Mitosis
What is a centromere?
The region that chromatids stay attached to one another by a protein called what? - 2 possible proteins
What is the process of meiosis used to produce?
Gametes! Egg (Oocyte) and Sperm
Chromosomes are composed of _____ which is composed of _____ and ______.
Chromosomes are composed of CHROMATIN which is composed of DNA and PROTEIN (histone).
What is the difference between Haploid and Diploid?
Haploid(n) - 1 set of chromosomes (gametes)
Diploid (2n) - 2 complete sets of chromosomes (an organism)
What is a genotype vs a phenotype?
Genotype : the combination of alleles that they possess for a specific gene.
Phenotype: the combination of their observable characteristics or traits
Put the following steps in order:
Metaphase, Telophase, Prometaphase, Anaphase, Prophase, Cytokinesis
Prophase, Prometaphase, Metaphase, Anaphase, Telophase, Cytokinesis
PPMAT + Cytokinesis
How are tetrads made during meiosis? And at what stage?
During Prophase I, homologous chromosomes (dyad sister chromatids - 1 pair from each parent) find each other and become closely associated.
Maternal Dyad + Paternal Dyad = Tetrad
Explain the difference between sister chromatids and homologous chromosomes?
Sister chromatids - identical pair
Homologous chromosomes - 1 from mom and 1 from dad
What is the function happening at :
G1
S
G2
G1- Primary Growth Phase
S - Synthesis - replication of DNA -> Monad to Dyad
G2- Organelles Replicate, Microtubules organize, essentially preparing for cell division.
1:2:1 and 3:1.
Which ratio represents the genotypic ratio and the phenotypic ratio?
Pheotypic - 3:1
At what point during Mitosis do the cells divide and the cohesion proteins are removed from all chromosomes?
Anaphase!
What type of microtubles pull the cells apart?
Explain Crossing Over and name the site of this process.
The recombination between NON-sister chromatids. (mom and dad chromatids swap information)
This produces unique combinations of genetic info.
Site = Chiasmata
Chromatin Packaging:
Place the following in order from least coiled to most:
Solenoid, Rosettes, DNA double helix, Chromosome, Chromatin Loop, Nucleosome.
DNA double helix, Nucleosome, Solenoid, Chromatin Loop, Rosettes, Chromosome
At what point to histone proteins come in?
What is independent assortment?
Does crossing over occur in this process?
The important process of producing genetically variable offspring. This is the shuffling of maternal and parental traits into different gametes.
NO! This is INDEPENDENT of crossing over!
Define these pairings:
YY, Yy, yy
YY - homozygous dominant
Yy - heterozygous
yy - homozygous recessive
Where do the microtubles attach to the chromatid to separate a pair?
Kinetochore!
At what region is the kinetochore located?
During evolution, what had to change mitosis to support meiosis?
-Pairing of homologous chromosomes
- Crossover (Prophase I)
- Sister chromatids stay together in Anaphase I
- Suppression of DNA replication during interphase between Meiosis I and II.
Describe the difference between eukaryotic and prokaryotic chromosomes.
Prokaryotic chromsomes are circular, Eukaryotic chromosomes are linear.
What is the difference between a centrosome vs a centromere?
Centrosome - organize and direct microtubule growth
Centromere - The region that chromatids stay attached to one another by a protein called cohesion or ____.
What is the purpose of a testcross?
What do you always cross a unknown with?
It is used to determine the GENOTYPE of an individual with a dominant PHENOTYPE.
You ALWAYS cross with a homozygous recessive in the case of a testcross.
Related to cancer:
What type of genes slow the cell cycle?
What type of genes accelerate the cell cycle?
- When DNA is damaged, cell division is halted and repair enzymes are stimulated. If beyond repair, p53 protein will direct the cell to go through apoptosis.
Accelerate - Proto-oncogenes (ex: Cdk)
- When mutated these cause cancer
What are two different types of meiotic errors that can occur during meiosis?
Nondisjunction - the failure of chromosomes to move to opposite poles during divison
Aneuploid Gametes - gametes with missing or extra chromosomes.
During Anaphase I in meiosis and Anaphase in mitosis, name the difference.
In Anaphase I, homologous chromosomes separate.
In Anaphase, sister chromatids separate.
Does synapsis AND crossing over occur in Meiosis or Mitosis?
EXPLAIN why it can happen in one and not the other.
Meiosis!
Mitosis is essentially the duplication of a cell. Meiosis is the creation of unique gametes. You are having cross over at Chiasmata (crossing over site) between two non-sister chromatids, aka mom and dad chromatids.
Synapsis is when tetrads are produced and we know that tetrads are not possible in mitosis!
The difference between the rule of addition and the rule of multiplication.
^^^ I remember being asked this on my exam!
Rule of Addition:
Probability of 2 mutually exclusive events occurring simultaneously is the sum of their individual probabilities.
EX: When crossing Pp x Pp what is the probability of having a Pp offspring?
0.25 + 0.25 = 0.5
( Pp + pP )
Rule of Multiplication:
Probability of 2 independent events occurring simultaneously is the product of their individual probabilities.
EX: When crossing Pp x Pp what is the probability of having a pp offspring? 0.5 x 0.5 = 0.25