meiosis quiz 9 Flashcards by Keagan Cress

In a multi-cellular organism, what type of cell would undergo meiosis?

Meiocytes, Oocytes, Spermatocytes

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What is ploidy?

The number of sets of chromosomes within a cell

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What is the difference between a diploid and haploid cell?

Haploid - one copy/set of each chromosome I (1n)
Diploid - two copies/sets of each chromosomes II (2n)

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What is a homologous pair of chromosomes?

A homologous pair of chromosomes is two chromosomes in a pair

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What are sister chromatids?

One of two identical halves that make up a chromosome

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How many strands of DNA are in a typical replicated chromosome? (G2 Phase)

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What are non-sister chromatids?

Non-sister chromatids are chromatids that are on opposite homologs in a homologous pair, they are not identical.

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What is a dyad?

A dyad is a pair of sister chromatids (homolog) X

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What is a tetrad?

A tetrad is two pairs of sister chromatids (homologous pairs) XX

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A diploid cell that will undergo meiosis has 4 chromosomes. Fill in the blanks referring to chromosome number, DNA amount, and ploidy.

G1: Chromosome # :
DNA amount :
Ploidy :
G2: Chromosome # :
DNA amount :
Ploidy :

G1: 4
1x
2n

G2: 4
2x
2n

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What is happening to the chromosomes in Prophase I of Meiosis?

Chromatin condenses
Nuclear membrane dissolves
Crossing over between non-sister chromatids
-> As chromatin condenses, homologous pairs of chromosomes pair up, finding one another and aligning. After crossing over, each homolog is now made of portions of the paternal and maternal chromosomes from the previous generations.

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Explain what “crossing over” refers to during prophase I of meiosis

The matching, pairing, alignment of homologous chromosomes and the cross of DNA between the non-sister chromatids

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What is happening during Mid-Meiotic Interphase of Meiosis? For just one of the cells:

Chromosome #:
DNA Amount:
Ploidy:

ASK CAHOON

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What is happening during Telophase II and Cytokinesis II of Meiosis? For one of the cells:
Chromosome #:
DNA Amount:
Ploidy:

HAPLOID 1n=2/1n=10

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What is a gamete?

a matured male or female haploid cell

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What is non-disjunction?

When chromosomes do not separate properly

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Since Meiosis is the source of _____ cells, incorrect chromosome separation during this process is the source of ______ that result from _____ or ____ chromosomes

sex; genetic disorders; extra; missing

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Since Meiosis is the source of _____ cells, incorrect chromosome separation during this process is the source of ______ that result from _____ or ____ chromosomes

sex; genetic disorders; extra; missing

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What is the correlation between non-disjunction and human maternal age? Why is there a correlation?

Chances of non-disjunction increase as age increases - ASK CAHOON, SOMETHING WITH THE CELLS STICKING TOGETHER?

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What is the most common outcome of aneuploidy - when a human zygote receives an extra chromosome (trisomy) or one less chromosome (monosomy?)

Trisomy

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In terms of aneuploidy, what are Patau’s, Edward’s and Down’s syndromes?

Trisomy 13, Trisomy 18, and Trisomy 21

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Why can an extra X chromosome tolerated during human development?

Cells have the ability to shut down extra X-chromosomes in a process called X-inactivation

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In terms of aneuploidy, what are XXX, Klinefelters, XYY, and Turners syndromes?

XXX - extra X for females
Klinefelters - extra X for males
XYY - extra Y chromosome for males

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Define Aneuploidy

abnormal amount of chromosomes

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Define monoploidy

missing chromosome (1n-1)

On a recent expedition to Monster Island, you collect tissue samples from gigantic Godzilla-like creatures. Upon examining their chromosomes, you discover they are diploid with 12 homologous pairs. (2n=24). Draw out the ploidy and total # of chromosomes you would expect in G1, Metaphase I, Metaphase II, in a sperm cell, and in a skin cell

PLOIDY STAYS THE SAME FROM G1 TO G2. DNA AMOUNT IS DOUBLED 2n - > 2n -> 1n + 1n -> 1n + 1n + 1n + 1n

Bonus Q: How did you get the tissue samples from the giant godzilla-like creatures?

Biopsy

What stage of meiosis would this event occur? Individual dyad chromosomes align along a single plane

Metaphase II

What stage of meiosis would this event occur? Homologous pairs of chromosomes (tetrads) separate into dyads

Anaphase I

What stage of meiosis would this event occur? Dyads separate into individual chromosomes

Anaphase II

What stage of meiosis would this event occur? Homologous pairs of chromosomes condense

Prophase I

What stage of meiosis would this event occur? Homologous pairs of chromosomes cross over

Prophase I

What stage of meiosis would this event occur? Dyad chromosomes (not homologous pairs) condense from chromatin

Prophase II

Horses are diploid and have 64 chromosomes. Fill in the chart below with the correct chromosome numbers and ploidy for a horse meiocyte G1 : # of chromosomes = Ploidy = Mid-meiotic interphase: # of chromosomes = Ploidy = Gamete: # of chromosomes = Ploidy =

