Meiosis Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

How many chromosomes are there in humans?

A

23

Each pair lines up and separates independently during meiosis I.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a gene?

A

An inherited factor (region of DNA) that helps determine a characteristic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an allele?

A

One of two or more alternative forms of a gene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a locus?

A

A specific place on a chromosome occupied by an allele.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a genotype?

A

A set of alleles possessed by an individual organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a heterozygote?

A

An individual organism possessing two different alleles at alocus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a homozygote?

A

An individual organism possessing two of the same alleles at a locus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a phenotype?

A

The appearance or manifestation of a characteristic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a characteristic?

A

An attribute or feature possesed by an organism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What occurs during interphase?

A

DNA synthesis and chromosome replication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In meiosis I, homologous chromosomes separate. How is the chromosome number affected?

A

It is reduced by half.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What separates in meiosis II?

A

Sister chromatids.

This is known as equatorial division.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

True or false: homologous chromosomes are similar, but no identical.

A

True.

Each homolog carries the asme genes in the same order, but the allelets for each trait may not be the same.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the term for the point on a chromsome by which it is attached to a spindle fiber during cell division?

A

Centromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a chromatid?

A

Two daughter strands of a duplicated chromosome that are joined by a single centeromere and separate during cell divisio to become individual chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In prophase I, synapsis of homologous chromosomes occurs. What is synapsis?

A

Close pairing of homologous chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a tetrad?

A

Closely associated four-sister chromatids of two homologous chromosomes.

18
Q

What is the first mechanism of generating genetic variation in newly formed gametes?

A

Crossing over.

19
Q

What is the second mechanism of generating genetic variation in the newly formed gametes?

A

Anaphase I.

The homologous chromosomes are randomly distributed into two newly divided cells.

20
Q

When does crossing over take place?

A

Late prophase I

21
Q

What is a disadvantage of corssing over?

A

It can result in unequal exchange of genetic material producing chromosomes with deleted or duplilcaed regions.

22
Q

Crossing over is essential for meiosis. Why is so essential?

A

Crossing over is essential for the normal segregation of chromosomes during meiosis.

It also adds additional genetic variation.

23
Q

Crossover is ___ across the centromere.

A

Independent

24
Q

Crossing over is proportional to ____.

A

distance

25
Q

What are the consequences of meiosis and genetic variation?

A

Four cells are produced from each original cell.

Chromosome number in each new cell is reduced by half (haploid cells are made).

Newly formed cells from meiosis are genetically different from one another and from the parental cell.

26
Q

What even takes place in meiosis II, but not in meiosis I?

A. Crossing over

B. Contraction of chromosomes

C. Separation of homologus chromosomes

D. Separation of chromatids

A

D. Separation of chromatids

27
Q

Cell division occurs in:

A. Mitosis

B. Meiosis I

C. Meiosis II

D. B & C

A

D. Meiosis I & II

28
Q

Chromosome reduction occurs in:

A. Mitosis

B. Meiosis I

C. Meiosis II

D. All of the above

A

B. Meiosis I

29
Q

Genetic variation occurs in:

A. Mitosis

B. Meiosis I

C. Meiosis II

A

B. Meiosis I

30
Q

Crossing over occurs in:

A. Mitosis

B. Meiosis I

C. Meiosis II

A

B. Meiosis I

31
Q

Random distribution of maternal and paternal chromosomes occurs in:

A. Meiosis I

B. Meiosis II

C. Mitosis

A

A. Meiosis I

32
Q

What occurs during metaphase of mitosis?

A

Individual chromosomes line up

33
Q

What occurs during meiosis I?

A

Homologous pairs line up

34
Q

What occurs during meiosis II?

A

Individual chromosomes line up

35
Q

What occurs during anaphase of mitosis?

A

Chromatids separate

36
Q

What occurs during anaphase of meiosis I?

A

Homologous chromosomes separate

37
Q

What occur during anaphase of meiosis II?

A

Chromatids separate

38
Q

What is cohesin?

A

A protein complex that holds the chromatids together and is key to the behavior of chromosomes in mitosis and meiosis.

39
Q

When sister chromatids separate during mitosis, the breakdown of what protein occurs?

A

Cohesin

40
Q

What is a primary function of meiosis?

A

To produce haploid gametes.