Flashcards in Mitosis/Meiosis Deck (12):
What is chromosome segregation?
Process of distributing a copy of each chromosome to each daughter cell (during mitosis)
What is a centrosome? What does it do?
Aka microtubule organizing center (MTOC)
- form foci with microtubules radiating out during PROPHASE of mitosis
- gradually move to poles of cell
What are types of atypical mitosis?
- Multipolar division
- Bridge formation
- No cytokinesis
- Endoreduplication (endomitosis)
Which types of atypical mitosis cause abnormal chromosome #'s?
- multipolar division
--> polyploid can occur from endomitosis
What is a H3P?
Phosphorylated H3 histone, needed for chromosome condensation
What is PCNA?
=Proliferating cell nuclear antigen
- cofactor for DNA polymerase, expressed in S phase
What is Ki67 antigen?
Associated with cell proliferation
- thus NOT expressed in G0
What are methods to study the cell cycle?
- division markers (PCNA, H3P, Ki67 antigen)
- detecting S phase
- Fucci (fluoresc. ubiqtnd cell cycle indicator)
- mitotic index (MI)
(MI= mitotic cells/total cells x 100)
- Flow cytometry
What are homologous chromosomes?
They are chromosomes that contain DNA that code for the same gene
- BUT, homologous chromosomes are NOT replicas of each other (sister chromatids are exact replicas)
List steps in Prophase I, and significance for each one.
1) Leptotene: chromosome condenses
2) Zygotene: synapsis begins, synaptonemal complex begins to form, holds chromosomes together (essential for recombination)
3) Pachytene: synapsis complete, forms bivalent (tetrad)
- CROSSING over occurs!!!
4) Diplotene: synaptonemal complex starts to break down, bivalents start to separate, held together by chiasmata
5) Diakinesis: chromosomes reach max. condensation
What are pseudoautosomal regions?
Pseudoautosomal regions (PAR) 1 and 2 are on the X and Y chromosomes. They pair and recombine during meiosis