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Alia - Biology > Lecture 9-Cell Cycle > Flashcards

Lecture 9-Cell Cycle Flashcards

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
Cells can't pas G1 phase without?
Growth factors
26
How long does G1 last for?
8-10 h /24 h
27
What are the markers of G1?
- High metabolism rate - Protein synthesis - Vigorous growth - Most organelles duplicated - Centrosome replication begins
28
What is the initiation stage in interphase?
G1
29
How long does the S phase last for?
8 h
30
What happens during the S phase?
DNA replicates
31
What must happen during the S phase to ensure the prevention of cell death / diseases?
Precise + accurate DNA replication (prevent genetic abnormalities)
32
Describe the process of DNA replication?
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
What is specific about DNA helicase?
Untwists helix at specific locations = replication origins | -This forms a Y shape = replication fork
34
How long does the G2 phase last for?
4h
35
What happens during the G2 phase?
Enzyme + protein synthesis + replication of centrioles fully completed ( form the spindle apparatus)
36
What is the mitotic phase characterised by?
Karyokinesis + cytokinesis
37
What is karyokinesis?
Division of the nucleus
38
What is cytokinesis?
Division of the cytoplasm
39
How long does mitosis occur?
<1 h
40
What is the centrosome?
The main microtubule organising centre + regulator of cell-cycle progression
41
Kinetochore?
the protein structure on chromatids where the spindle fibres attach to pull the chromatids apart
42
Centromere?
Part of the chromosome that links sister chromatids | -Spindle fibres attach here via the kinetochore
43
What are chromatids?
Thread-like strands that containDNA helic
44
What is chromatin?
Complex of DNA + proteins that forms chromosomes
45
Prophase?
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
Prometaphase?
Nuclear envelope = breaks | Microtubules connect the kinetochores --> centrosomes
47
Metaphase?
The microtubules line-up the chromosomes at the cell's equator -Chromosomes = maximum coiling
48
Anaphase?
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
What is the longest sub-phase of mitosis?
Prophase
50
Telophase?
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
What marks the end of Karyokinesis?
Telophase
52
When does Cytokinesis begin?
At the end of anaphase + continues through telophase + beyonf
53
Cytokinesis?
``` 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
What regulates the initiation of cell-growth?
Cyclin-dependent kinases
55
``` Name the cyclin for each phase: G1 S G2 M ```
``` G1 = cyclin D ,CDK4 G1-S = cyclin E,CDK2 S = cyclin A,CDK2 G2 = cyclin A,CDK1 M = cyclin B,CDK1 ```
56
What are cell cycle checkpoints?
The control mechanisms that ensure the reliability of cell division -Asses DNA damage
57
What happens when a cell cycle checkpoint finds DNA damage?
Uses a signal mechanism -Stall cell cycle until repair OR -Target cell destruction via apoptosis
58
What is the restriction point and where is it found?
Late in G1 phase | - Cells that should cease dividing exit the cell cycle and enter G0
59
What cells continually divide ?
Haematopoietic stem cells | Gut epithelial cells
60
How do you overcome the G0 checkpoint?
The growth-factor induced expression of cyclin D proteins
61
What is the mitotic spindle checkpoint and when does it occur?
End of G2 phase | Occurs in metaphase when all the chromosomes should have aligned at the mitotic plate + be under bipolar tension
62
Describe the markers of cancer development?
``` Genetic mutation Hyperplasia Dysplasia In situ cancer Invasive cancer ```
63
Describe how cancer devleops?
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
When is anaphase blocked? When is DNA damage checkpoint entrance into S blocked? When is entrance into M blocked?
- Chromatids not properly assembled on mitotic spindle - Damaged genome - Uncompleted DNA replication

Alia - Biology (10 decks)

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