mitosis and meiosis

Question 1

what type of cells are produced through meiosis

Answer 1

-gametes
-egg or sperm
-haploid

Question 2

what is a haploid cell

Answer 2

a cell that has one copy of each gene

Question 3

where does meiosis occur

Answer 3

gonads (testes or ovaries)

Question 4

what is it called when meiosis occurs in males

Answer 4

spermatogenesis

Question 5

what is it called when meiosis occurs in females

Answer 5

oogenesis

Question 6

what happens in interphase of meiosis

Answer 6

-G1 cell grows and carries out life processes
-S chromatin replicates and is organized into chromosomes
-G2 Cell prepares for cell division

Question 7

what is meiosis I

Answer 7

-reduces the chromosome number by half
-involves homologous chromosomes

Question 8

what happens in prophase I

Answer 8

-it is the longest and most complex phase
-nuclear membrane dissolves and chromosomes condense
-centrioles make spindle fibres which are attached to to centromeres
-synapsis occurs
-crossing over occurs

Question 9

what is synapsis

Answer 9

process by which homologous chromosomes come together to form a tetrad

Question 10

what is a tetrad

Answer 10

consists of two chromosomes of 4 chromatids (sister and non sister) joined together

Question 11

what are homologous chromosomes

Answer 11

-pair of chromosomes (maternal and paternal) that are similar in shape and size
-homologous pairs (tetrads) carry genes controlling the same inherited traits
-humans have 23 pairs of homologous chromosomes
-22 pairs of autosomes
-1 pair of sex chromosomes (XX, XY)

Question 12

what is crossing over

Answer 12

-leads to variation
-may occur between non sister chromatids
-segments of non sister chromatids break and reattach to the other chromatid

Question 13

what happens in metaphase I

Answer 13

-shortest phase
-tetrads align on the equator
-independent assortment occurs - orientation of homologous pairs is random (allows for more variation)

Question 14

what happens in anaphase I

Answer 14

-homologous pairs separate and move towards poles
-sister chromatids remain attached at their centromeres

Question 15

what happens in telophase I

Answer 15

-each pole now has haploid set of chromosomes
-two new nuclear membranes form
-spindle fibres dissolve and their centrioles duplicate
-cytokinesis occurs and two haploid daughter cells are formed

Question 16

what does not happen in meiosis II

Answer 16

interphase because there is no more DNA replication to be done

Question 17

what happens in prophase II

Answer 17

-DNA condenses into chromosomes
-nuclear membranes disappear
-centrioles move to the poles of the cell
-spindle fibres form
-same as prophase is mitosis

Question 18

what happens in metaphase II

Answer 18

-chromosomes line up in the middle of the cell
-spindle fibres push them there
-same as metaphase in mitosis

Question 19

what happens in anaphase II

Answer 19

-centromeres divide and the sister chromatids separate
-sister chromatids are pulled by spindle fibres to opposite sides of the cell
-same as anaphase in mitosis

Question 20

what happens in telophase II

Answer 20

-centrioles duplicate and spindle fibres disappear
-4 new nuclear membranes form
-cytokinesis occurs
-produces 4 genetically unique haploid daughter cells
-same as telophase in mitosis

Question 21

what does spermatogenesis produce

Answer 21

-4 haploid spedm for every one diploid cell

Question 22

what does spermatogenesis produce

Answer 22

-4 haploid spedm for every one diploid cell

Question 23

what does oogenesis produce

Answer 23

-only 1 mature haploid egg cell and 3 polar bodies for everyone 1 diploid cell
-the polar bodies will be broken down and reabsorbed
-polar bodies donate their nutrients to the egg because after fertilization the zygote doesn’t implant for 7 days

Question 24

what is fertilization

Answer 24

the fusion of a sperm and egg to form a zygote

Question 25

what is a zygote

Answer 25

a fertilized egg

Question 26

what is no disjunction

Answer 26

-failure of chromosomes to separate and segregate into daughter cells
-may occur during meiosis I or meiosis II
abnormal number of chromosomes may result

Question 27

where does non disjunction occur in meiosis I

Answer 27

during anaphase the homologous chromsomes both go to one cell

Question 28

what does nondisjunction in meiosis I result in

Answer 28

two diatomic gametes and two nullisomic gametes

Question 29

where does nondisjunction occur during meiosis II

Answer 29

in anaphase two one pair of sister chromatids fail to separate

Question 30

what does nondisjunction in meiosis II result in

Answer 30

one disomic gamete, one nullisomic gamete, and two monosomic gametes