Ch 13: Meiosis

Question 1

heredity

Answer 1

transmission of traits from one generation to the next

Question 2

variation

Answer 2

shows that offspring differ in appearance from parents & siblings

Question 3

genetics

Answer 3

study of heredity & variation

Question 4

genes

Answer 4

units of heredity; segments of DNA

Question 5

each gene has a specific _______ on a certain chromosome

Answer 5

locus

Question 6

how are chromosomes inherited

Answer 6

one set is inherited from each parent

Question 7

asexual reproduction

Answer 7

one parent produces genetically identical offspring by mitosis

Question 8

sexual reproduction

Answer 8

2 parents = offspring that have unique combos of genes

Question 9

how many human somatic cells are there in the body

Answer 9

46 chromosomes
2 sets of 23

Question 10

karyotype

Answer 10

ordered display of pairs of chromosomes from a cell

Question 11

homologous chromosomes (homologues)

Answer 11

2 chromosomes in each pair

Question 12

how do homologues work

Answer 12

both chromosomes carry genes that control the same inherited characteristics

Question 13

autosomes

Answer 13

22 pairs of chromosomes that do not determine sex

Question 14

diploid

Answer 14

2n = 46

Question 15

haploid

Answer 15

n = 23

Question 16

_____ are the only type of human cells produced by meiosis

Answer 16

gametes

Question 17

fertilization

Answer 17

fusing of gametes

Question 18

what does fertilization produce

Answer 18

zygote

Question 19

sporphyte

Answer 19

makes haploid spores by meiosis

Question 20

gametophyte

Answer 20

spore grows into gametophyte by mitosis

Question 21

a gametophyte makes _____ by mitosis

Answer 21

haploid gametes

Question 22

life cycle in plants

Answer 22

• 2 multicellular generations/stages
• one diploid
• one haploid

Question 23

life cycle in fungi

Answer 23

• zygote is only diploid stage
• no multicellular diploid stage

Question 24

zygote produces _____ by meiosis (fungi)

Answer 24

haploid cells

Question 25

depending on type of life cycle

Answer 25

either haploid or diploid can divide by mitosis

Question 26

only _____ can undergo meiosis

Answer 26

diploid cells

Question 27

what contributes to genetic variation in offspring

Answer 27

chromosome halving & doubling

Question 28

2 sets of cell division in meiosis

Answer 28

meiosis I & meiosis II

Question 29

what do the two cell divisions result in

Answer 29

4 daughter cells

Question 30

each daughter cell has ____ has many chromosomes as the parent cell

Answer 30

half

Question 31

meiosis I

Answer 31

homologues separate

Question 32

what does meiosis I result in

Answer 32

2 haploid daughter cells with replicated chromosomes

Question 33

meiosis II

Answer 33

sister chromatids separate

Question 34

what does meiosis II result in

Answer 34

4 haploid daughter cells with unreplicated chromosomes

Question 35

Interphase

Answer 35

- chromosomes are replicated to from sister chromatids - identical sisters are joined at centromere - centrosome replicates

Question 36

4 stages of Meiosis I

Answer 36

Prophase I Metaphase I Anaphase I Telophase I

Question 37

Prophase I

Answer 37

- chromosomes condense - synapsis - crossing over - tetrad is formed

Question 38

synapsis

Answer 38

homologous chromosomes loosely pair up

Question 39

how are homologous chromosomes paired up during synapsis

Answer 39

aligned by genes

Question 40

crossing over

Answer 40

nonsister chromatids exchange DNA segments

Question 41

tetrad

Answer 41

a group of 4 chromatids

Question 42

chiasmata

Answer 42

X shaped regions in tetrads where crossing over occurs

Question 43

Metaphase I

Answer 43

- tetrads line up at metaphase plate - microtubules attach to kinetochore of one chromosome of each tetrad

Question 44

Anaphase I

Answer 44

- pairs separate - each chromosome to each pole - sis chromatids are still attached at centromere

Question 45

Telophase I

Answer 45

- each chromosome still consists of 2 sister chromatids

Question 46

is there any replication between Meiosis I & Meiosis II

Answer 46

no

Question 47

why is there no replication after Meiosis I

Answer 47

chromosomes are already replicated

Question 48

Prophase II

Answer 48

- spindle apparatus forms - chromosomes move toward metaphase plate

Question 49

what is meiosis II similar to

Answer 49

mitosis

Question 50

Metaphase II

Answer 50

- sisters are in the middle - 2 sisters are not genetically identical anymore - kinetochores attach to microtubules

Question 51

Anaphase II

Answer 51

- sisters separate - individual chromosome goes to each pole

Question 52

Telophase II

Answer 52

- nuclei forms - chromosome begins decondensing

Question 53

at the end of meiosis

Answer 53

4 daughter cells each with a haploid set of unreplicated chromosomes

Question 54

each daughter cell is ______ from the others and parent cell

Answer 54

genetically distinct

Question 55

Mitosis vs. Meiosis

Answer 55

- mitosis = genetically identical cells to parents - meiosis produces cells that differ genetically

Question 56

Mitosis _____ the number of chromosomes while Meiosis ______

Answer 56

conserves reduces

Question 57

events unique to Meiosis I

Answer 57

- synapsis & crossing over - tetrads - homologous chromosomes instead of sister chromatids in anaphase I

Question 58

when does synapsis & crossing over occur

Answer 58

prophase I

Question 59

mutations

Answer 59

changes in an organisms DNA - og source of genetic diversity

Question 60

3 mechanisms of genetic variation

Answer 60

- independent assortment - crossing over - random fertilization

Question 61

independent assortment

Answer 61

homologous chromosomes orient randomly at metaphase I of meiosis

Question 62

how many possible combinations for humans?

Answer 62

2^23 = 8 million

Question 63

crossing over

Answer 63

combo of genes inherited from each parent

Question 64

random fertilization

Answer 64

any sperm can fuse with any egg (ovum)