Mitosis/Meiosis Flashcards Preview

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Flashcards in Mitosis/Meiosis Deck (12):
1

What is chromosome segregation?

Process of distributing a copy of each chromosome to each daughter cell (during mitosis)

2

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

3

What are types of atypical mitosis?

- Multipolar division
- Bridge formation
- No cytokinesis
- Non-disjunction
- Endoreduplication (endomitosis)

4

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

- multipolar division
- non-disjunction
--> polyploid can occur from endomitosis

5

What is a H3P?

Phosphorylated H3 histone, needed for chromosome condensation

6

What is PCNA?

=Proliferating cell nuclear antigen
- cofactor for DNA polymerase, expressed in S phase

7

What is Ki67 antigen?

Associated with cell proliferation
- thus NOT expressed in G0

8

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

9

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)

10

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

11

What are pseudoautosomal regions?

Pseudoautosomal regions (PAR) 1 and 2 are on the X and Y chromosomes. They pair and recombine during meiosis

12

What causes aneuploidy?

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