G1 - 2n=64 MidMeiotic - 2n=64 Gamete = 1n=32

Describe the difference between sister and non-sister chromatids

Sister chromatids identical replications of themselves on the same homologous chromosome, while non-sister chromatids are on the opposite homologous chromosome in a homologous pair, non identical

Define primary and secondary non-disjunction in meiosis

ASK CAHOON

Turkeys are diploid and have 80 chromosomes. What is the DNA content, chromosome number, ploidy, dyad, and tetrad content of a turkey spermatocyte (gamete producing cell) at prophase I of meiosis? Assume the G1 phase has 1X DNA. DNA = 1 Chromosome # = 80 Ploidy = 2 Dyads (homologous chromosome) = 80 Tetrads (homologous pair) = 40 Prophase II (one of the two cells formed from meiosis one)? DNA = 2 Chromosome # = 40 Ploidy = 1 Dyads = 40 Tetrads = 20 Each of the turkey sperm cells at the end of meiosis? DNA = 2 Chromosome # = 40 Ploidy = 1 Dyads = 40 Tetrads = 20

ASK CAHOON AND CHECK YOUR ANSWER ON THIS. THE DINOSAUR ONE TOO.

Describe/list what happens to chromosomes (three events) during prophase I of meiosis

- Chromatin condenses - Nuclear membrane dissolves - Crossing over between non-sister chromatids

Aneuploid conditions involving the human "X" chromosome are tolerated at a much higher degree than any autosomal chromosome. Why?

X-inactivation by the cell

what type of reproduction is guided by meiosis?

sexual reproduction

What is the purpose of meiosis?

Divide genetic material in half to enable sexual reproduction - reduce ploidy by half

The number of chromosome "sets" in a cell is referred to as its...

Ploidy

What term is used to describe two chromatids on a single dyad?

Sister chromatids

What term is used to denote the two chromatids on different dyads in a homologous pair

Non-sister chromatids

What distinguishes Meiotic Prophase I from Mitotic Prophase?

Crossing over between homologous chromosomes

What is separated during Meiotic Anaphase I

Tetrads/ could also be dyads - dependant on how q is asked

At the end of Meiosis I, what is the ploidy of the 2 products?

Haploid - 1n

What is separated during Meiotic Anaphase II?

Sister chromatids

At the end of meiosis II, what is the ploidy of the two products?

Recite the entire Meiosis process, in order

G1,S, G2, Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, Mid-Meiotic Interphase, Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis

What happens during Prophase I? Draw Prophase I.

- Chromatin condenses - nuclear membrane dissolves - crossing over between non-sister chromatids - crossing over

What happens during Metaphase I? Draw Metaphase I.

- Tetrads align along a plane, not single file

What happens during Anaphase I? Draw Anaphase I.

- Tetrads separate, dyads migrate to each pole

What happens during Telophase? Draw Telophase.

- Migration complete - Nuclear membrane forms - Tetrads de-condense

What happens during mid-meiotic interphase?

- Cells undergo a semi G1-G2 phase but do not replicate DNA

What happens in Prophase II? Draw Prophase II.

- Nuclear membrane dissolves - Chromosomes/Dyads condense

What happens in Metaphase II? Draw Metaphase II.

- Dyads align along a central plane

What happens during Anaphase II? Draw Anaphase II.

- Dyads pull apart and chromosomes migrate to poles

What happens during Telophase II?

- Migraation finishes - Nuclear Membrane reforms - Chromosomes de-condense into chromatin

Ploidy is reduced from ____ to ____ in Meiosis I

2n; 1n

Ploidy _____ throughout Meiosis II

Remains the same; unchanged

Klinefelters syndrome

Human sex chromosome trisomy; XXY

An abnormal number of chromosomes

Aneuploidy

Down's syndrome

Human trisomy 21

One extra chromosome

Trisomy

Turners syndrome

Human sex chromosome monosomy

Edwards syndrome

Human trisomy 18

One missing chromosome

Monosomy

Pataus syndrome

Human trisomy 13

What does nondisjunction of a dyad result in?

Abnormal number of chromosomes in two of the four gametes

What does non-disjunction of a homologous pair of chromosomes result in?

An abnormal number of chromosomes in all four gametes

In a multi-cellular organism, what cell type would undergo meiosis?

Gametocytes and meiocytes

What types of cells are produced by meiosis?

Gametes

The number of chromosome "sets" in a cell is referred to as its

Ploidy

If a species has two sets of chromosomes in every cell (one maternal and one paternal) we refer to this as...

Diploid

If a cell is 2n before beginning the process of meiosis, what is its ploidy at the end of meiosis II?

What distinguishes meiotic prophase I from mitotic prophase and meiotic prophase II?

Homologous pairs of chromosomes align and cross-over in meiotic prophase I but not in meiotic prophase II or mitotic prophase

Why do some cells undergo meiosis?

To make haploid cells that can fuse with another haploid cell to facilitate sexual reproduction

If a cell is 2n before beginning the process of meiosis, what is its ploidy at the end of meiosis I?

What do we call the chromosomes found on the two different dyads of a homologous pair of chromosomes

non-sister chromatids

meiosis quiz 9 Flashcards

(80 cards)