3/ sexual cell cycle

Question 1

nuclear cell cycle in saccharomyces cerevisiae

Answer 1

• haploid through most of its life cycle
• 2 mating types: a and alpha
• on e a and alpha combine to give transient diploid stage
• giving 4 haploid products

Question 2

what is a dyad

Answer 2

• each replicated chromosome, 2 sister chromatids with a single centromere

Question 3

what is a bivalent

Answer 3

• 2 dyads joined together

Question 4

NEW INFO: prophase of meiosis 1

Answer 4

• leptotene: replicated chromosomes start to contract
• zygotene: chromosomes line up in homologous pairs (synapsis). held together by synaptonemal protein complex
• pachytene: crossing over between non sister chromatids
• diplotene: chromosomes separate a bit but chiasma still visible
• diakinesis: chromosomes contract even further

Question 5

what does homologous recombination - crossing over- rely on

Answer 5

• large sections of homology for homologous chromosomes to align in the 1st place