Cell cycle - Meiosis Flashcards
What is the main purpose of meiosis?
To produce gametes and generate genetic diversity
Where does meiosis typically occur?
In reproductive organs
What are the two main stages of meiosis?
Meiosis I and Meiosis II
Is there DNA replication between meiosis I and II?
No
What does ploidy number represent?
The number of chromosome sets in a cell
What happens to ploidy during meiosis?
It is halved (e.g. 46 → 23 in humans)
What is a chiasma?
The point where crossover happens between chromosomes
What is a bivalent?
A pair of homologous chromosomes joined together during meiosis I
Name the 5 stages of Prophase I.
Leptotene Zygotene Pachytene Diplotene Diakinesis
What occurs in leptotene?
Chromosomes condense
What occurs in zygotene?
Homologous chromosomes pair up and synaptonemal complex begins to form
What occurs in pachytene?
Chromosomes fully pair and crossover occurs
What occurs in diplotene?
Synaptonemal complex dissolves chiasmata remain
What occurs in diakinesis?
Bivalents attach to spindle and align at equator
What facilitates crossover?
The synaptonemal complex
What is the role of crossover?
Mixes genetic material from both parents and increases diversity
When do homologous chromosomes separate?
Anaphase I
Do sister chromatids separate in meiosis I?
No
Do sister chromatids separate in meiosis II?
Yes
What lines up at the equator during metaphase I?
Homologous pairs (bivalents)
How many kinetochores attach per chromosome in metaphase I?
One
What happens during telophase I?
Nuclear membranes reform and chromosomes decondense
What follows telophase I?
Cytokinesis and a variable interphase (no DNA replication)
What is the difference in genetic identity between mitosis and meiosis?
Mitosis makes identical cells meiosis makes genetically different cells
