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Semester 1 - MCBG > 9. Mitosis And Meiosis > Flashcards

9. Mitosis And Meiosis Flashcards

1
Q

What are the names of the long and short arms of each chromatid

A

p (short) arm

q (long) arm

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2
Q

What are telomeres?

A

Telomeres are repeated sequences (TTAGGG) at each end of chromosome/chromatid

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3
Q

What are centromeres?

A

Centromere links the sister chromatids and consists of repetitive sequences

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4
Q

What are the names of the 4 types of chromosomes and where is the centromere found on each?

A

Metacentric- centre
Submetacentric - just above the centre
Acrocentric - even higher
Telocentric - right at the top

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5
Q

Which of the 4 types of chromosomes is not found in human?

A

Telocentric

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6
Q

How are chromosomes grouped?

A

Chromosomes
are grouped
according to size
and shape

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7
Q

What does mitosis produce?

A

production of two identical daughter cells

with same chromosome content as parental cell

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8
Q

In which cells do mitosis occur?

A

somatic cells

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9
Q

Why is mitosis important?

A
  1. For growth

2. for repair

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10
Q

In which 4 tissues is mitosis growth especially necessary?

A

epidermis, mucosae, bone marrow, spermatogonia

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11
Q

What are the 5 stages of mitosis?

A 
Prophase 
Prometaphase
Metaphase
Anaphase
Telophase
(Cytokinesis)
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12
Q

What happens in prophase?

A
  1. Breakdown of nuclear membrane
  2. Spindle fibres appear
  3. Chromosomes condense
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13
Q

What happens in prometaphase?

A
  1. Spindle fibres attach to centromeres of chromosomes

2. Chromosomes condense

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14
Q

What happens in metaphase?

A

Chromosomes align at the metaphase plane(centre of the cell)

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15
Q

What is kinetochore?

A

Complex of proteins that bind to the centromere

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16
Q

What happens in anaphase?

A
  1. Centromeres divide

2. Sister chromatids move to opposite poles

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17
Q

What happens in telophase?

A
  1. Nuclear membrane reforms
  2. Chromosomes decondense
  3. Spindle fibres disappear
18
Q

What happens in cytokinesis?

A
  1. Cytoplasm divides

2. Parent cell becomes two daughter cells with identical genetic information

19
Q

What are homologous chromosomes?

A

Chromosomes that have the same DNA sequence, same genes but have different alleles

20
Q

How are sister chromatids and non sister chromatids different?

A

• sister chromatids have identical DNA,
the same alleles
• non-sister chromatids have the same
genes, but maybe different alleles

21
Q

Describe meiosis

A

• special cell division for germ line cells
• production of four non-identical cells
(with half chromosome content of parental cell)
• one round of replication followed by two rounds of division (meiosis I and II)
• diploid (2n) reduced to haploid (n)
• production of eggs and sperm

22
Q

What happens in prophase 1 of meiosis ?

A
  1. Breakdown of Nuclear membrane
  2. Homologous chromosomes pair up
  3. CROSSING OVER occurs
23
Q

What happens during crossing over?

A

A bivalent forms and genes are swapped between two non sister chromatids at the chiasmata

24
Q

What happens in metaphase 1?

A

Homologous chromosomes line up at the metaphase plane

25
Q

What happens in anaphase 1

A

Homologous chromosomes separate

26
Q

What does meiosis 1 produce?

A

2 non identical daughter cells with diploid number

27
Q

What happens in metaphase 2?

A

Chromosomes line up at the metaphase plane

28
Q

What happens in anaphase 2?

A

Sister chromatids separate

29
Q

Wh is meiosis necessary?

A

• maintaining constant chromosome
number of from generation to generation

• generation of genetic diversity

  1. random assortment of chromosomes
  2. crossing over of genetic material
30
Q

What is spermatogenesis

A

Cell division to produce male gametes

31
Q

Describe spermatogenesis

A

A spermatogonium receives a signal to go through meiosis and becomes a primary spermatocyte which undergoes meiosis to produce 4 spermatic which mature into mature sperm

32
Q

What is oogenesis?

A

Cell division to produce female gametes

33
Q

Describe oogenesis

A

Oogonium receive signal to undergo meiosis and becomes a primary oocyte which divide by mitosis to form a mature ovum and 3 polar bodies

34
Q

What is anaphase lag?

A

delayed movement of a chromosome or chromatid during anaphase resulting in loss of the genetic material from inclusion into either daughter nucleus; Can occur during meiosis or mitosis.

35
Q

How many chromosomes does every human somatic cell contain in G2, just before mitosis?

A

46 - after DNA replication so chromosomes are 46 but DNA molecules are 92 and chromatids and 92

36
Q

Why is it that the nucleolus is present in the nucleus during interphase, but absent during
most of mitosis?

A

The nucleolus makes ribosomal subunit using rRNA which is needed to make proteins during interphase.However Protein production is not required
during mitosis so it disappears to allow
chromosomes to leave the nucleus
to undergo mitosis

37
Q

What is the function of the SRY gene?

A

They

determine the sex of a person

38
Q

What is aneuploidy?

A

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46

39
Q

Why does aneuploidy of the sex chromosomes have fewer adverse effects than aneuploidy
of autosomes.

A

This is because for females I X chromosome is inactivated to have the same amount of
genes (genetic
balances) as the XY
chromosomes.
The Y chromosomes don’t have
a lot of genes like the X as it’s mainly involved in
sex determination. If someone is XXY the
X will be inactivated so not a big problem

40
Q

What would be the consequence of anaphase lag in mitosis?

A

causes cell death or mutations

that could become cancerous due to loss ofchromosome

41
Q

What would be the consequence of anaphase lag in meiosis?

A

the loss of chromosomes would cause non functional
gametes
to be produced

42
Q

What is stage G0 of cell cycle? Why does it exist?

A

A separate stage outside the cell cycle where the cell is no longer dividing or preparing to divide.

Could be a temporary rest for cells where not much growth is needed and hen the correct signal is received, can reenter the cell cycle.

Could be a permeant rest where the cell will o longer divide

Semester 1 - MCBG (18 decks)

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