15: Meiosis Flashcards

Module 3, Lesson 4

1
Q

For organisms that perform sexual reproduction, genetic information can be passed on via cycles of ____ and ____.

A

Meiosis and fertilization

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2
Q

Meiosis often involves transitions between ____ and ____ states.

A

Diploid and haploid

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3
Q

Most animal cells are…

A

Diploid

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4
Q

Diploid ____ cells perform meiosis.

A

Germline

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5
Q

The end product of meiosis is ____.

A

Gametes

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6
Q

Are gametes haploid or diploid?

A

Haploid

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7
Q

During sexual reproduction, gametes fuse to produce…

A

A zygote

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8
Q

Are zygotes haploid or diploid?

A

Diploid

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9
Q

A zygote contains both a ____ homologue and a ____ homologue.

A

Maternal ; paternal

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10
Q

A zygote becomes a multicellular organism through the process of…

A

Mitosis

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11
Q

List three ways in which mitosis and meiosis are similar.

A
  1. Both use a microtubule-based spindle machine
  2. Both segregate condensed DNA molecules into two daughter cells
  3. Both include prophase, metaphase, anaphase, and telophase
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12
Q

List the four phases of division that are common to both mitosis and meiosis.

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
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13
Q

List three features of meiosis that are distinct from mitosis.

A
  1. Two rounds of division, but only one round of DNA replication
  2. Synapsis
  3. Crossing over
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14
Q

List the three main phases of meiosis.

A
  1. DNA replication
  2. Meiosis I (first division)
  3. Meiosis II (second division)
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15
Q

Through the process of meiosis I, a diploid germ cell splits into…

A

Two haploid daughter cells

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16
Q

The cells produced in meiosis I have ____ copy(ies) of each chromosome.

A

2

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17
Q

True or false:

The daughter cells replicate their DNA before entering meiosis II.

A

False

These cells suppress their DNA replication.

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18
Q

The daughter cells produced in meiosis II have ____ copy(ies) of each chromosome.

A

1

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19
Q

A tight association between homologous pairs is called…

A

Synapsis

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20
Q

The process by which homologues can exchange segments of their DNA is called…

A

Crossing over

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21
Q

During which phase of meiosis does synapsis occur?

A

Early prophase 1
(in meiosis I)

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22
Q

During synapsis, the homologous chromosomes form a structure called the…

A

Synaptonemal complex

23
Q

The synaptonemal complex is also called…

A

A tetrad or a bivalent

24
Q

How does the synaptonemal complex associate chromosomes?

A

It pairs them along their length using a matrix of connecting proteins

25
Q

Crossing over is possible due to…

A

Synapsis

26
Q

True or false:

Crossing over can only occur between sister chromatids.

A

False

It allows genetic recombination between non-sister chromatids

27
Q

True or false

Because of crossing-over, alleles of genes that were on separate homologues can end up on the same homologue.

A

True

28
Q

The site where crossing over takes place is called…

A

Chiasmata

29
Q

Crossing over generally occus during…

A

Prophase 1

30
Q

Chromosomes remain connected due to synapsis until…

A

Anaphase 1

31
Q

True or false:

Meiotic cells do not go through interphase.

A

False

Meiotic cells do have an interphase (G1, S, and G2) period.

32
Q

What occurs during prophase 1?

(three)

A
  1. Homologous chromosomes associate (synapsis)
  2. Cross-over events occur
  3. Microtubules from opposite poles attach to each homologue
33
Q

What occurs during metaphase 1?

(one)

A

Bivalents congress to the metaphase plate

34
Q

The orientation of homologues on the metaphase plate is random, so…

A

Different combinations of maternal and paternal homologues can be attached to each spindle pole

35
Q

What happens during anaphase 1?

(one)

A

Homologues of each pair separate

36
Q

During anaphase 1, what happens to the sister chromatids?

A

They remain connected

37
Q

What happens during telophase 1?

A

The homologues move to opposite poles

38
Q

After the completion of meiosis I, the two haploid cells formed have…

A

Different combinations of maternal and paternal homologues

39
Q

The varied genetic makeup of the daughter cells produced in meiosis I is known as…

A

Independent assortment

40
Q

True or false:

After meiosis I, the sister chromatids are identical.

A

False

Due to cross-over events, they may no longer be identical.

41
Q

Meiosis I is often called…

A

“Reduction division”

42
Q

Meiosis results in a ____ of chromosomes for each daughter cell.

A

Loss

43
Q

How long after meiosis I ends does meiois II begin?

A

It varies

44
Q

Meiosis II closely resembles ____ division.

A

Mitotic

45
Q

During meiosis II, the ____ are separated.

A

Sister chromatids

46
Q

Each daughter cell produced in meiosis II has one random chromosome from…

A

Each homologous pair

47
Q

True or false:

The daughter cells produced in meiosis II are genetically identical.

A

False

Each cell contains a different set of parental genes.

48
Q

True or false:

In animal cells, daughter cells develop into gametes immediately after the completion of meiosis II.

A

True

49
Q

True or false:

In plants, fungi, and protists; daughter cells develop into gametes immediately after the completion of meiosis II.

A

False

These cells reproduce mitotically to increase their numbers before developing into gametes.

50
Q

____ occurs when chromosomes fail to move to opposite poles during either meiosis I or meiosis II.

A

Nondisjunction

51
Q

Nondisjunction results in ____ gametes, which have missing or extra chromosomes.

A

Aneuploid

52
Q

____ is the most common cause of spontaneous abortion in humans.

Note: spontaneous abortion is when the embryo just dies without any external influence. This is what causes miscarriages.

A

Nondisjunction

This is because having the wrong number of chromosomes is usually fatal to the cell. Exceptions would be things like Down Syndrome.

53
Q

From a species viewpoint, the benefit of increased genetic variation ____ the chance and impact of negative errors.

A

Far outweighs

54
Q

After meiosis is complete, a single parent cell has split into ____ daughter cells.

A

Four