cell division - meiosis

Question 1

importance of meiosis ?

Answer 1

sexual reproduction, increases variation by combing the genetic variation of 2 organisms of the same species

Question 2

what is meiosis ?

Answer 2

production of 4 genetically haploid gametes

Question 3

prophase 1 ?

Answer 3

chromosomes condense, centrioles duplicate and move towards opposite poles
duplicated centrioles
condensed chromosomes
nuclear membrane breaks down
homologous chromosomes pair up and exchange fragments

crossing over of the genetic material/alleles between homologous chromosomes. this creates new combinations of alleles

Question 4

metaphase 1 ?

Answer 4

chromsomes line up at the equator of cell in homologous pairs and spindle fibres form - done by independent segregation / random assortment

Question 5

anaphase 1 ?

Answer 5

chromsomes are pulled to opposite ends of the cell by spindle fibres
sister chromatids stay together
centromere is stll intact

Question 6

telophase 1 ?

Answer 6

nuclear membrane may reform (chromosomes ma condense)
sometimes cytokenisis takes place
newly forming cells are haploid, 2 genetically different sister chromatids

Question 7

prophase 2 ?

Answer 7

centrioles replicate and move to opposite poles
nuclear membrane breaks down

Question 8

metaphase 2 ?

Answer 8

centrioles move to opposite poles
spindle fibres form
chromosomes line up at the equator

Question 9

anaphase 2

Answer 9

centromere divides
chromatids are moved to opposite ends of the cell by spindle fibres

Question 10

telophase 2 ?

Answer 10

nuclear membranes reform
decondense
cytokenesis follows

Question 11

why is meiosis sometimes reffered to as reduction division ?

Answer 11

number of chromosomes are halved

Question 12

decribe 2 ways in which meiosis causes genetic variation ?

Answer 12

homologous chromsomes pair up and exchange fragments, they cross over and recombine to create new pairs
independent assortment - the random allocation of the chromsomes.