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BIOSCI 107 Part One > Cell Structure and Function - Cell Division and Cancer > Flashcards

Cell Structure and Function - Cell Division and Cancer Flashcards

1
Q

What is a Eukaryotic Cell?

A

cells that have a nucleus enclosed within membranes

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2
Q

What is Somatic cell division (Mitosis)?

A

When a diploid cell divides to form two diploid daughter cells (genetically identical to parent cell)

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3
Q

What is Reproductive cell division ( Meiosis)?

A

When a diploid cell divides to form four haploid cells (genetically DIFFERENT from the parent cell)

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4
Q

What are the reasons for somatic cell division/mitosis?

A

Growth and development, tissue renewal

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5
Q

Examples in the body were mitosis for cell growth is needed

A

Skin and blood cells

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6
Q

Examples of cells that do not/require little division

A

Muscle and Neuron cells

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7
Q

What phase do most cell spend the majority of their time?

A

G1 of interphase

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8
Q

What is interphase?

A

Metabolic phase of the cell

The cell obtains nutrients and metabolizes them, grows, reads its DNA, and conducts other “normal” cell functions

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9
Q

What are the three stages of interphase?

A

G1, S, G2

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10
Q

What is G0?

A

If cells do not divide they stay in G0 which means they do not progress past G1 of interphase

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11
Q

What is the G1 phase?

A

The phase of interphase where most cellular activity occurs (cell is metabolically active, duplicated organelles, centrosome replication begins)

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12
Q

How long is G1?

A

The duration of this phase depends on the cell but usually between 8-10 hours
(Maybe more or even less in some cases)

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13
Q

What is the S phase?

A

The phase of interphase where DNA is replicated

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14
Q

How long is the S phase?

A

8 hours

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15
Q

What is the G2 phase?

A

The phase of interphase where the cell prepares for M phase by synthesising proteins and enzymes, gathers reagents, replicates centrosomes

Also checks for correct DNA synthesis for the mitotic phase

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16
Q

What are the four stages of the mitotic phase?

A

PMAT
Prophase, metaphase, anaphase, telophase and cytokinesis
(Please make another two CELLS )

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17
Q

What is in the interphase? (Start of cell division images)

A

Made up of G1, S, G2
Chromosome are un-condensed
DNA exists as chromatin
Nuclear envelope is intact

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18
Q

What is the prophase stage?

A

Mitotic spindle forms (made of microtubules), chromatin condenses into chromosomes, nuclear envelope disappears and chromosomes begin to line up

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19
Q

What is in the metaphase stage?

A

Spindles are fully formed and condensed chromosomes align along the equator (M=iddle)

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20
Q

What is the anaphase stage?

A

Chromosomes (sister chromatids) separate, pulled by microtubules attached at the centromere to either pole of the cell
This is due to the shortening of the mitotic spindle fibres attached to each sister chromatid

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21
Q

What occurs in Telophase and Cytokinesis?

A

When the nuclear envelope reforms in the two daughter cells and they cleave apart (cleavage furrow forms, the indentation of the cell membrane as cell division occurs)

When two independent nuclei have formed, mitosis is complete.

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22
Q

What are sister chromatids?

A

refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere

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23
Q

What is the centromere?

A

Part of chromosome that attaches the two sister chromatids

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24
Q

What does diploid mean?

A

Full amount of chromosomes in a cell (46 in humans)(2n)

