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BIOL 130 > Module 11 (DNA Replication and Cell Division) > Flashcards

Module 11 (DNA Replication and Cell Division) Flashcards

1
Q

Why does cell division occur?

A

Cell growth
Cell replacement
Cell healing
Cell reproduction

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2
Q

How can a cell make more cells?

A

Using the process known as cell division

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3
Q

Requirements of cell division

A
  • The parent cell must be big enough to divide (so the daughter cells get enough cytoplasmic components)
  • The two daughter cells must each receive all of the genetic material from the parent cell
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4
Q

How do prokaryotic cells divide?

A

Using binary fission

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5
Q

Steps of Binary Fission

A

Protein bind circular DNA to inner membrane
DNA replication travels bidirectionally
The new circular DNA is also attached to the inner membrane
Cell elongates, and starts to pinch at middle of cell
New cell membrane and cell wall separates the daughter cells

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6
Q

Genome

A

Genetic material of an organism

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7
Q

Mitochondrial genome

A

Maternally inherited

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8
Q

Is there a correlation between genome size and organismal complexity?

A

No! There is no correlation. An amoeba has 670000kb, but a human has 3100kb

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9
Q

Nucleoid

A

Loops of circular DNA, coiled around itself, bound together by proteins

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10
Q

Chromatin

A

Nucleosomes packaged together, forms a strand (about 30nm in diameter)

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11
Q

Nucleosomes

A

DNA is wrapped around histone proteins twice (10nm in diameter)

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12
Q

Coiled chromatin fiber

A

Chromatin fiber is further coiled (300nm)

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13
Q

Coiled coil

A

The coiled chromatin fiber is coiled further (700nm)

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14
Q

Chromatid

A

Only visible in cells that are about to divide, made from coiled coils (1400nm)

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15
Q

Stem cells

A

Undifferentiated cell that can undergo unlimited amounts of cell division and differentiate into any of the specialized cells (found in bone marrow when talking about blood cells)

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16
Q

Somatic cells

A

Nonrepoductive cell, most common type of cell (normal)

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17
Q

Germ cells

A

Reproductive cells that produce gametes (eggs or sperm)

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18
Q

The time when the parent cell divides into two daughter cells

A

M phase

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19
Q

How does cell division occur in eukaryotes?

A

Through the cell cycle

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20
Q

The time between two successive M phases is known as…

A

Interphase

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21
Q

Cytokinesis

A

The division of the cytoplasm into two daughter cells

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22
Q

Mitosis

A

Separation of replicated chromosomes

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23
Q

How long does interphase usually last between two M phases?

A

Around 10-14 hours

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24
Q

Cell’s preparations before division

A

DNA replication in nucleus
Increasing the size of the cell

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25
Q

G1 phase

A

First stage in interphase
- increase cell size and protein content
- 1st gap phase
- Synthesis and activation of regulatory proteins

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26
Q

S phase

A

“Synthesis” phase, second phase in interphase
- DNA replication

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27
Q

G2 phase

A

Third phase of interphase
- Second “gap” phase
- Preparation for M phase

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28
Q

G0 phase

A

Separate from G1, no active preparation for cell division
- cells that do not divide (liver cells- hepatocytes)

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29
Q

What does it mean by “DNA replication is semiconservative”?

A

Each strand of parental DNA acts as a template strand for the synthesis of a daughter strand

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30
Q

One strand of DNA is ________, one strand is _________

A

One strand is old parental, one strand is newly synthesized

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31
Q

Replication Fork

A

The place where the two strands of DNA split from each other during replication

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32
Q

Helicase

A

Unwinds parental DNA at replication fork

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33
Q

Single-strand binding protein

A

Holds the single stranded regions of the parental strands to prevent them from coming back together.

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34
Q

Topoisomerase

A

Relieves the stress of unwinding the DNA, works upstream the replication fork

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35
Q

DNA Polymerase

A

Adds bases to nucleotide strand, requires four deoxyribonucleotides (dATP, dGTP, dCTP, dTTP)
- Only synthesize DNA in 5’-3’
- Can usually correct mistakes as it goes
- Needs an RNA primer
- Also removes RNA primers and replaces with DNA bases

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36
Q

RNA primase

A

Creates the RNA primer with the 3’ OH group that allows the DNA polymerase to start to synthesize the DNA

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37
Q

What is the purpose of the 3’OH group on the RNA primer?

