Mitosis/Meiosis Flashcards Preview

Genetics > Mitosis/Meiosis > Flashcards

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
- Non-disjunction
- Endoreduplication (endomitosis)


Which types of atypical mitosis cause abnormal chromosome #'s?

- multipolar division
- non-disjunction
--> 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?

- Microscopy:
- 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


What causes aneuploidy?

Meiotic non-disjunctions
(most frequent in oogenesis)
-sex chromosome non-disj. more common in spermatogenesis