Lec 4-2

Question 1

Mitosis is

Answer 1

Cell reproduction

1 Haploid—> 2 Haploid cells

or

1 diploid–> 2 diploid

1 cell division

Question 2

Meiosis is

Answer 2

Production of gametes for sexual reproduction

2 cell divisions

1 diploid –> 4 haploid cells

Question 3

Sexual reproduction has 2 steps

Answer 3

Meiosis and fertilization

Question 4

Fertilization

Answer 4

Merger of sperm and egg that produces a diploid organism

Question 5

Meiosis 1 is

Answer 5

Reduction division

Reduces number of chromosomes

Question 6

Meiosis 2 is

Answer 6

Equational division

No reduction in chromosome n

similar to mitosis

Question 7

Prophase 1

event similar to mitosis

Answer 7

Chromosomes condense

Mitotic spindle forms

Nuclear envelope breaks down

Question 8

Prophase 1

Events unlike mitosis

Answer 8

Homologous chromosomes pair up and physically associate (are not independent)

Leads to crossing over (key to genetic diversity)

Question 9

Leptotene

Prophase 1

Answer 9

Chromosomes condense using condensin

Process occurs continuously

Question 10

Zygotene

Prophase 1

Answer 10

When synapsis starts (close pairing of homologous chromosomes)

Question 11

Bivalent or tetrad

Answer 11

Four chromatids undergoing synapsis

Question 12

Synaptonemal complex

prophase 1

Answer 12

Protein structure that scaffolds interacting chromatids (thought to facilitate crossing over)

Question 13

Crossing over

Answer 13

Segments from one sister chromatid “cross over” the other sister chromatid at points called chiasmata

Creates genetic variation

Question 14

Rest of meiosis 1

Metaphase 1

Answer 14

Similar to mitosis

Align at the metaphase plate

However, homologous pairs are physically associated, so align together, not as single chromosomes in Mitosis

Question 15

Interkinesis stage

Answer 15

Nuclear membrane reforms around chromosomes

Spindle breaks down

Chromosomes relax

Question 16

Meiosis 2

Answer 16

All phases are the same as mitosis except these occur to two cells

Question 17

Product of meiosis

Answer 17

4 daughter cells that are genetically different from each other and parent cells

Question 18

Females create

Answer 18

Secondary oocyte through meiosis, which combines with sperm to create a zygote

Question 19

Zygote

Answer 19

Eukaryotic cell formed by fertilization between two gametes

Question 20

Gametophyte

Answer 20

Generates gametes for fertilization

Spores develop into gametophytes through multiple rounds of mitosis

Question 21

Sporophyte

Answer 21

Multicellular diploid organism that makes spores

Question 22

Spores

Answer 22

Haploid cells produced by sporophyte