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Alia - Biology > Lecture 9-Cell Cycle > Flashcards

Lecture 9-Cell Cycle Flashcards

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1
Q

What are autosomes?

A

Non-sex chromosomes ~22 pairs

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2
Q

What are histones?

A

highly alkaline proteins found in eukaryotic cell nuclei

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3
Q

What do histones do?

A

Package + order the DNA into structural units = nucleosomes

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4
Q

Somatic cells

A

all the cells of the body except sperm and egg cells

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5
Q

Prokaryotic cells

A

no nucleus / any other membrane bound organelles

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6
Q

Eukaryotic cells

A

contain membrane bound organelles and nucleus

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7
Q

Mitosis

A

division resulting in 2 identical daughter cells

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8
Q

Meiosis

A

division results in 4 sex cells

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9
Q

Cytokinesis

A

cytoplasmic division

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10
Q

Apoptosis

A

programmed cell death : internal signalling

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11
Q

Necrosis

A

death of most/all cells in an organ/tissue ,because of disease, injury or failed blood supply : external factors

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12
Q

What is the cell cycle?

A

The orderly sequence of events required for duplication in eukaryotic cells for 2 genetically identical daughter cells

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13
Q

What are the 2 divisions in a cell cycle?

A

nuclear (mitosis) + cytoplasmic (cytokinesis)

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14
Q

How is the finite number of divisions controlled by a cell?

A

Activation of suicide genes

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15
Q

How many cells die each day due to apoptosis?

A

50-70 billion cells

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16
Q

Atrophy?

A

Tissue waste away ,due to degeneration of cells

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17
Q

Dysplasia?

A

presence of additional cells of an abnormal type within a tissue, which may signify a stage preceding the development of cancer

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18
Q

Interphase?

A

The phase between 2 successive mitotic divisons

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19
Q

What happens during interphase?

A

The cell grows + prepares for division

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20
Q

What are the phases of interphase?

A

G1, S + G2

pre-synthesis, synthesis, post-synthesis

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21
Q

What are the important checkpoints in interphase?

A

G1 + G2

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22
Q

What is a cell in interphase in G0 doing?

A

Not dividing / preparing to divide

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23
Q

Give an example of a cell in G0?

A

Neurones

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24
Q

What formation happens in interphase?

A

Centriole formation + mitotic sindle formation

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25
Q

Cells can’t pas G1 phase without?

A

Growth factors

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26
Q

How long does G1 last for?

A

8-10 h /24 h

27
Q

What are the markers of G1?

A
  • High metabolism rate
  • Protein synthesis
  • Vigorous growth
  • Most organelles duplicated
  • Centrosome replication begins
28
Q

What is the initiation stage in interphase?

A

G1

29
Q

How long does the S phase last for?

A

8 h

30
Q

What happens during the S phase?

A

DNA replicates

31
Q

What must happen during the S phase to ensure the prevention of cell death / diseases?

A

Precise + accurate DNA replication (prevent genetic abnormalities)

32
Q

Describe the process of DNA replication?

A

1) Catalysed by DNA polymerase
2) Energy from ATP hydrolysis
3) DNA uncoiling , because of breaking of H bonds between nitrogenous bases
4) Each new strand contains complementary base pairs to template strand
5) H bonds form = 2 daughter molecules

33
Q

What is specific about DNA helicase?

A

Untwists helix at specific locations = replication origins

-This forms a Y shape = replication fork

34
Q

How long does the G2 phase last for?

A

4h

35
Q

What happens during the G2 phase?

A

Enzyme + protein synthesis
+
replication of centrioles fully completed ( form the spindle apparatus)

36
Q

What is the mitotic phase characterised by?

A

Karyokinesis + cytokinesis

37
Q

What is karyokinesis?

A

Division of the nucleus

38
Q

What is cytokinesis?

A

Division of the cytoplasm

39
Q

How long does mitosis occur?

A

<1 h

40
Q

What is the centrosome?

A

The main microtubule organising centre + regulator of cell-cycle progression

41
Q

Kinetochore?

