Exam #1 Flashcards
Two stages of mitosis are combined into one stage for the sake of meiosis (both I and II), which ones?
prometaphase and prophase
Plant and animal gametes share some basic features (both have eggs with low or no motility). Are these features homologous?
No
In mitosis, the chromosomes are all aligned at a plane at the “cell equator.” What stage is this?
metaphase
In mitosis, the chromosomes are in two groups and de-condensing. What stage is this?
telophase
In meiosis, the sister chromatids are still joined, and the chromosomes are moving apart in two groups to the poles of the cell. What stage is this?
anaphase I
Mendel’s work was re-discovered and became widely known in what year?
1900
A single diploid cell has divided into four haploid cells. What processes have occurred?
meiosis and cytokinesis
Describe what genotype and phenotype are and how they are different.
genotype:
- gene expression (AA, Aa)
phenotype:
- physical expression (tall, purple)
Some plants are only cultivated by human beings, but some are both cultivated and domesticated. What feature do domesticated plants have that cultivated plants lack?
domesticated plants:
- shattering process (don’t shed seeds)
- controlled population
- can’t survive on its own
cultivated plants:
- shed seed
- can survive on its own
Although now known to not be true, the idea of blending inheritance was widely believed in the 19th century.
What is blending inheritance? Give and example of how it might work.
Describe one of Mendel’s results that proved that there was no blending inheritance.
blending inheritance:
- parents make mixed offspring, offspring can never have parent’s trait
- dark * light = 100% mixed
Significance of Mendel’s dihybrid cross:
- (RRYY * rryy) produces RRYY and rryy offspring
- also proves the critical ideas of inheritance of acquired charicteristics
- the (RRYY * rryy) cross also produces offspring who have a mixture of the two
When a type A cat is crossed with another type A cat and produces six type A kittens, this suggests the genotypes of both parents are likely I^A I^A. Why is it possible that they might not both be, and what might at least one of them be?
Codominance:
I^A I^A * I^A I^B = 75% type A, 25% type AB
I^A I^A * I^A I^i = 100% type A
Prophase I is said to be the heart of meiosis. Justify this statement: What is it about prophase I that is so special? (What is something that doesn’t occur in prophase II?)
Meiosis/prophase I:
- Leptone stage
- condensing of chromosomes
- zygotene stage
- synapsis pairs homologous chromosomes
- crossing over
- tetrads (bevalents)
- pachytene stage
- crossing over
- synaptonemal complex forms between homologous chromosomes
- diplotene stage
- no cross over
- no synaptonemal complex
- homologous chromosomes held together by chiasmata
- diakinesis stage
- chiasmata slips to ends of chromatids
Consider rolling ordinary dice (6 sided). Calculate the following probabilities:
Roll two dice, get two ones:
Role two dice, get five and six in any order:
Role two dice, get five first then six second:
Role three dice, get five twice and one once, in any order:
= 1/36
= 1/18
= 1/36
= 1/72
Coat color in cats is determined by genes at several different loci. At one locus on the X chromosome, one allele (X+) codes for black fur; another allele (X^0) codes for orange fur. Females can be black (X+X+), organge (X^0X^0) or a mixture of orange and black call tortoiseshell (X+X^0). Males are wither black (X+Y) or orange (X^0Y). Bill has a female tortoiseshell cat named Patches. One night, Patches escapes from Bill’s house, spends the night out, and mates with a stray male. Patches later gives bith to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. Give the genotypes of Patches, her kittens, and the stray male.
Patches: X+X+
stray: X^0Y
orange male kitten: X^0Y
black male kitten: X+Y
tortoiseshell female kitten: X+X^0
orange female kitten: X^0 X^0
ONe of the cell cycle checkpoints is called wither the G2 or the G2/M checkpoint. It’s function is to determine whether or not the cell is ready to progress to the M phase. What specific thing is it checking for?
Confirming if the DNA is fully replicated
