meiosis - exam 2

Question 1

number of chromosomes in gametes

Answer 1

1n egg + 1n sperm

Question 2

number of chromosomes in zygotes

Answer 2

2n

Question 3

meisosis, fertilization, & mitosis in human life cycle

Answer 3

2n parents –> meiosis –> 1n gametes

fertilization –> 2n zygote

mitosis

Question 4

homologous chromosomes

Answer 4

2 pairs of sister chromatids

Question 5

autosomes

Answer 5

non sex chromosomes

Question 6

allele

Answer 6

alternate versions of the same gene

Question 7

prophase I unique stuff

Answer 7

synapsis occurs

crossing over occurs

Question 8

synapsis

Answer 8

pairing of homologous chromosomes

maternal & paternal come together

Question 9

synaptonemal complex

Answer 9

protein lattice between homologous chromosomes

Question 10

crossing over

Answer 10

exchange of genetic material between non-sister chromatids

1 maternal & 1 paternal

Question 11

recombinant chromatids

Answer 11

new combination of alleles

sometimes genes break during crossing over & get fixed in a different way

Question 12

metaphase I

Answer 12

homologous pairs align on metaphase plate

random alignment = independent assortment

Question 13

anaphase I

Answer 13

kinetochore MTs shortern at the same time as the synaptonemal complex degrades

homologous chromosomes separate & move to opposite sides of cell

sister chromatids stay attached

Question 14

telophase I

Answer 14

each half of cell has complete 1n set of replicated chromosomes

each chromosome = 2 sister chromatids
- 2 haploid cells –> both are n=3

interkinesis

no dna replication

both cells enter meiosis II

Question 15

prophase II

Answer 15

just like mitosis

Question 16

metaphase II

Answer 16

chromosomes aligned on metaphase plate

Question 17

anaphase II

Answer 17

sister chromatids separated –> moved to opposite poles of cell

Question 18

telophase II

Answer 18

chromosomes decondense

nuclei reform

Question 19

meiosis II results in what

Answer 19

four haploid daughter cells (n=3)

Question 20

how does meiosis increase genetic variability

Answer 20

mutation

random alignment of chromosomes on metaphase I plate

crossing over

fertilization

Question 21

nondisjunction

Answer 21

homologous chromosomes or sister chromatids don’t separate from each other

Question 22

how does nondisjunction lead to abnormalities

Answer 22

homologous chromosomes fail to separate

sister chromatids fail to separate