Lecture 9 - Meiosis Flashcards
What is achieved in Meiosis I?
division of the parent nucleus into 2 daughter nuclei & cytokinesis or interkinesis
What is achieved in Meiosis II?
4 daughter cells are produced, haploid cells
Prophase I
- chromosomes condense
- homologous chromosomes pair up & enter “synapsis”
- synaptomeal complex forms
- crossing over occurs between non-sister chromatids
- tetrads become visible; cross-over points appear ah chiasmata
- nuclear membrane dissolves, spindle fibres being forming
synapsis
refers to the physical pairing of homologous chromosomes
synaptomeal complex
protein structure that forms between the homologous chromosomes during synapsis
chiasmata
chiasmata refer to the physical points at which crossing-over
Metaphase I
- tetrads line up on equator
- each chromosome of a homologous pair attaches to spindle fibres from opposite ends of the pole
Anaphase I
- chiasmata dissolve; homologous chromosomes move to opposite poles
Telophase I
- nuclear envelope reforms
- resulting cells have 1/2 # of chromosomes, each consisting of 2 sister chromatids
Interkanesis/Cytokinesis
- daughter nuclei become enclosed into separate daughter cells
Prophase II
chromosomes condense
Metaphase II
chromosomes align @ equator
Anaphase II
centromeres divide & sister chromatids move to opposite poles
Telophase II
chromosomes uncoil, nuclear envelope & nucleoli begin to reform
Cytokinesis (TII)
division of cytoplasm, resulting in 4 daughter cells
