Lecture 14 - Sexual Reproduction

Question 1

any one of 2^23 possible
sperm can unite with any one of 2^23 possible sperm for 70 trillion unique combinations (crossing over contributes more variability)

Answer 1

random fertilization

Question 2

2 homologs exchange genetic material resulting in new gene combinations

Answer 2

crossing over

Question 3

what part of meiosis does crossing over take place

Answer 3

Prophase 1

Question 4

when are all possible combinations equally probable

Answer 4

random alignment of chromosome pairs in Metaphase 1

Question 5

what kind of DNA replication is meiosis

Answer 5

single

Question 6

in meiosis human cells are….

Answer 6

diploid

• 2 full sets of chromosomes
• 1 set from each parent

Question 7

most body cells do not participate directly in reproduction

Answer 7

somatic cells

Question 8

specialized cells to produce gametes (eggs and sperm)

Answer 8

germ cells

Question 9

are eggs and sperm haploid or diploid

Answer 9

haploid

Question 10

gametes fuse at fertilization to produce…

Answer 10

new diploid zygote

Question 11

different versions of same gene

Answer 11

alleles

Question 12

cytokinesis only effects ______ gametes

Answer 12

male

Question 13

states of meiosis

Answer 13

Meiosis 1

Meiosis 2

Question 14

stages of Meiosis 1

Answer 14

Prophase 1
Metaphase 1
Anaphase 1
Telophase 1

Question 15

stages of Meiosis 2

Answer 15

Prophase 2
Metaphase 2
Anaphase 2
Telophase 2

Question 16

produces haploid nulcei

Answer 16

Meiosis 2

Question 17

where genetic recombination occurs

Answer 17

Meiosis 1

Question 18

reduces #’s of chromosomes by half (shuffling of genetic info)

Answer 18

Meiosis 1

Question 19

when do cells become haploid

Answer 19

Anaphase 1

Question 20

when, because of crossing over, are the cells not the same

Answer 20

Anaphase 2

Question 21

the egg won’t finish anaphase 2 and telophase 2 until it…

Answer 21

is fertilized with the sperm

Question 22

why is it unnecessary for the female eggs to undergo cytokinesis

Answer 22

instead of going through cytokinesis, it just throws one egg out

Question 23

chromosomes fail to separate at 1st or 2nd meiotic division = gamete with extra or missing chromosome

Answer 23

nondisjunstion

Question 24

gamete with extra chromosome

Answer 24

trisomy

Question 25

gamete with missing chromosome

Answer 25

monosomy

Question 26

most embryos with incorrect chromosome numbers...

Answer 26

cease developing

Question 27

which causes fewer problems, trisomy or monosomy

Answer 27

trisomy

Question 28

increasing woman's age, _______ likelihood of trisomy

Answer 28

increases

Question 29

difference between homologous chromosomes and sister chromatids

Answer 29

homologous: - same gene types, different versions(alleles) - come from different parents (2, get 1 from each parent) - have the exact same amount of genetic information = same size, # nucleotides, types of genes sister chromatids - exact copies of each other that come about through semiconservative DNA replication (interphase)

Question 30

more than or equal to 1 complete set of extra chromosomes

Answer 30

polyploidy

Question 31

when does mitotic spindle pull on either side

Answer 31

metaphase 1

Question 32

single zygote

Answer 32

monozygote

Question 33

2 separate zygotes

Answer 33

dizygotic

Question 34

when does meiosis begin in males

Answer 34

puberty

Question 35

when does meiosis begin in females

Answer 35

before they're even born

Question 36

True/False: ultimately, gonads are the only cells that undergo meiosis

Answer 36

True

Question 37

why do problems with nondisjunction occur earlier in females than males

Answer 37

because of the age of their cells....females cells begin meiosis before they're born and males begin meiosis at puberty

Question 38

difference between homologous chromosomes

Answer 38

the alleles

Question 39

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring

Answer 39

crossing over

Question 40

states that the alleles for a trait separate when gametes are formed

Answer 40

independent assortment

Question 41

NOT genetic recombination, its when a mistake happens

Answer 41

Nondisjunction

Question 42

when does crossing over occur

Answer 42

prophase 1

Question 43

when does independent assortment occur

Answer 43

metaphase 1

Question 44

when does nondisjunction occur

Answer 44

anaphase 1 or 2

Question 45

when homologous pairs of chromosome errors exchange equal amounts of genetic info(alleles) and recombine what alleles they have

Answer 45

crossing over

Question 46

how the homologous pairs line up along the middle | - depends randomly what side they line up on = mixes and matches all homologous chromosomes your parents gave you

Answer 46

independent assortment

Question 47

failure of homologous chromosomes(anaphase 1) or sister chromatids(anaphse 2) to separate from each other

Answer 47

nondisjunction

Question 48

three types of genetic recombination that occur in sexual reproduction

Answer 48

- crossing over - independent assortment - fertilization

Question 49

when sperm and egg fertilize each other

Answer 49

type of genetic recombination

Question 50

when does fertilization in females occur

Answer 50

right in the middle of meiosis 2

Question 51

fertilization in males occur

Answer 51

after meiosis 2, it has to finish before sperm can mature

Question 52

difference between monozygotic and dizygotic twins

Answer 52

monozygotic: - have to be same sex - genetics = exact same dizygotic: - 2 separate fertilization events

Question 53

when either homologous chromosomes or sister chromatids fail to separate = 1 more or 1 less chromosome

Answer 53

nondisjunction - most of the time = fatal

Question 54

most common form of autosomal nondisjunction

Answer 54

trisomy nondisjunction/down syndrom

Question 55

which of the following are examples of trisomy in the autosomes - kleinfelter syndrome - down syndrome - triple x syndrome - turner syndrome

Answer 55

down syndrome

Question 56

True/False: nondisjunction is most common in sex cells

Answer 56

True

Question 57

the only monosomy nondisjunction that we've seen to have 1% survival rate

Answer 57

turner syndrome

Question 58

True/False: you can survive without an '"x" chromosome

Answer 58

FALSE! You have to have an x chromosome to live

Question 59

``` which of the following is not an example of nondisjunction? - - - - barbody ```

Answer 59

barbody = x chromosome inactivaton

Question 60

True/False: After meiosis 1 cells are already haploid

Answer 60

True