A

It attacks the phosphate bond of the incoming nucleotide to initiate the synthesis

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38
Q

Leading strand

A

The strand that grows continuously toward the replication fork

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39
Q

Lagging strand

A

The strand that grows away from the replication fork, synthesized in segments

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40
Q

Okazaki fragments

A

The synthesized pieces of the lagging strand that are disconnected from each other

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41
Q

DNA ligase

A

Okazaki fragments are joined together after RNA primers have been replaced with DNA nucleotides

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42
Q

Trombone Model

A

As the DNA is being unwound, one strand is looped

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43
Q

How are DNA replication errors caught?

A
  • DNA polymerase can detect mispairing of hydrogen bonding
  • Removes incorrect nucleotide, and inserts correct one
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44
Q

Replication of circular DNA

A

Happens in most bacteria
- Single origin of replication, replication goes in both directions until they meet on the opposite side and fuse

45
Q

Leading and lagging in circular DNA

A

Each replication fork has a leading strand and a lagging strand (two replication forks)

46
Q

Linear DNA origins of replication

A

Eukaryotes have multiple origins of replication, multiple replication forks, and proceeds bidirectionally, when two replication bubbles meet, DNA ligase seals the gap in fragments

47
Q

At the end of Linear DNA…

A

On the lagging strand, the primer is removed and leaves a section of template of DNA unreplicated, every time DNA is replicated one strand is shortened

48
Q

Telomeres

A

End of chromosomes with repeated sequence, repeats thousands and thousands of times

49
Q

Telomerase

A

Extends the ends of the chromosome by replacing missing nucleotides
- Ribonucleoprotein -> protein RNA complex
- Carries its own primer (template RNA)
- Reverse transcriptase activity

50
Q

What types of cells is telomerase active

A

Stem cells
Germ cells (sex cells)

51
Q

Hayflick limit

A

The maximum number of times that a cell can replicate before the telomeres become too short
About 50 times

52
Q

Haploid

A

A cell with one copy of each chromosome

53
Q

Diploid

A

A cell with two copies of each chromosome

54
Q

Sister chromatids

A

Identical copies of chromosomes after DNA replication, held together at the centromere

55
Q

Karyotype

A

A visual representation of one’s chromosomes

56
Q

Mitosis

A

For somatic cells to duplicate

57
Q

Stages of Mitosis

A

Prophase, Prometaphase, Metaphase, Anaphase, Telophase

58
Q

Prophase

A

Chromosomes condense, cell assembles mitotic spindle, centrosomes duplicate and migrate to opposite poles

59
Q

Prometaphase

A

Nuclear membrane breaks down, microtubules of grow and shrink looking for chromosomes (attach to them)

60
Q

Kinetochores

A

Two protein complexes that a centromere is associated with, one on each side of centromere, site of attachment for microtubule

61
Q

Metaphase

A

Mitotic spindle lengthens and shortens pushing chromosomes toward center of the cell

62
Q

Metaphase plate

A

The plane approximately half way between the two poles of the spindle where the chromosomes line up

63
Q

Mitotic spindle

A

Made of microtubules, pull chromosomes apart

64
Q

Anaphase

A

Centromere divides and kinetochore microtubules shorten, pulls chromatids apart, one to each pole

65
Q

Telophase

A

Complete set of chromosomes arrives at spindle pole, microtubules of mitotic spindle break down, nuclear envelopes form around each chromosome set, chromosomes decondense

66
Q

Cytokinesis in animal cells

A

The division of the parent cell into two daughter cells
- Ring of actin filaments form around inner face of cell membrane, which contracts and pinches the cytoplasm, divides it

67
Q

Contractile ring

A

Forms at the equator of the cell, ring of actin filaments, contracts to pinch the cytoplasm of the cell

68
Q

Cytokinesis in plant cells

A

Forms phragmoplast in middle of cell during telophase, guide vesicles with cell-wall components to middle of the cell, vesicles fuse to form a new cell wall in the middle (late Anaphase and Telophase), which then fuses with original cell wall

69
Q

Phragmoplast

A

Overlapping microtubules that guide vesicles containing cell-wall components to the middle of the cell in plant cells

70
Q

Cell plate

A

The new cell wall formed by fused vesicles in the middle of the parent plant cell