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25
What does haploid mean?
Half the amount of chromosomes in a cell (23 in human gametes)(n)
26
What are the mitotic cell cycle checkpoints?
G1, G2 and M
27
What is the G2 checkpoint?
Assesses if the cell is ready to divide
28
What is the G1 checkpoint
Checkpoint where the DNA is checked for damage, cell size and nutrition are checked, and the cycle proceeds if the appropriate signals are present
29
What is the M checkpoint?
Checks for the mitotic spindle attachment
30
Why are cell cycle checkpoints important?
They keep cells in a certain stage or stimulate progression into the next staged if the cells are deemed PERFECT If not done, could lead to cancer
31
What is cyclin?
A protein whose levels fluctuate throughout the cell cycle and regulates the mitotic cell cycle It accumulates towards G2 and degrades after mitosis
32
What is cyclin dependent kinase (cdk)
An enzyme that is activated when bound to cyclin | It phosphorylates proteins
33
What is M-phase promoting factor (MPF)?
A cyclin/cdk complex that is key to the G2 checkpoint, phosphorylating proteins and hence allows mitosis to commence
34
What is MPF made up of?
Cyclin and cdk
35
What do checkpoints rely on?
Cell signalling (Lots of signals contribute to checkpoints in the profession of the cycle)
36
What are mutations?
A permanent, random change to the base sequence of DNA
37
What is translocation
Common type of mutation in cancer | Where a chromosome breaks and a portion of it reattaches to a different chromosome
38
What are acquired changes in DNA?
Often due to viruses, drugs, treatment of UV damage Only in certain cells, not every cell in the body Can occur is a mistake is made as DNA copies itself during cell division
39
What are inherited changes in DNA?
Are mutations inherited from parents. Affect all cells and affect susceptibility genes which are genes that are more likely to develop into cancer
40
What are proto-oncogenes?
Are genes that stimulate cell proliferation/cell division | ACCELERATOR
41
What is an oncogene?
When a mutation occurs to a proto-oncogenes they turn into an oncogene This results in the formation of a hyperactive growth stimulating protein
42
Examples of proto-oncogenes
Ras - GTPase protein that is susceptible to mutations that lead to tumours Myc - A proto-oncogene that codes for a transcription factor
43
What are tumour supressor genes?
Produce a normal growth inhibiting protein so that cell division remains under control
44
What happens to a tumour supressor gene when it is mutated?
Produces a defective/non-functioning protein so cell division goes out of control and causes cancer
45
Examples of tumour supressor genes
TP53, BRCA 1, BRCA 2
46
What is a tumour?
Groups of abnormal cells that form lumps or growths
47
What are polyps?
Small begnign growths that can develop into adenoma
48
What is an adenoma?
A large begnign tumour formed from glandular structures in epithelial tissues
49
What is a carcinoma?
A cancer developing from epithelial cells
50
What is meiosis?
When a diploid cell divides into four haploid cells
51
Where does meiosis occur?
In the gonads (ovaries and testes)
52
What is fertilisation?
When two gametes come together to produce a diploid cell
53
What is Meiosis I?
The pairs of homologous chromosomes are separated, making the cell go from diploid to haploid
54
What are the stages of Meiosis I?
``` PMAT 1: Prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Cytokinesis ```
55
What is prophase 1?
Synapsis occurs recombination tetrads form
56
What is synapsis?
Pairing of homologous chromosomes (they come together)
57
What is a tetrad?
The four chromatids in a pair of homologous chromosomes
58
What is Recombination/crossing over?
When non-sister chromatids exchange sections
59
What is a chiasmata?
The point of contact between 2 chromatids | The point at which genetic material can be exchanged between chromatids
60
What is metaphase I?
Homologous pairs of chromosomes line up randomly along the metaphase plate
61
What is anaphase I?
Spindle fibres shorten Homologous chromes are pulled apart to opposite poles of the cell Sister chromatids remain attached to each other
62
What is meiosis II?
Separates sister chromatids in a similar way to mitosis
63
What is the metaphase plate?
Plane midway between the two poles of the cell, is where chromosomes line up during metaphase
64
Differences between mitosis and meiosis in the number of divisions?
``` Mitosis = 1 division (including PMAT) Meiosis = 2 divisions (including PMAT) ```
65
Differences between mitosis and meiosis in synapsis of homologous chromosomes?
Does not occur in mitosis In meiosis occurs in prophase 1 EDIT THIS CARD LATER
66
Differences between mitosis and meiosis in number of daughter cells and their genetic composition?
Mitosis produces 2, diploid, daughter cells that are genetically identical to the parent cell (both have 46 chromosomes) Meiosis produces 4, haploid, daughter cells that are genetically different from the parent cell and each other due to crossing over, independent assortment etc
67
What is independent assortment and how much variation does it produce ?
Homologous pairs line up randomly upon the metaphase plate during metaphase 1. >8 million combinations possible
68
When does crossing over occur and how much variation does it produce
At prophase 1 | Approximately 1-3 crossover events per pair
69
How much variation does fertilisation/fusion produce?
> 223 combinations possible

BIOSCI 107 Part One (12 decks)

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