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Biol 207 > Topic 1: Chromosomes and Cellular Reproduction > Flashcards

Topic 1: Chromosomes and Cellular Reproduction Flashcards

1
Q

What is the n-value

A

The number of chromosomes of a cell

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2
Q

What is the c-value

A

Amount of DNA in an individual cell

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3
Q

Diploid vs haploid cells?

A

Diploid = cells that carry two sets of genetic information (two chromosomes)
Haploid = cells that carry one set of genetic information

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4
Q

n vs 2n

A

n= haploid
2n= diploid

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5
Q

What is polyploid

A

4n, 6n (# chromosomes)
Found in plants

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6
Q

In diploid cells, chromosomes occur in…

A

homologous pairs

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7
Q

Two kinds of homologous pairs

A

Similar but not identical (same genes in same order, different alleles of those genes)

Sister chromatids (identical alleles)

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8
Q

Two ways of measuring the amount of DNA within a haploid nucleus

A

Picograms, base pairs

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9
Q

Base pairs are measured in…

A

kb = kilo base = 100
Mb = mega = 1 million
Gb = giga = 1 billion

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10
Q

Number of chromosomes in a human

A

2n = 46

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11
Q

Number of genes in a human, genome size

A

21k genes
3 Gb genome

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12
Q

What is the c-value paradox

A

The number of genes does not indicate complexity, genome size, number of chromosomes, etc

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13
Q

Types of non-gene DNA?

A

Repetitive DNA
Centromeres
Telomeres

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14
Q

Two types of repetitive DNA, describe them

A

Moderately repetitive (150-300 bps long, found in many places in the genome, transposons)

Highly repetitive (<10 bps long, microsats)

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15
Q

What are centromeres

A

constricted region of chromosome where spindle fibers attach
Moderately repetitive DNA, tandemly repeating

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16
Q

What are telomeres

A

6 bp repeats, tandemly repeating
Repetitive sequence at the end of linear chromosomes

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17
Q

What is the role of telomeres

A

Solves end replication problem
Provide stability

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18
Q

The end of the chromosome that is overhanging (longer) is the

A

G-rich strand

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19
Q

What is the T-loop

A

G-rich strand folds over and pairs with a short stretch of DNA

20
Q

What organisms are T-loops found in, what are their role?

A

In mammals, provide stability to the end of the chromosome

21
Q

What are the phases of interphase, describe them

A

G1 = cell growth/development; G1/S checkpoint
S = synthesis phase (of DNA)
G2 = prepare cell for mitosis (division); G2/M checkpoint

22
Q

What is the M phase?

A

Mitotic phase (nuclear and cell division)

23
Q

What are the major checkpoints of mitosis, what do they look for?

A

G1/S = external conditions/DNA damage
G2/M = prevent entering into mitosis if DNA is damaged
spindle assembly = all chromosomes
properly attached to spindle apparatus

24
Q

Five phases of mitosis, describe them.

A

Prophase = chromosomes start to condense, centrosomes start to find each other

Prometaphase = disintegration of nuclear envelope

Metaphase = chromosomes line up on metaphase plate individually; spindle-assembly checkpoint

Anaphase = sister chromatids separate

Telophase = chromosomes arrive at spindle poles, nuclear envelope re-forms

25
Q

Slide 19**

A

Mitosis summary

26
Q

What are the genetic consequences of the cell cycle

A
  • produces two genetically identically cells
  • new cells contain full complete set of chromosome
  • each new cell contains half the cytoplasm of the parent cell
27
Q

Meiosis produces…

A

haploid gametes (2n -> n)

28
Q

Fertilization produces…

A

Fusion of two haploid cells (n -> 2n)

29
Q

Broad phases of meiosis

A

Interphase (same as mitosis; G1, S, G2)
Meiosis I (separation of homologous chromosomes)
Meiosis II (separation of sister chromatids)

30
Q

Describe meiosis 1, aka…

A

Reduction division
2n -> n
Metaphase plate homologous pairs line up
Different from mitosis due to change in ploidy

31
Q

Describe meiosis 2, aka…

A

Equational division
n -> n (no change in ploidy, similar to mitosis)

32
Q

Three steps of prophase 1 during meiosis 1

A

Synapsis: homologous pairs find each other, pair up
Tetrad: the chromosomes are now a tetrad
Crossing over: exchange of genetic material between homologous chromsomes

33
Q

What is the chiasmata

A

Forms between homologous chromosomes (links them) before crossing over; prepares for separation/reattachment

34
Q

What happens during metaphase 1 in meiosis 1

A

Tetrads line up on metaphase plate

35
Q

What happens during anaphase 1 in meiosis 1

A

Separation of homologous chromosomes (segregate independently)

36
Q

What is interkinesis

A

Stage between M1 and M2

37
Q

During mitosis anaphase, what does separase do? What happens after?

A

Cuts all the cohesins

Microtubules then pull sister chromatids apart

38
Q

What does shugoshin do

A

Protein that is added to cohesin to protect it from separase (only to cohesins near centromere)

39
Q

Stages of Meiosis 2

A

Prophase II, Metaphase II, Anaphase II, Telophase II

40
Q

Difference between meiosis II and mitosis

A

Similar, except meiosis 2 starts off with 2 haploid cells and we end up with 4 haploid cells

41
Q

What happens during metaphase 2 in meiosis 2

A

Individual chromosomes line up at metaphase plate

42
Q

What happens during anaphase 2 in meiosis 2

A

Separation of sister chromatids

43
Q

Products of meiosis 2

A

4 haploid cells (gametes)

44
Q

Consequences of meiosis on chromosome number

A
  • Reduced by half
  • Diploid to haploid
45
Q

Newly formed cells from meiosis are…

A

Genetically different from one another and from the parental cell

Biol 207 (22 decks)

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