Chapter 13: Meiosis and Sexual Life Cycles

Question 1

Heredity

Answer 1

transmission of traits from one generation to the next

Question 2

Variation

Answer 2

difference in inherited traits

Question 3

Genetics

Answer 3

the study of both heredity and inherited variation

Question 4

Genes

Answer 4

hereditary units that hold genetic information

Question 5

Gametes

Answer 5

reproductive cells, vehicles that transmit genes from one generation to the next

Question 6

Somatic Cells

Answer 6

all cells in the body except for gametes

Question 7

Locus

Answer 7

genes specific location along the length of the chromosome

Question 8

Asexual Reproduction

Answer 8

cell passes on its genetic information without the fusion of gametes

Question 9

Clone

Answer 9

individual group/groups of individuals that are genetically identical to the parent

Question 10

Sexual Reproduction

Answer 10

two parent cells give rise to offspring that have a unique combination of genes inherited from the parents

Question 11

Life Cycle

Answer 11

generation to generation sequence of stages in the reproductive history of an organism

Question 12

Karyotype

Answer 12

ordered display of paired chromosomes from longest to shortest

Question 13

Homologous Chromosomes

Answer 13

homologs, 2 chromosomes of a pair that have the same length, centromere position, and staining pattern

Question 14

Sex Chromosomes

Answer 14

the X and Y chromosomes that determine biological gender

Question 15

Autosomes

Answer 15

all other chromosomes

Question 16

Diploid Cell

Answer 16

any cell with 2 chromosome sets (2n)

Question 17

Haploid Cell

Answer 17

gametes, only have one set of chromosomes (n)

Question 18

Fertilization

Answer 18

union of gametes, fusion of two nuclei

Question 19

Meiosis

Answer 19

sex cell division, reduces the number of sets of chromosomes from two in the parent cell to one in the gamete

Question 20

Alterations of Generations

Answer 20

type of life cycle in some algae species that includes both diploids and haploids

Question 21

Sister Chromatid Cohesion

Answer 21

2 copies of one chromosome, closely associated along their lengths

Question 21

Meiosis I and II

Answer 21

two consecutive cell divisions that result in 4 daughter cells with half as many chromosomes as the parent cell

Question 22

Allele

Answer 22

each different version of genes at different loci

Question 23

Meiosis I

Answer 23

separates homologous chromosomes

Question 24

Meiosis II

Answer 24

separates sister chromatids

Question 25

Crossing over and Synapsis in Prophase I

Answer 25

cohesions and 4 steps

Question 26

Cohesions

Answer 26

protein that holds together sister chromatids

Question 27

Step 1 of Crossing Over

Answer 27

2 members of a homologous pair associate loosely, each gene on a homolog is linked up with a corresponding allele of that gene on the other homolog, DNA of 2 nonsister chromatids is broken by specific proteins at the attachment point

Question 28

Step 2 of Crossing Over

Answer 28

zipper-like structure called the synaptonemal complex holds one homolog to another

Question 29

Step 3 of Crossing Over

Answer 29

in this association, called synapsis, the DNA breaks are close and each end is joined to the corresponding joint on the nonsister chromatid, paternal and maternal chromatid are joined beyond the crossover point

Question 30

Step 4 of Crossing Over

Answer 30

points where crossing over occurred before are visible as the chiasmata after the synaptonemal complex is disassembled, homologs move slightly apart but remain attached because of sister chromatid cohesion

Question 31

Meiosis I Events

Answer 31

synapsis & crossing over, alignment of homologous pairs at the metaphase plate, and separation of homologs

Question 32

Synapsis and Crossing Over

Answer 32

in prophase I, duplicated homologs pair up and cross over, neither step occur in prophase of mitosis

Question 33

Alignment of Homologous Pairs at the Metaphase Plate

Answer 33

in metaphase I of meiosis, pairs of homologs are positioned at the metaphase plate instead of individual chromosomes like in mitosis

Question 34

Separation of Homologs

Answer 34

at the anaphase I step of meiosis, duplicated chromosomes of homologous pairs move to opposite poles but sister chromatids of duplicated chromosomes stay attached, unlike how mitosis anaphase separates sister chromatids