2 - Mitosis And Meiosis Flashcards

1
Q

What is the structure of a chromosome with two DNA molecules?

A
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2
Q

When looking at a eukaryotic cell under the microscope, why might there be no nuclear envelope?

A

Cell may be undergoing mitosis or meiosis

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3
Q

What are the four types of centromere?

A
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4
Q

How are chromosomes classified and what are X and why?

A
  • Based on their size and centromere type
  • Go in descending size from 1-22
  • Grouped A-G
  • X is C and Y is G
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5
Q

How does DNA polymerase proof-read?

A
  • Contains a restriction endonuclease
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6
Q

What is the proccess and outcome of mitosis?

A

Outcome: 2 identical diploid daughter cells, somatic cell replication for growth and repair

Prophase: nuclear envelope disintegrates, chromosomes condense, centrioles move to opp ends

Prometaphase: spindle attach by kinetochore

Metaphase: chromosomes line up randomly on the equator

Anaphase: spindles contract, centromere splits, sister chromatids go to opposite poles of cell and they appear v-shaped

Telophase: two groups of chromosomes, new nuclear envelope surrounds each group. chromosomes uncondense.

Cytokenesis: from cleavage furrow

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7
Q

Where are chromosomes during interphase?

A

In their own territories in the nucleus as chromatin

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8
Q

What is a metaphase spread?

A
  • Where chromosomes are analysed when the cell is arrested during metaphase as the chromosomes are highly condensed
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9
Q

What are non-sister chromatids and what do they have in common?

A

Chromsomes in the same tetrad

Both have same genes but different alleles

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10
Q

What is the outcome of meiosis and why is it carried out?

A
  • 4 haploid non-identical daughter cells
  • Used to create genetic diversity and maintain the chromosome number throughout generations
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11
Q

What is the process of meiosis?

A
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12
Q

What is crossing over?

A
  • Homologous chromosomes in a bivalent
  • Non sister chromatids form chiasmata and swap genetic information
  • Essential, if didn’t occur may lead to both chromosomes ending up in one cell
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13
Q

What is a karyotype?

A
  • Can physically see all the bands and chromosomes

OR

  • Chromosome number:

47,XY,+21

(no spaces, just commas)

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14
Q

Why is the ova larger than the sperm?

A

Ova contains all the organelles and cytoplasm for cell growth but sperm just needs genetic material

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15
Q

What generates genetic diversity?

A
  • Independent assortment
  • Crossing over
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16
Q

What is the importance of G0?

A
  • Stops cells over replicating
  • If they recieve a signal, they can reenter the cell cycle for tissue repair

(neurones never can, liver can)

17
Q

How do autosomes pair up in meiosis?

A
  • Contain similar DNA sequences so they pair up
18
Q

What is anaphase lag?

A
  • Where chromosomes dont attach to the spindle fibre or they get left behind in the cytoplasm
  • DNA lost as degraded in cytoplasm
  • Aneuploidy
19
Q

Compare and contrast mitosis and meiosis?

A

Mitosis

  • One division , one replication
  • 2 identical diploid cells
  • Has prometaphase

Meiosis:

  • Two divisions, one replication
  • 4 haploid non-identical daughter cells
  • Crossing over
  • Independent assortment
  • Homologous chromosomes pair up
20
Q

What is the nucleolus and why isn’t it visible during mitosis?

A
  • Contains DNA from five chromosomes. Used to produce ribosomal RNA
  • During mitosis all DNA is condensed into chromosomes and they are on the equator of the cell
21
Q

What is the process of oogenesis?

A
22
Q

What is the process of spermogenesis?

A
23
Q

What is the SRY gene?

A

The gene that codes for male development

If crossing over occurs in a male, and SRY passed to X chromosome, daughter can inherit this and be intersex

  • She has XX but no female development as presence of SRY gene
  • Intersex children