meiosis stage 1

Question 1

when does crossing over happen

Answer 1

-in prophase

Question 2

what is crossing over

Answer 2

-exchanging some alleles between homologous chromosomes by crossing over
-produce chaismata- point where chromosomes r crossed over

Question 3

what is independently sorting

Answer 3

-way in which different homologous chromosomes are randomly distributed into daughter cells during meiosis.

Question 4

what happens in prophase 1

Answer 4

-chromatin condenses and is supercoiled
-nucleur envelope breaks down
-spindle threads of tubulin protein form from centriole
-chromosomes come together in homologous pairs
-crossing over occurs (alleles are shuffled)

Question 5

what happens during metaphase 1

Answer 5

-pairs of homologous chromosomes attach along equator by spindle
-attaches to a spindle thread by its centromere
-the homologous pairs are arranged randomly with the members of each pair facing opposite poles (independent assortment)

Question 6

what happens during anaphase one

Answer 6

-members of each pair of homologous chromosomes are pulled apart by motor proteins along tubulin threads of spindle
-the centromere doesnt divide
-crossed over areas seperate from each other - swapped areas of chromosome and alleles shuffled

Question 7

what happens during telophase 1

Answer 7

-in most animal cells, 2 new nucleur envelops form around each set of chromosome, divide by cytokenesis
-each new nucleus now contains half number of chromosomes but each chromosome consists of 2 chromatids

Question 8

what is the difference in alleles because of crossing over due to

Answer 8

-The difference in alleles is due to recombination between non-sister chromatids of homologous chromosomes, not between the sister chromatids themselves.

Question 9

what is random assortment of chromosomes

Answer 9

-happens during metaphase 1
-when homologous chromosomes align randomly in the equator