Mitosis and Meiosis, Chromosomes and Karyotypes Flashcards
Homolog
Chromosome similar in size and sequence
Somatic cells vs. germ
Diploid vs haploid
46 vs 23
What accounts for normal genome variation
SNP - most common
Indels
Microsatellites
CNV
Gene duplication possiblities
Degradation —- loss
Neofunctionalization - New function
Subfunctionalization - different function
Arms of chromosome
P - short
Q - long
Area betwen P and q arm
Centromere
Composition of chromosome
DNA and protein
How to do a karyotype?
Giesma stained
Arrange by size with homologs next to each other
Large scale can be visualized
Philidelphia chromosome disease and numbers
9 and 22
Chronic myelogenous leukemia (also ALL and AML)
Phildelphia chromosome mutation that occurs
Translocation
ABL moves from 9 to 22
BCR and ABL now next to each other on 22
Tx for CML
Gleevac - ABL inhibitor
ABL function
Cell proliferation
ABL name and structure
Abelson murine leukemia virus homolong 1 (tyrosine kinase)
BCR
Breakpoint cluster region
Mechanism of ABL/BCR mutation
Promotor from BCR will drive constant expression of ABL
Burkitt’s lymphoma mutation
IGH-MYC fusion
Increased MYC activity
Only exons 2 and 3 from MYC make it
MYC and IGH chromosomes
8 and 14
IGH function
Expressed all the time in B-cells
Increased MYC due to
Many things
Sometimes a IGH-MYC translocation
Mitosis
Generate 2 daughter cells with same genetic makeup
Cells in G phase
2n=diploid
Cells after S phase
4n = tetraploid
G1 phase
Gap before deuplciatiopn
S
DNA synthesis and chromosome duplication
G2
Interphase gap before mitosis
Mitosis location
Somatic cells of the body
Shortest part of cell cycle
M
Sister chromatids
ID copies of chromosomes held together at centromere
Centrosomes
Cellular organelles involved in moving chromosomes apart
Metaphase
Duplicated chromosomes randomly line up at metaphase plate
Microtubules attach
Centrosomes to centromeres
Cyclins and CDKs
Promote cell cycle progession
CDKIs
Involved in cell cycle arrest
Cell cycle checkpoitns and questions
G1-S - Is DNA intact?
S - is replication complete?
G2-M - are chromosomes aligned?
pRb in normal body
Unphosphorylated Rb binds to E2F and DP…pRb phosphorylated and E2F/DP dissociates and activates cyclins, CDKs and others
In Retinoblastoma
Rb is mutated and does not form…cannot bind to E2F/DP in order to turn off the cell cycle
Meiosis
Terminal event
Chromosomal reduction from diploid to haploid
Meiosis synopsis
Chromosomes replicate
Homologs line up and then separate during meiosis 1
Sister chromatids separate during meiosis 2
Errors in segregation of meiosis result in
Aneuploidies
Spermatogenesiss
Spermatogonial stem cell ——- spermatogonium —— after puberty, primary spermocyte…replicates…after meiosis 1, secondary spermocyte…after meiosis 2, spermatozoa
Oogenesis
Oogonium stem cell mitosis to pirmary oocyte (chromosomes replicate and arrest in prophase 1)…during puberty, meiosis 1 completes in 1-2 oocytes/month (secondary oocyte arrest in metaphase 2)(polar body produced)`…fertilization…meiosis 2 completes (produces polar body)…pronuclei fuse and zygote formed
Synaptonemal complex
Keeps homologs lined up perfectly together when lined up
Frequency of crossing over is related to
Greater distance…greater probability of crossover
Crossing over results in what gametess?
Two parental and two recombinante
Similarities of mitosis and meiosis
One round of DNA synthesis Sister chrom Nucleus disappears Chromosomes line up Centromeres attach Daughter cells
Differences
Diploid vs haploid
Mutations in mitosis affect individual…mutations of meisosi affect offsrping
One cell division in mitosis vs 2 in meiosis
Homologs random in mitosis, synapse and cross over in meiosis