71
Q

Meiosis

A

Produce daughter cells with half as many chromosomes as the parental cell, source of variability, one round of DNA synthesis, two rounds of cell division

72
Q

By the end of meiosis I

A

The homologous chromosomes separate

73
Q

By the end of meiosis II

A

The sister chromatids separate

74
Q

Meiosis I, Prophase I

A

Homologous chromosomes pair with each other, chiasma occurs

75
Q

Synapsis

A

When homologous chromosomes pair with each other

76
Q

Bivalent

A

Two pairs of sister chromatids (tetrad)

77
Q

Chiasma

A

Crossing over of DNA segments, exchanging genetic information, random, also helps hold bivalents together

78
Q

Meiosis I, Prometaphase I

A

Spindles attach to kinetochores on chromosomes

79
Q

Meiosis I

A

Results in homologous chromosomes separated, haploid cells, reductional division (# of chromosomes are halved)

80
Q

Meiosis II

A

Sister chromatids separate, results in gametes, equational division, Cells in meiosis II have the same # of chromosomes at the beginning and the end

81
Q

Mitosis vs. Meiosis

A

Suggests that meiosis evolved from mitosis, common ancestor of eukaryotes

82
Q

Cytoplasmic division in female gametes

A

One cell with most of the cytoplasm, three polar bodies with only small amounts of cytoplasm, only the large one is yielded

83
Q

Oocyte

A

Female egg

84
Q

Cytoplasmic division in male gametes

A

Equal cytoplasmic division, most of cytolasm is eliminated

85
Q

Sperm meeting egg

A

Restores diploid state and increases genetic diversity

86
Q

Initiation of DNA repliaction

A

G1/S transition

87
Q

Initiation of mitosis

A

G2/M transition

88
Q

How are is the cell cycle controlled?

A

Cyclic activity of proteins and kinase

89
Q

What are the proteins and kinases that control the cell cycle?

A

Cyclins and cyclin-dependent kinases (CDK)

90
Q

Cyclins

A

Regulatory protein subunits of specific protein kinases

91
Q

CDKs

A

Kinases that phosphorylate other proteins whose actions are necessary for the cell cycle to progress (protein is active), only active when bound to cyclin
- Different types that act at different steps of the cell cycle

92
Q

Cyclin D and Cyclin E

A

Levels increase in G1 phase, activates transcription factors that lead to expression of DNA polymerase

93
Q

Cyclin A

A

Activates CDKs that initiate DNA synthesis during S phase

94
Q

Cyclin B

A

Increases during G2 phase, activate CDKs that initiate the breakdown of nuclear envelope, formation of mitotic spindle

95
Q

DNA damage checkpoint

A

Checks for damaged DNA before the S phase (for example, breaks in DNA strand)

96
Q

DNA replication checkpoint

A

Checks for unreplicated DNA at the end of G2

97
Q

Spindle assembly checkpoint

A

Checks that all chromosomes are attached to the spindle before the cell continues with mitosis

98
Q

If DNA is damaged by radiation

A

Activates a protein kinase that phosphorylates the p53 protein, which activates the transcription of some genes, one blocks the activity of the G1/S cyclin-CDK complex, freezes the cell at the G1/S transition, cell is able to repair damage

99
Q

p53 is often called…

A

The guardian of the genome

100
Q

Phosphorylated p53 also…

A

Stimulates the production of bax protein, represses transcription of Bcl-2 protein, shift the overall concentrations of of them, creating Bax-bax dimers, creating apoptosis

101
Q

Apoptosis

A

Increase of Bax-bax dimers causes programmed cell death

102
Q

Apoptosis in embryotic development

A

Hands initially look like a paddle until cells are killed, creating digits

103
Q

Uses of apoptosis

A

Maintenance of tissue size, elimiation of specific cells, elimination of genetically damaged cells

104
Q

Cancerous cells

A

Unable to undergo apoptosis, uncontrolled cell division

105
Q

Oncogenes

A

Cancer-causing genes first discovered in viruses

106
Q

Proto-oncogenes

A

Normal genes important in cell division that have the potential to mutate into oncogenes

107
Q

Tumour suppressor gene

A

Opposite of oncogenes, inhibit cell division, p53 protein is an example

108
Q

Metastasis

A

When cancer cells invade tissues

109
Q

Angiogenesis

A

The blood vessel formation caused by cancer cells

BIOL 130 (11 decks)

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