A

the protein structure on chromatids where the spindle fibres attach to pull the chromatids apart

42
Q

Centromere?

A

Part of the chromosome that links sister chromatids

-Spindle fibres attach here via the kinetochore

43
Q

What are chromatids?

A

Thread-like strands that containDNA helic

44
Q

What is chromatin?

A

Complex of DNA + proteins that forms chromosomes

45
Q

Prophase?

A

The chromatin coils + condenses –> chromosomes
(Stops tangling )
- Each chromosome = 2 chromatids
-Kinetochore = needed 4 spindle attachment
- Growing spindle pushed centrosomes to opposite poles
-Nucleoli disappears ( more space )
- Cytoskeletal microtubules disassemble
-Centriole pairs separate + move to opposite ends (growth of new microtubules forming mitotic spindle)

46
Q

Prometaphase?

A

Nuclear envelope = breaks

Microtubules connect the kinetochores –> centrosomes

47
Q

Metaphase?

A

The microtubules line-up the chromosomes at the cell’s equator
-Chromosomes = maximum coiling

48
Q

Anaphase?

A

The chromatids separate via kinetochore + the new chromosomes = daughter chromosomes (each formed from 1 chromatid) move toward the poles (because of interactions between the kinetochore + microtubules)

49
Q

What is the longest sub-phase of mitosis?

A

Prophase

50
Q

Telophase?

A

BEGINS AFTER THE CHROMOSOMAL MOVEMENTS STOPS
The separating chromosomes reach the poles
-The nuclear envelope reforms around chromatin mass
-Chromosomes uncoil + transform –> chromatin
-Nucleoli reappear + mitotic spindle disappears

51
Q

What marks the end of Karyokinesis?

A

Telophase

52
Q

When does Cytokinesis begin?

A

At the end of anaphase + continues through telophase + beyonf

53
Q

Cytokinesis?

A 
Cell organelles (ribosomes + mitochondria) evenly distribute around 2 daughter nuclei
-Cytoplasm --> CLEAVAGE FURROW = deepens finally separating 2 daughter cells (each with the same complement of chromosomes as the parent cell)
54
Q

What regulates the initiation of cell-growth?

A

Cyclin-dependent kinases

55
Q 
Name the cyclin for each phase:
G1
S
G2
M
A 
G1 = cyclin D ,CDK4
G1-S = cyclin E,CDK2
S = cyclin A,CDK2
G2 = cyclin A,CDK1
M = cyclin B,CDK1
56
Q

What are cell cycle checkpoints?

A

The control mechanisms that ensure the reliability of cell division
-Asses DNA damage

57
Q

What happens when a cell cycle checkpoint finds DNA damage?

A

Uses a signal mechanism
-Stall cell cycle until repair
OR
-Target cell destruction via apoptosis

58
Q

What is the restriction point and where is it found?

A

Late in G1 phase

- Cells that should cease dividing exit the cell cycle and enter G0

59
Q

What cells continually divide ?

A

Haematopoietic stem cells

Gut epithelial cells

60
Q

How do you overcome the G0 checkpoint?

A

The growth-factor induced expression of cyclin D proteins

61
Q

What is the mitotic spindle checkpoint and when does it occur?

A

End of G2 phase

Occurs in metaphase when all the chromosomes should have aligned at the mitotic plate + be under bipolar tension

62
Q

Describe the markers of cancer development?

A 
Genetic mutation 
Hyperplasia
Dysplasia
In situ cancer
Invasive cancer
63
Q

Describe how cancer devleops?

A

Mutation inactivates tumour suppressor genes
Cells proliferate
Mutation inactivates DNA repair gene
Mutation of proto-oncogene —-> oncogene
Mutation inactivates several other tumour suppressor genes
Cancer

64
Q

When is anaphase blocked?
When is DNA damage checkpoint entrance into S blocked?
When is entrance into M blocked?

A
  • Chromatids not properly assembled on mitotic spindle
  • Damaged genome
  • Uncompleted DNA replication

Alia - Biology (10 decks)

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