which process reduces chromosomes number from 2n to n?
Meiosis
Gwen was playing soccer, and she abruptly fell and scraped her skin on the hot grass. What cell division will occur to replicate new skin cells?
What is genetic drift?
A random change in allele frequency
What are the assumptions of Hardy Weinberg Equilibrium?
1. Large population size
2. Random Mating
3. No mutations
4. No gene flow/migration
5. No natural selection
Describe the difference between an allele vs a gene.
The main difference is that a gene is a specific segment of DNA that determines a particular trait (like eye color), while an allele is a specific version or variant of that gene (like blue vs. brown eye color).
What is the purpose of mitosis?
- To produce two identical somatic daughter cells
- Tissue repair
- Growth and development
What are differences between meiosis and mitosis?
- Meiosis produces four genetically unique daughter cells
- Meiosis undergoes crossing over and independent assortment
- Meiosis undergoes two rounds of cell division
What are the five processes (fingers) of evolution?
1. Small population (pinky)
2. Non random mating (ring finger)
3. Mutations (middle finger)
4. Gene flow/ migration (pointer finger)
5. Natural selection (thumb)
Explain the variables of Hardy Weinberg Equilibrium represent. (p2,2pq,q2). What are the equations?
p2 --> frequency of homozygous dominant genotype (AA)
2pq --> frequency of heterozygous genotype (Aa)
q2 --> frequency of homozygous recessive genotype (aa)
p2+2pq+q2=1
p+q=1
Describe each of the terms:
Chromosome
Chromatid
Centromere
Chromosome: The entire structure of condensed DNA (either single or paired)
Chromatid: One half of a replicated chromosome
Centromere: Constricted region of a chromosome that holds sister chromatids together
List the entire cell cycle:
G0 phase
Interphase (G1, S, G2)
M phase (PMAT and Cytokinesis)
Describe independent assortment, what phase does it occur in, and why is it important?
- Occurs in Metaphase I
- Different genes are inherited independently of one another
- Creates genetic diversity in offspring by ensuring that the inheritance of one trait does not affect the inheritance of another
A group of early giraffes lives in a lush forest with many trees and shrubs of different heights to feed on. These giraffes have necks of various lengths, with most giraffes having a medium length neck. Then a blight passed through the area, killing off all of the low growing plants, leaving only tall trees whose leaves are far off the ground. Giraffes with shorter necks now have a hard time getting food, while those with longer necks can feed on the high-growing leaves. After several generations, the giraffes in this area all have longer necks than those before the blight. What type of selection has occurred in this giraffe population?
These giraffes have experienced directional selection.
A group of scientists is studying a certain species of mouse. Previous genetic analysis has shown that fur color in this species is controlled by a single gene that has two alleles: a dominant allele F that is associated with dark fur, and a recessive allele f that is associated with light fur.
The scientists collected data about a population of these mice to help determine the population’s fur color allele frequencies. They found that out of 952 mice in the population, 238 mice had light fur.
Assuming that the population is in Hardy-Weinberg equilibrium, which of the following is the number of mice in the population that have the genotype Ff?
476 mice
A population of frogs has 37 individuals who are brown in color and 194 individuals who express the dominant green color. What is the dominant allele frequency for this population?
0.6
Identical twins develop from the same fertilized egg. However, one twin has a chromosomal abnormality while the other is normal. What most likely happened?
Early mitosis issue
A developing embryo was tested and was found to have developmental issues due to abnormal cell growth during its development. Genetic analysis reveals that the embryo has an abnormal number of chromosomes. Did the mistake occur in mitosis or meiosis, and what phase did it occur in?
Mitosis, Anaphase
Give and explain five evidences of evolution.
- Convergent evolution (Two species from different lineages independently evolved similar traits)
- Homologies (Similarities that occur due to decent from a common ancestor)
- Vestigial structures (Similarities that occur due to decent from a common ancestor)
- Selective breeding ( Sexual or Artificial)
- Founder effect (Small group establishes new,
isolated population)
- Bottleneck effect (Population is drastically reduced, Increased risk of inbreeding, Endangered species)
- Fossil Record
- Endemic species
The ability to taste PTC is due to a single dominate allele "T". You sampled 215 individuals in biology, and determined that 150 could detect the bitter taste of PTC and 65 could not. Calculate all of the potential frequencies.
p= 0.45
q= 0.55
p2= 0.2025
2pq= 0.495
q2= 0.302
There is a population of 120 insects with long(dominant) and short wings (recessive). When observing the population you see 31 insects with short wings. Calculate all potential frequencies.
p= 0.492
q= 0.508
p2=0.242
2pq=0.500
q2=0.258