Chapter 11-PowerPoint

Question 1

Where does meiosis occur?

Answer 1

germ-line cells

Question 2

What ploidy are germ-line cells?

Answer 2

diploid

Question 3

What are the germ-line cells called in meiosis?

Answer 3

gonads

Question 4

What are the gonads in males?

Answer 4

testes

Question 5

What are the gonads in females called?

Answer 5

overaries

Question 6

What is produced in meiosis?

Answer 6

sperm and ova

Question 7

What is the production of sperm and ova called?

Answer 7

gametogenesis

Question 8

What is the ploidy of gametes?

Answer 8

haploid

Question 9

What does fertilization produce?

Answer 9

zygote

Question 10

What is the ploidy of a zygote?

Answer 10

diploid

Question 11

What is variability?

Answer 11

mixing gentic information

Question 12

Where does variability occur (asexual or sexual reproduction)?

Answer 12

sexual reproduction

Question 13

What are the steps in meiosis 1?

Answer 13

G1, S, G2, M, I

Question 14

What are the steps in meiosis 2?

Answer 14

G1, G2, M, I

Question 15

What are the differences in the steps of meiosis 1 vs meiosis 2?

Answer 15

Meiosis 2 doesn’t have an S phase and the G1 and G2 phases are shorter

Question 16

When does crossing over happen?

Answer 16

prophase 1 of meiosis 1

Question 17

What happens in crossing over?

Answer 17

homologous chromosomes pair and non sister chromatids exchange chromosomes segments

Question 18

Which is reduction division?

Answer 18

meiosis 1

Question 19

What is separated in meiosis 1?

Answer 19

homologous chromosome

Question 20

What is separated in meiosis 2?

Answer 20

sister chromatids

Question 21

Where else does separation of sister chromatids?

Answer 21

anaphase of mitosis

Question 22

What is a synapsis?

Answer 22

homologues pair along their length

Question 23

What is Homologous recombination?

Answer 23

Genetic exchange (crossing over) occurs between homologous chromosomes.

Question 24

What is Reduction division?

Answer 24

Meiosis involves two successive divisions, with no replication of genetic material between them.

meiosis 1

—no S phase

Question 25

What is the synaptonemal complex?

Answer 25

protein that helps connect homologues

Question 26

In homologous chromosomes have the same? what is different?

Answer 26

genes are the same, but different sequence

Question 27

What alleles?

Answer 27

different version of each gene in a homologous pair | ex. A vs a

Question 28

What does crossing over lead to?

Answer 28

diversity

Question 29

What is a chiasmata?

Answer 29

site where crossing over has occurred, thickened spots

Question 30

After crossing over will the sister chromatids be identical?

Answer 30

no

Question 31

What is equational division?

Answer 31

meiosis 2

Question 32

Does the second meiotic division further reduce the number of chromosomes?

Answer 32

no, n -> n (just separating sister chromatids)

Question 33

Does the first meiotic division further reduce the number of chromosomes?

Answer 33

yes, 2n -> n

Question 34

What happens in prometaphase 1?

Answer 34

- nuclear envelope breaks down completely - spindle enters the former nuclear area - The two chromosomes of each pair attach to kinetochore microtubules leading to opposite spindle poles - Sister chromatids remain attached to each other

Question 35

When does the nuclear envelope start to break down?

Answer 35

prophase 1

Question 36

What happens in metaphase 1?

Answer 36

- Terminal chiasmata holds homologous pair together. | - Joined pairs of homologues line up on metaphase plate.

Question 37

Is the orientation of each pair in metaphase 1 random?

Answer 37

yes

Question 38

What stage does independent assortment occur?

Answer 38

metaphase 1

Question 39

How many combinations does the variation of orientation in metaphase 1 lead to?

Answer 39

2^n

Question 40

In humans how many combinations are possible from independent assortment?

Answer 40

2^23

Question 41

What happens in anaphase 1?

Answer 41

- Spindle fibers begin to shorten and pull whole centromeres toward poles. - The two chromosomes of each homologous pair separate and move to opposite spindle poles as the spindle microtubules contract - Each chromosome still has two sister chromatids - Random orientation results in independent assortment

Question 42

What happens in telophase 1?

Answer 42

- Chromosomes are segregated into two clusters; one at each pole. - Nuclear membrane re-forms around each daughter cell. - nucleolus starts to appear - Sister chromatids are no longer identical due to crossing over.

Question 43

What is interkinesis?

Answer 43

the single spindle of the first meiotic division disassembles and microtubules reassemble into two new spindles for the second division

Question 44

What happens in Prophase II?

Answer 44

Chromosomes condense and a spindle forms

Question 45

What happens in Prometaphase II?

Answer 45

- Nuclear envelope breaks down - spindle enters the former nuclear area - spindle microtubules attach to the two kinetochores of each chromosome

Question 46

What happens in Metaphase II?

Answer 46

Spindle microtubules align chromosomes on the metaphase plate

Question 47

What happens in anaphase II?

Answer 47

Spindles separate the two chromatids of each chromosome and pull them to opposite spindle poles

Question 48

What happens in telophase II?

Answer 48

- Chromatids decondense to extended interphase state - Spindles disassemble and new nuclear envelopes form around the chromatin - creates 4 haploid cells

Question 49

When does nondisjunction occur?

Answer 49

When homologous chromosomes or sister chromatids do not separate correctly in meiosis 1 or 2

Question 50

What does nondisjunction result in?

Answer 50

zygote will have a extra number of chromosomes

Question 51

What is the male sex chromosome?

Answer 51

XY

Question 52

What is the female sex chromsomes?

Answer 52

XX

Question 53

In females are the XX chromosomes fully homologous?

Answer 53

yes

Question 54

In males are the XY chromosomes fully homologous?

Answer 54

No, they are partly homologous

Question 55

What does meiosis in plants, fungi, and algae produce?

Answer 55

spores

Question 56

What are 3 sources of genetic variability?

Answer 56

crossing over, independent assortment, unique sets of male and female gametes

Question 57

How many times can crossing over occur on the same chromosome pair?

Answer 57

one or more time

Question 58

In the random/unique joining of male and female gametes what are the chances that two children of the same parents receive the same combination of chromosomes?

Answer 58

1 out of (2^23)^2 or 1 out around 70 trillion

Question 59

Is the haploid or diploid dominate in animals?

Answer 59

diploid

Question 60

Is the haploid or diploid dominate in all plants, and some algae and fungi?

Answer 60

they alternate (about 1/2 and 1/2)

Question 61

Is the haploid or diploid dominate in some algae and fungi?

Answer 61

haploid