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Advanced Higher Biology > Unit 1 - Protein Control of Cell Division > Flashcards

Unit 1 - Protein Control of Cell Division Flashcards

1
Q

What is the cytoskeleton?

A

A microscopic network of proteins and tubules in cytoplasm, that supports the shape and function of cells

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2
Q

What are microtubules?

A

Microscopic hollow tubes made of tubulin that are part of cell’s cytoskeleton

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3
Q

What is tubulin?

A

The protein that polymerises into long chains or filaments that form microtubules

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4
Q

What is the microtubule organising centre?

A

The structure found in eukaryotic cells from which microtubules are produced for the formation of spindle fibres

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5
Q

What are spindle fibres?

A

Microtubules to which the chromosomes are attached by kinetochores during cell division

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6
Q

What is the cell cycle?

A

A 4 stage process in which the cell increases in size, copies its DNA, prepares to divide and divides by mitosis

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7
Q

What is mitosis?

A

The division of the nucleus to form two nuclei, each with a full complement of chromosomes

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8
Q

What is cytokinesis?

A

The division of cytoplasm to form two daughter cells

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9
Q

What are kinetochores?

A

A complex of proteins associated with the centromere of a chromosome during cell division, to which the microtubules of the spindle attach

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10
Q

What is the centromere?

A

The specialised DNA sequence of a chromosome that links a pair of sister chromatids

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11
Q

What are cyclin proteins?

A

Proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinase enzymes

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12
Q

What do cyclin-dependent kinases cause?

A

The phosphorylation of proteins, which stimulates the cell cycle

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13
Q

What is p53?

A

A tumour-suppressor protein that is dysfunctional in several major cancers

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14
Q

What is p53?

A

A tumour-suppressor protein that can stimulate DNA repair, arrest the cell cycle or cause cell death by activation of caspases

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15
Q

What is proto-oncogene?

A

A normal gene, usually involved in the control of the cell growth or division, which can mutate to form a tumour-promoting oncogene

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16
Q

What is tumour-promoting oncogene?

A

A mutated proto-oncogene that has the potential to cause cancer

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17
Q

What is apoptosis?

A

Programmed cell death triggered by cell death signals that can be external or internal

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18
Q

What are death signal molecules?

A

External or internal signals that result in the activation of protease enzymes called caspases, which cause apoptosis

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19
Q

What are caspase cascades?

A

Protease enzymes involved in a series of reactions that destroy a cell

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20
Q

What is metamorphosis?

A

The process that involves a significant change in an organism’s physical form during development

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21
Q

What are growth factors?

A

A naturally occurring substance, usually a protein or steroid hormone, capable of stimulating cell growth

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22
Q

What does the cytoskeleton consist of?

A

Different protein strctures including microtubules

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23
Q

What are microtubules?

A

Hollow cylinders composed of tubulin.

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24
Q

Where do microtubules radiate from?

A

MTOC ( Microtubule organising centre)

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25
What does the formation and breakdown of microtubule involve?
-Polymerisation of tubulin (growth of microtubule) -Depolymerisation of tubulin (shrinkage of microtubule)
26
What are the functions of the cytoskeleton?
- Gives mechanical support and shape to cells - Microtubules control membrane-bound organelles and chromosomes - Microtubules form spindle fibres that are active during cell division
27
What is cell division required for?
Growth and repair
28
What are the 2 parts of the **cell cycle**?
- Interphase - Mitotic phase
29
What phase lasts longer, Interphase or mitotic phase?
Interphase
30
What are the 3 **sub-phases** of interphase?
- G1 - S phase - G2
31
What happens during **G1** sub-phase?
Growth period where proteins and organelles are synthesised
32
What happens during **S phase**?
Cell continues to grow, DNA is replicated in prep for mitosis
33
What happens during **G2 sub-phase**?
Another growth period where proteins and organelles are synthesised?
34
What are the 2 sub-phases of the **mitotic phase**?
- Mitosis - Cytokinesis
35
What happens during mitosis?
Chromosomal material is separated by spindle microtubules
36
What happens during cytokinesis?
The cytoplasm separates into two daughter cells
37
What are the 4 stages of mitosis?
- Propase - Metaphase - Anaphase - Telophase ( Pass Me Another Tequila )
38
What happens during **prophase**?
- DNA condenses into chromosomes, both have two sister chromatids. - Nuclear membrane breaks down - Spindle microtubules extend from MTOC by polymerisation and attach to chromosomes via kinetochores in centromeme
39
What happens during **metaphase**?
- Chromosomes are aligned at the metaphase plate (equator of spindle)
40
What happens during anaphase?
As spindle microtubules shorten by depolymerisation, sister chromatids are separated, and the chromosomes are pulled to opposite poles
41
What happens during telophase?
The chromosomes decondense and nuclear membranes are formed around them
42
What happens after telophase?
Cytokinesis
43
What is cytokinesis?
When the cell splits to give two daughter cells
44
Timing and rate of cell division is crucial for…
Normal growth, development and maintenance of tissues
45
How is the cell cycle controlled and regulated?
By checkpoints
46
Why must the cell cycle be controlled?
To ensure that events proceed in the correct order and are completed before the next starts
47
What do checkpoints do?
They assess condition of the cell during the cell cycle and halt progression to the next phase until requirements are met
48
What are the 3 checkpoints?
G1, G2 and M
49
When does G1 checkpoint occur?
The end of G1
50
What does the G1 checkpoint ensure?
That sufficient cell growth has occurred before the cell enters S phase.
51
Proteins that regulate progression from G1 checkpoint
- Cyclin - Retinoblastoma - p53
52
What happens when the cell size increases at G1?
Cyclin proteins accumulate
53
What do cyclins do?
Combine and activate cyclin-dependent kinases (CDK)
54
What does CDK do?
Phosphorylates proteins that regulate progression through the cell cycle
55
What is retinoblastoma?
A protein that acts as a tumour suppressant
56
What does retinoblastoma do at the G1 checkpoint?
Inhibits the transcription of genes that code for proteins needed for DNA replication
57
How is retinoblastoma inhibited?
The phosphorylation of G1 Cyclin-CDK
58
When does the G2 checkpoint occur?
The end of G2 stage
59
What happens at the G2 checkpiint?
The success of DNA replication and any damage to DNA is assessed
60
What does DNA damage trigger?
The activation of p53
61
What does p53 do?
-Stimulate DNA repair -Arrest the cell cycle -Initiate apoptosis
62
What happens at the metaphase checkpoint?
Progression is halted until the chromosomes are aligned correctly on the metaphase plate and attached to the spindle microtubules
63
What can an uncontrolled *reduction* in rate of cell cycle lead to?
Degenerative diseases like alzheimers
64
What can an uncontrolled *increase* in the rate of cell cycle lead to?
Tumour formation
65
What is proto-oncogene?
A normal gene which can mutate to form a tumour-promoting oncogene
66
What is apoptosis?
Programmed cell death
67
What is apoptosis triggered by?
Cell death signals that can be external or internal
68
What is an example of an external cell death signal?
The production of death signal molecules from lymphocytes
69
What do external death signals do?
Bind to surface receptor protein and trigger a protein cascade within the cytoplasm
70
What is an example of internal death signal?
DNA damage
71
What do internal death signals do?
Causes activation of p53 tumour-suppressor proteins
72
What are caspases?
A type of protease enzyme
73
74
What do proteases do?
Bring about degradation of cellular proteins, causing destruction of cell
75
When else can apoptosis be initiated?
In the absence of growth factors
76
Why is apoptosis essential?
It removes cells that are no longer required as development progresses

Advanced Higher Biology (9 decks)

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