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Biology 2311 > Chapter 11-PowerPoint > Flashcards

Chapter 11-PowerPoint Flashcards

1
Q

Where does meiosis occur?

A

germ-line cells

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2
Q

What ploidy are germ-line cells?

A

diploid

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3
Q

What are the germ-line cells called in meiosis?

A

gonads

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4
Q

What are the gonads in males?

A

testes

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5
Q

What are the gonads in females called?

A

overaries

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6
Q

What is produced in meiosis?

A

sperm and ova

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7
Q

What is the production of sperm and ova called?

A

gametogenesis

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8
Q

What is the ploidy of gametes?

A

haploid

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9
Q

What does fertilization produce?

A

zygote

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10
Q

What is the ploidy of a zygote?

A

diploid

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11
Q

What is variability?

A

mixing gentic information

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12
Q

Where does variability occur (asexual or sexual reproduction)?

A

sexual reproduction

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13
Q

What are the steps in meiosis 1?

A

G1, S, G2, M, I

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14
Q

What are the steps in meiosis 2?

A

G1, G2, M, I

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15
Q

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

A

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

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16
Q

When does crossing over happen?

A

prophase 1 of meiosis 1

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17
Q

What happens in crossing over?

A

homologous chromosomes pair and non sister chromatids exchange chromosomes segments

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18
Q

Which is reduction division?

A

meiosis 1

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19
Q

What is separated in meiosis 1?

A

homologous chromosome

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20
Q

What is separated in meiosis 2?

A

sister chromatids

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21
Q

Where else does separation of sister chromatids?

A

anaphase of mitosis

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22
Q

What is a synapsis?

A

homologues pair along their length

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23
Q

What is Homologous recombination?

A

Genetic exchange (crossing over) occurs between homologous chromosomes.

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24
Q

What is Reduction division?

A

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

meiosis 1

—no S phase

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25
Q

What is the synaptonemal complex?

A

protein that helps connect homologues

26
Q

In homologous chromosomes have the same? what is different?

A

genes are the same, but different sequence

27
Q

What alleles?

A

different version of each gene in a homologous pair

ex. A vs a

28
Q

What does crossing over lead to?

A

diversity

29
Q

What is a chiasmata?

A

site where crossing over has occurred, thickened spots

30
Q

After crossing over will the sister chromatids be identical?

A

no

31
Q

What is equational division?

A

meiosis 2

32
Q

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

A

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

33
Q

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

A

yes, 2n -> n

34
Q

What happens in prometaphase 1?

A
  • 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
35
Q

When does the nuclear envelope start to break down?

A

prophase 1

36
Q

What happens in metaphase 1?

A
  • Terminal chiasmata holds homologous pair together.

- Joined pairs of homologues line up on metaphase plate.

37
Q

Is the orientation of each pair in metaphase 1 random?

A

yes

38
Q

What stage does independent assortment occur?

A

metaphase 1

39
Q

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

A

2^n

40
Q

In humans how many combinations are possible from independent assortment?

A

2^23

41
Q

What happens in anaphase 1?

A
  • 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
42
Q

What happens in telophase 1?

A
  • 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.
43
Q

What is interkinesis?

A

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

44
Q

What happens in Prophase II?

A

Chromosomes condense and a spindle forms

45
Q

What happens in Prometaphase II?

A
  • Nuclear envelope breaks down
  • spindle enters the former nuclear area
  • spindle microtubules attach to the two kinetochores of each chromosome
46
Q

What happens in Metaphase II?

A

Spindle microtubules align chromosomes on the metaphase plate

47
Q

What happens in anaphase II?

A

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

48
Q

What happens in telophase II?

A
  • Chromatids decondense to extended interphase state
  • Spindles disassemble and new nuclear envelopes form around the chromatin
  • creates 4 haploid cells
49
Q

When does nondisjunction occur?

A

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

50
Q

What does nondisjunction result in?

A

zygote will have a extra number of chromosomes

51
Q

What is the male sex chromosome?

A

XY

52
Q

What is the female sex chromsomes?

A

XX

53
Q

In females are the XX chromosomes fully homologous?

A

yes

54
Q

In males are the XY chromosomes fully homologous?

A

No, they are partly homologous

55
Q

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

A

spores

56
Q

What are 3 sources of genetic variability?

A

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

57
Q

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

A

one or more time

58
Q

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?

A

1 out of (2^23)^2

or

1 out around 70 trillion

59
Q

Is the haploid or diploid dominate in animals?

A

diploid

60
Q

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

A

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

61
Q

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

A

haploid

Biology 2311 (16 decks)

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