Meiosis

Question 1

Meiosis

Answer 1

the process that produces haploid gametes from diploid cells in the ovaries and testes

Question 2

The two key outcomes of meiosis: (2)

Answer 2

1. Reduction division
   - produces daughter cells with fewer chromosomes
2. Recombination
   - the products of meiosis have different combinations of genes

Question 3

Interphase (3)

Answer 3

• like somatic cells, gametes also go through the growth and synthesis phase of interphase before dividing
• chromosomes are replicated during the S phrase of interphase
• at the start of meiosis, a gamete cell contains duplicated chromosomes

Question 4

Prophase 1 (5)

Answer 4

• each pair of homologous chromosomes align side by side
• synapsis takes place
• chromatin condenses to form chromosomes
• spindle fibers form
• nuclear membrane dissolves

Question 5

Synapsis

Answer 5

• crossing over swaps genetic info and increases diversity

Question 6

Metaphase 1 (2)

Answer 6

• Chromosomes line up as homologous pairs

- the orientation of each pair of homologous chromosomes is random=independent assortment (increase gamete diversity)

Question 7

Anaphase 1 (3)

Answer 7

• Spindle fibres shorten pulling homologous chromosomes apart
• sister chromatids remain together so that each new pole has a full set of DNA
• single chromosome (2 chromatid) from each homologous pair moves to each pole of the cell

Question 8

Telephase 1 (4)

Answer 8

• homologous chromosomes begin to uncoil and the spindle fibres disappear
• cytoplasm is divided
• nuclear membrane forms around each group of homologous chromosomes and two cells are formed.
• Each cells is a haploid because they contain either the maternal or paternal set of homologous chromosomes

Question 9

Prophase 2 (3)

Answer 9

• chromosomes visible
• nuclear membrane disappears
• mitotic spindle forms

Question 10

Metaphase 2

Answer 10

• Chromosomes align single file on plate

Question 11

Anaphase 2

Answer 11

• sister chromatids pulled apart to opposite poles

Question 12

Telephase 2

Answer 12

nuclear membrane reform

Question 13

Nondisjunction (3)

Answer 13

• When chromosomes or chromatids do not separate as they should during meiosis
• occurs in anaphase 1 or 2
• produces gametes that have too few or too many chromosomes

Question 14

Nondisjunction in anaphase 1:

Answer 14

• occurs when homologous chromosome pairs do not separate to opposite poles, instead, one entire pair is pulled towards the same pole together

Question 15

Nondisjunction in anaphase 2

Answer 15

• occurs when sister chromatids do not separate to opposite poles instead both sister chromatids are pulled toward the same pole together

Question 16

Monosomy (3)

Answer 16

• gamete is missing one chromosome of a homologous pair
• 45 chromosomes in each cell instead of 46
• 2n=45

Question 17

Trisomy (2)

Answer 17

• the gain of an extra chromosome

- 2n=47

Question 18

Spermatogenesis+ what does it produce (2)

Answer 18

• process of sperm production

- produces four viable sperm

Question 19

oogenesis

Answer 19

• cytoplasm is not equally divided resulting in a single viable ovum and 3 polar bodies