meiosis

Question 1

meiosis produces…

Answer 1

gametes (sex cells) with 23 chromosomes

Question 2

define meiosis

Answer 2

division process that prevents “doubling” of genetic material from occurring

Question 3

fertilization

Answer 3

fusion of 2 gametes (male + female) to create a diploid cell (develops into new individual)

Question 4

stages of meiosis

Answer 4

1. S phase/interphase
2. meiosis I
3. meiosis II

Question 5

interphase/S-phase

Answer 5

• DNA replication
• each chromosome made of sister chromatids held with centromere

Question 6

meiosis I

Answer 6

number of chromosomes reduced from diploid 2n to haploid n

Question 7

meiosis II

Answer 7

cells are haploid

Question 8

prophase I

Answer 8

• chromosomes condense/shorten
• spindle fibers form
• centrioles move to poles
• homologous chromosomes form tetrad and do synapsis

Question 9

synapsis

Answer 9

• also called crossing over
• chromatids swap ends
• location is called chiasma

Question 10

metaphase I

Answer 10

• tetrads line up at equator (two rows)
• spindle fibers attach to a whole chromosome

Question 11

independent assortment

Answer 11

• random alignment of maternal/paternal chromosomes during metaphase I
• daughter cell can receive either chromosome (maternal or paternal) of each pair

Question 12

anaphase I

Answer 12

• entire pairs of chromosomes pulled to separate sides (sister chromatids do not break apart)

Question 13

telophase I

Answer 13

• chromosomes condense slightly
• cytokinesis forms two genetically diff. daughter cells
• each daughter cell has haploid chromosome (n=2)

Question 14

differences between meiosis I and II

Answer 14

• meiosis II more similar to mitosis but w/o chromosome duplication during a short interphase
• meiosis II: sister chromatids split apart
• meiosis II: final 4 daughter cells

Question 15

prophase II

Answer 15

• nuclear envelope begins to break down
• spindle fibers form
• centriole move to opposite poles

Question 16

metaphase II

Answer 16

• chromosomes align along equator
• spindle fibers attach to centromeres

Question 17

anaphase II

Answer 17

• spindle fibers pull sister chromatids apart

Question 18

telophase II

Answer 18

• nuclear envelope formed
• chromosomes decondense
• spindle fibers disappear
• cytokinesis divides cell in two

Question 19

results of meiosis

Answer 19

• 4 haploid gamete cells (n=2)
• 1 copy of each chromosome (from mom or dad)
• 1 allele of each gene
• different combinations of alleles for different genes along chromosome

Question 20

when does meiosis occur?

Answer 20

• at sexual maturity (eggs produced while still embryo)