MCBG - Mitosis And Meiosis Flashcards

1
Q

True or false - one chromosome can be either one OR two DNA molecules?

A

True - a replicated chromosome is two DNA molecules rather than the usual one.

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2
Q

What are the names given to the arms of chromosomes?

A

P (short) and Q (long) arms

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3
Q

What are telomeres?

A

Repeated sequences at each end of a chromosome/chromatid.

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4
Q

Where is a metacentric centromere placed on the chromosome?

A

In the middle.

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5
Q

True or false - all of a human’s chromosomes have telocentric centromeres.

A

False - humans have none.

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6
Q

Where is an acrocentric centromere placed?

A

Very close to the top of the centromere.

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7
Q

What happens in prophase?

A

Spindle fibres appear and chromosomes condense

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8
Q

Describe prometaphase.

A

Spindle fibres attach to chromosomes, chromosomes condense further.

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9
Q

What happens in metaphase?

A

Chromosomes align down the equator.

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10
Q

What happens in anaphase?

A

Centromeres divide and sister chromatids move to opposite poles.

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11
Q

Describe telophase.

A

Nuclear membrane reforms, chromosomes decondense, spindle fibres disappear.

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12
Q

What occurs in cytokinesis?

A

Cytoplasm divides

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13
Q

True or false - sister chromatids have identical DNA and the same alleles?

A

True

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14
Q

Can homologous chromosomes have different alleles?

A

Yes, they often do.

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15
Q

What does meiosis produce?

A

Four non-identical cells with half of the chromosome content of the parental cell.

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16
Q

By which process are eggs and sperm produced?

A

Meiosis

17
Q

What makes meiosis I different from meiosis II?

A

In meiosis I, homologous pairs of chromosomes line up and separate. In meiosis II, chromosomes line up and chromatids separate.

18
Q

What are the consequences of meiosis?

A

Maintains constant chromosome number from generation to generation, and generates genetic diversity (random assortment of chromosomes and crossing over of genetic material).

19
Q

How long does spermatogenesis take?

A

Around 60 days.

20
Q

How many spermatids are produced from one spermatocyte?

A

4

21
Q

How long does oogenesis take?

A

12-50 years

22
Q

How many mature ova are produced from one primary oocyte?

A

One, and three polar bodies.

23
Q

What is nondisjunction?

A

When both copies of the chromosome are pulled to one pole instead of splitting.

24
Q

In what stage of the cell cycle does nondisjunction occur?

A

Anaphase

25
Q

What is a “metaphase spread”?

A

A technique where stained metaphase chromosomes are spread over a glass slide for analysis.

26
Q

What does this karyotype show? 46,XX

A

Female with no genetic conditions

27
Q

What does this karyotype show? 47,XY,+21

A

Male with trisomy 21 (Downs syndrome)

28
Q

What is aneuploidy?

A

Having the wrong number of chromosomes

29
Q

What is mosaicism?

A

Presence of two or more cell lines in an individual, can be throughout the body or tissue limited.