Meiosis and mitosis summerary

Question 1

Name the two divisions of meiosis

Answer 1

meiosis I and meiosis II

Question 2

Define meiosis

Answer 2

nuclear division which leads to generation of haploid cells

Question 3

What is a bivalent?

Answer 3

structure formed by two closely aligned duplicated homlogos

Question 4

What are the 5 stages of prophase I ?

Answer 4

Leptotene
Zygotene
Pachytene
Diplotene 
Diakinesis

Question 5

What happens during Leptotene?

Answer 5

homologous chromosomes condense (however, not fully), pair and genetic recombination begins

Question 6

What happens during Zygotene?

Answer 6

SC (Synaptonemal complex) starts to assemble; synapsis and recombination are taking place

Question 7

What happens during Pachytene ?

Answer 7

SC is complete, recombination finishes, homologues are very tightly linked

Question 8

What happens Diplotene?

Answer 8

– disassembly of SC, condensation and shortening of chromosomes After this chiasmata are visible. Homologues can segregate.

Question 9

Describe the Synaptonemal Complex shape

Answer 9

Each homolog is organized around a protein axial core, and synaptonemal complex forms when these homolog axes are linked by rodshaped transverse filaments. The axial core of each homolog also interacts with the cohesin complexes that hold the sister chromatids together

Question 10

When does SC assembly begin?

Where does disassembly work?

Answer 10

Assembly begins in early zygotene and completed in pachytene

Disassembled in diplotene

Question 11

How does meiosis differ from mitosis?

Answer 11

Meiosis I differs from mitosis in 3 major ways: (1) glued together sister kinetochores remain attached to the same spindle pole, (2) chiasmata keep homologs together which allows bi-orientation, (3) centromeric cohesin on sister chromatids remains bound through anaphase I.