Meiosis, Gamete Formation Flashcards

1
Q

How many stages of Meiosis are there? What are they?

A
  1. Meiosis I and Meiosis II
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2
Q

What happens before Meiosis I?

A

All chromosomes duplicate

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3
Q

What happens to the nuclear membrane during Prophase I?

A

It breaks down

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4
Q

What happens w/ the spindle fibers during Prophase I?

A

They start to form

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5
Q

What happens in Prophase I with the replicated chromosomes?

A

Each replicated chromosome joins with its pair to form a group of four sister chromatids

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6
Q

What is the group of chromosomes formed in Prophase I called?

A

A tetrad

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7
Q

What is the pairing process that forms tetrads in Prophase I called?

A

Synapsis

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8
Q

What may happen to the homologous chromosomes while the chromosomes are in tetrad formation?

A

Twist around each other and exchange segments of chromosomes

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9
Q

What is the segment exchange between chromosomes during synapsis called?

A

crossing over

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10
Q

What happens to the chromosomes during Metaphase I?

A

They line up in the center of the cell in tetrad formation

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11
Q

What happens to the spindle fibers during Metaphase I? Where?

A

They attach to the tetrads at their centromeres

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12
Q

What is disjunction?

A

When the homologous pairs separate and move to opposite sides of the cell.

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13
Q

When does disjunction happen?

A

Anaphase I

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14
Q

The two cells that result from Meiosis I are diploid or haploid?

A

Haploid

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15
Q

Why does the cell need to divide again after Meiosis I?

A

Because the chromosomes are each still double stranded.

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16
Q

What happens during Telophase I and Cytokinesis?

A

The cell divides into two new, haploid cells

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17
Q

How many chromosomes do the two cells that resulted from Meiosis I have?

A

Half the number of chromosomes as the original

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18
Q

What happens during Prophase II?

A

Each daughter cell forms spindle fibers and the chromosomes move toward the middle of the cell

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19
Q

What happens during Metaphase II?

A

The chromosomes line up in the center, one by one, of both daughter cells and the spindle fibers attach to their centromeres

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20
Q

What happens during Anaphase II?

A

The two chromatids separate, each becoming a single stranded chromosome and they move to opposite sides of the cell

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21
Q

What happens to the nuclear membrane during Telophase II/Cytokinesis?

A

It reforms

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22
Q

What happens to the cells during Telophase II/Cytokinesis?

A

They divide, forming 4 haploid cells

23
Q

What happens to the chromosomes during Telophase II/Cytokinesis?

A

They change back to chromatin

24
Q

Where do gametes develop?

A

The gonads

25
Q

What are the female gonads and gametes?

A

Ovaries, and egg cells, or ova

26
Q

What are the male gonads and gametes?

A

Testes, sperm

27
Q

What is gametogenesis?

A

the process by which gametes develop in the gonads

28
Q

What is oogenesis?

A

the process of ovum formation which occurs in the ovaries

29
Q

What is a hermaphrodite?

A

Organisms in which there is no separate male or female gender. they have both testes and ovaries

30
Q

Examples of hermaphrodite organisms

A

Earthworms, snails, and other slow moving organisms

31
Q

Do hermaphrodites self fertilize?

A

No-they will exchange sperm and use the other’s to fertilize their own eggs

32
Q

How does oogenesis begin?

A

With oogonia, a type of diploid cells

33
Q

What do the oogonia develop into? When?

A

Cells called primary oocytes. prenatally

34
Q

What stage are the primary oocytes in at time of birth?

A

Prophase of meiosis I. They then enter a resting phase.

35
Q

What happens after a female goes through puberty to the primary oocytes?

A

It completes Meiosis I once a month

36
Q

What does Meiosis I of the primary oocyte form every month?

A

Two cells, a polar body and secondary oocyte.

37
Q

What is the polar body that resulted from Meiosis I of the primary oocyte?

A

a small, nonfunctional cell

38
Q

Which of the two resulting cells of female Meiosis I (the polar body and secondary oocyte) is larger? What did this result in?

A

The secondary oocyte. It therefore receives most of the cytoplasm.

39
Q

What occurs at fertilization?

A

Meiosis II

40
Q

What happens when Meiosis II occurs to the secondary oocyte?

A

The secondary oocyte divides into an ootid and a polar body.

41
Q

What may happen to the polar body that resulted from Meiosis II of the secondary oocyte?

A

It may split into 2 polar bodies

42
Q

What happens to the female polar bodies?

A

They die

43
Q

What happens to the ootid?

A

It grows into a mature egg

44
Q

What is spermatogenesis?

A

process of forming sperm that occurs in the testes

45
Q

What does spermatogenesis begin with?

A

Spermatogonia (diploid cells that a man is born with)

46
Q

What happens to the spermatogonia throughout the life of a male?

A

They divide by mitosis to form more of them

47
Q

What happens to some spermatogonia?

A

They enlarge, become primary spermatocytes

48
Q

What happens to the primary spermatocytes?

A

They go through meiosis I, form 2 cells of equal sizes called secondary spermatocytes?

49
Q

What happens to each secondary spermatocyte?

A

It goes through meiosis II to form four equal sized cells called spermatids

50
Q

What happens to spermatids?

A

They grow tails and become sperm cells

51
Q

What’s the difference in chromosome number between mitosis and meiosis?

A

Diploid for mitosis, haploid meiosis

52
Q

What’s the difference in chromosome distribution between mitosis and meiosis?

A

mitosis-daughter cells have same number and type as parent cells. meiosis-daughter cells have 1 chromosome from each homologous pair and each chromosome is different due to crossing over

53
Q

What’s the difference in function of cells produced between mitosis and meiosis?

A

mitosis-additional body cells for growth, and for unicellular or simple multicellular organisms, it’s a form of asexual reproduction. meiosis produces gametes.

54
Q

Homologous chromosomes

A

one of a pair of chromosomes that match up at meiosis