chapter 12 - mitosis never ends apparently

Question 1

asexual reproduction

Answer 1

single parent produces offspring; all offspring are genetically identical to one another and to the parent. easy, rapid colonization

Question 2

allele

Answer 2

a molecular variant of a gene
- offspring inherit new combinations of alleles, which leads to variations in traits (BASIS OF EVOLUTIONARY CHANGE)

Question 3

homologous chromosomes

Answer 3

pairings of the same chromosomes; 1 from each parent. paternal and maternal chromosomes often carry different alleles

Question 4

locus

Answer 4

(pl. loci) where an allele is found on a chromosome

Question 5

gametes are ___________, while gonads are ____________.

Answer 5

sex cells; organs that produce them

Question 6

germ cells

Answer 6

another term for reproductive cells; they are diploid (2n) while gametes are haploid (n)

Question 7

when does dna replicate during meiosis?

Answer 7

in meiosis, dna is not duplicated before meiosis I and IS duplicated replicated before meiosis II
- goal is to cut the end chromosome number in half and produce genetically diverse offspring

Question 8

meiosis i

Answer 8

each replicated chromosome pairs with its homologous partner

Question 9

meiosis ii

Answer 9

sister chromatids separate and the chromosomes are sorted into

Question 10

metaphase i

Answer 10

homologous chromosomes line up in pairs

Question 11

anaphase i

Answer 11

homologous chromosomes separate in pairs
sister chromatids remain intact

Question 12

telophase i

Answer 12

haploid cell, goes immediately into prophase ii

Question 13

crossing over

Answer 13

• homologues exchange segments (non-sisters)
• parental and maternal are present in each chromosome
• effect: offspring have new allele combinations

Question 14

random alignment

Answer 14

either maternal or paternal chromosomes can end up on either pole (metaphase)
- the lineup of pairs is random
2^n = 8,388,606 combinations

Question 15

polar body

Answer 15

the “eggs” formed during meiosis that end up dying as meiosis is very uneven

Question 16

fertilization

Answer 16

• male and female gametes unite and nuclear fuse
• fusion of two haploid nuclei produces diploid nucleus in the zygote
• the two gametes that unite are random
• adds even more variation among offspring

Question 17

variation summary

Answer 17

crossing over during prophase i
random alignment of chromosomes at metaphase i
random combinations of gametes at fertilization

Question 18

differences in prophase

Answer 18

mitosis: homologous pairs do not interact
meiosis (prophase i): homologous pairs become zippered together and crossing over occurs

Question 19

differences in anaphase

Answer 19

mitosis: sister chromatids of a chromosome separate from each other
meiosis (anaphase i) homologous chromosomes separate from each other
(anaphase ii): sister chromatids of a chromosome separate from each other