Lecture 1

Question 1

Define:

Homologous Chromosomes/ Homologs

Answer 1

a pair of similar but non-identical chromosomes
- one is paternal in origin and the other is maternal
- have the same gene order but potentially different alleles

Question 2

Draw the Human Life cycle

add the n values at the stages

Answer 2

check notes :D

Question 3

Define

What is C-value?

and draw the values changing in a sperm cycle

Answer 3

amount of DNA measured in based pairs
- because we have lots of FNA does not mean we are more complex

Question 4

Define:

What is n- value?

define haploid, diploid, draw mitotic cell through cell cycle

Answer 4

• number of chromosomes found in the haploid cell
• haploid: the single set of unpaired chromosomes
• equal to the number of chromosomes in the gametes
• diploid: consisting of a homologous pair for every chromosome; considered 2n ex. 2n = 46
• doesn’t change in a mitotic cell, only reduces in meiosis

Question 5

What is the purpose of Mitiosis?

Answer 5

• creation of genetically identical daughter cells
• separation of chromatids
  1. replicate chromosomes into chromatids in S phase
  2. separate chromatids in M (mitotic) phase

Question 6

What is the purpose of Meiosis

Answer 6

• generate haploid gamete
• generate genetic diversity
  1. seperate homologs (Meiosis 1)
  2. separate sister chromatids (Meiosis 2)
• all daughter cells are gentically different

Question 7

Describe Meiosis

just the overview, draw it

Answer 7

• 2 phases: 1; reductional division, 2; equational division

check notes

Question 8

Meiosis 1

What happens in Prophase 1

define: synapse, bivalent

Answer 8

• Chromosomes condense
• crossing over occurs: phsyical exchange od DNA b/w non-sister chromatids of homologs
• synapse: pair up along localized points
• Bivalent: synapsed homologs

Question 9

Meiosis 1

What happens in Metaphase 1

Answer 9

• biavlents line up at metaphase plate
• crossing over is complete
• independent assortment occurs

Question 10

meiosis 1

what happens in anaphase 1

Answer 10

• disjunction of homologs
• one pair of sister chromatids moves towards each cell pole
• sister chromatids stay attached together

Question 11

Meiosis 1

what happens in telophase 1?

Answer 11

• cytokinesis
• in some organisms, Meiosis 1 moves directly into meiosis 2 and telophase is almost non-existent

Question 12

What happens in Meiosis 2?

Answer 12

• like mitosis that it is an equational division
• resilts in 4, non identical haploid products
• males all four turn into sperm; females have 1 large eggs and 2 polar bodies
• haploid cells