meiosis

Question 1

what is meiosis?

Answer 1

special type of cell divison that occurs only in reproductive organs.

Question 2

what do meiosis make?

Answer 2

gametes

Question 3

what are the functions of meiosis

Answer 3

meiosis 1: reduction division
meiosis 2: further divide the cell

Question 4

what is the division of chromosome number?

Answer 4

body cells= 46 chromosomes (2n)– diploid
gametes= 23 chromosomes (n)– haploid

Question 5

meiosis– interphase

Answer 5

same as mitosis= cell grows and replicates DNA
= chromosome is made up of a pair of identical sister chromatids held together by a centermer

Question 6

prophase 1

Answer 6

homologous chromosomes align and form a bivalent
nuclear membrane disappears
spindle fibers begin to form
crossing over occurs

Question 7

what so homologous chromosomes contain?

Answer 7

the same genes- but since they came from diff parents they can have different alleles

Question 8

crossing over?

Answer 8

the exchange of genetic material b/w non sister homologous chromatids
may not happen at all

Question 9

what is a bivalent?

Answer 9

the structure of the 2 non sister homologues pairs crossing over

Question 10

what is a bivalent?

Answer 10

the structure of the 2 non sister homologues pairs crossing over, where the sister chromatids may touch and break.

Question 11

the region where crossing over occurs?

Answer 11

chiasma

Question 12

result of crossing over?

Answer 12

chromatids that are a mixture of paternal and maternal alleles. crossing over may happen multiple times between diff chromatids within the same homologous pair.

Question 13

metaphase 1

Answer 13

spindle fibers attach to the centromere of each chromosome
spindle fibers pull each bivalent to the center of the cell
random assortment occurs

Question 14

random assortment?

Answer 14

another way to ensure genetic variability

Question 15

what happens during random assortment

Answer 15

bivalents line up on the equator of the cell randomly
paternal chromosomes// maternal chromosomes= that some gametes will obtain maternal and others will get paternal genes
or, parental chromosomes could be on both sides of the equator= gametes to contain a mixture of maternal and parental chromatids.

Question 16

anaphase 1

Answer 16

The homologous chromosomes separate
and move to opposite poles of the cell.
centromere does not split as in mitosis=sister chromatids are held together, moving one chromosome to each of the poles.

Question 17

telaphase 1

Answer 17

may or may not occur– depends on the type of meiosis is occurring
chromosomes begin to uncoil and the spindle fibers disappear.
The cytoplasm is divided and the nuclear
membrane begins to form around the pairs of
homologous chromosomes.

Question 18

does DNA replication occur in meiosis 2??

Answer 18

no, Because each chromosome already consists of two chromatids,

Question 19

meosis 2

Answer 19

identical to mitosis

Question 20

end product of meiosis

Answer 20

4 non identical haploid cells