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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

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3
Q

What is Reproductive cell division ( Meiosis)?

A

When a diploid cell divides to form four haploid cells

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4
Q

What are the reasons for somatic cell division/mitosis?

A

Growth and development, tissue renewal, genetically identical daughter cells

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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, in which 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 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

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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 S?

A

8 hours

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15
Q

What is the G2 phase?

A

The phase of interphase where the cell prepares for cell division 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

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17
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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18
Q

What is the metaphase stage?

A

Spindles are fully formed and condensed chromosomes align along the equator

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19
Q

What is the anaphase stage?

A

Chromosomes (sister chromatids) separate, pulled by microtubules attached at the centromere to either pole of the cell

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20
Q

Telophase and Cytokinesis

A

When the nuclear envelope reforms in the two daughter cells and they cleave apart (cleavage furrow forms)

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21
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 (1/2 of a duplicated chromosome)

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22
Q

What is the centromere?

A

Part of chromosome that attaches the two sister chromatids

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23
Q

What does diploid mean?

A

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

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24
Q

What does haploid mean?

A

Half the amount of chromosomes in a cell (23 in human gametes)(n)

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25
Q

What are the mitotic cell cycle checkpoints?

A

G1, G2 and M

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26
Q

What is the G2 checkpoint?

A

Assesses if the cell is ready to divide

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27
Q

What is the G1 checkpoint

A

Checkpoint where the DNA is checked for damage, cell size and nutrition are checked, and the cycle proceeds if the appropriate signals are present

28
Q

What is the M checkpoint?

A

Checkpoint that ensures all chromosomes are attached to spindles (is in mitosis before anaphase and telophase and cytokinesis)

29
Q

What is cyclin?

A

A protein that regulates the mitotic cell cycle, accumulating towards G2 and degrading after mitosis

30
Q

What is cyclin dependant kinase (Cdk)?

A

A kinase that is activated when attached to cyclin

31
Q

What is M-phase promoting factor (MPF)?

A

A cyclin/Cdk complex that is key to the G2 checkpoint, phosphorylating many proteins and allowing mitosis to commence

32
Q

What do checkpoints rely on?

A

Cell signalling (Lots of signals contribute to checkpoints in the progression of the cell cycle)

33
Q

What are Mutations?

A

Permanent and random change to the base sequence of DNA

34
Q

What is translocation

A

Translocation is a common type of mutation in cancer where a chromosome breaks and a portion of it reattaches to a different chromosome

35
Q

What are acquired changes in DNA?

A

mutations occur at some time during a person’s life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun or virus or drugs, or can occur if a mistake is made as DNA copies itself during cell division

36
Q

What are inherited changes in DNA?

A

mutations that are inherited from parents that effects all cells. This is an inherited risk factor for cancer (susceptible genes)

37
Q

What are proto-oncogenes?

A

Are genes that stimulate cell proliferation/cell division

38
Q

What is an oncogene?

A

When a mutation occurs to a proto-oncogene, it turns into an oncogene which results in the formation of a hyperactive growth stimulating protein

39
Q

Examples of proto-oncogenes

A

Ras – GTPase protein that is susceptible to mutations that lead to tumours

Myc – A proto-oncogene that codes for a transcription factor

40
Q

What are tumour supressor genes?

A

Genes that keep cell proliferation/cell division in check (inhibits growth under certain conditions so that cell division occurs appropriately)

41
Q

What happens to a tumour supressor gene when it is mutated?

A

It forms a defective/non function protein so cell division is under no control

42
Q

Examples of tumour supressor genes

A

TP53, BRCA1, BRCA2 (BRCA’s are associated with breast cancer)

43
Q

What is a tumour?

A

groups of abnormal cells that form lumps or growths

44
Q

What are polyps?

A

Small benign growths that can develop into adenoma

45
Q

What is an adenoma?

A

A large benign tumour formed from glandular structures in epithelial tissue

46
Q

What is a carcinoma?

A

A cancer that develops from epithelial cells

47
Q

What is meiosis?

A

When a diploid cell divides into four haploid cells

48
Q

Where does meiosis occur?

A

In the gonads (ovaries and testes)

49
Q

What is fertilisation?

A

When two gametes come together to produce a diploid cell

50
Q

What is Meiosis I?

A

separates the pair of homologous chromosomes and reduces the diploid cell to haploid

51
Q

What are the stages of Meiosis I?

A 
PMAT 1
Prophase I 
Metaphase I 
Anaphase I 
Telophase I
Cytokinesis
52
Q

What is prophase 1?

A

Synapsis occurs, recombination and tetrads form

53
Q

What is synapsis?

A

Pairing of homologous chromosomes

54
Q

What is a tetrad?

A

The four chromatids in a pair of homologous chromosomes

55
Q

What is Recombination/crossing over?

A

When non-sister chromatids exchange sections

56
Q

What is a chiasmata?

A

A chiasmata is a point at which paired chromosomes exchange genetic material between non sister chromatids

57
Q

What is metaphase I?

A

Tetrads align themselves along equator of cell

58
Q

What is anaphase I?

A

Homologous chromosomes are pulled apart but sister chromatid stay attached

59
Q

What is meiosis II?

A

separates sister chromatids in a similar way to mitosis

60
Q

What is the metaphase plate?

A

Plane midway between the two poles of the cell where chromosomes line up during metaphase.

61
Q

Differences between mitosis and meiosis in DNA replication?

A

In mitosis it occurs during interphase before mitosis begins

In Meiosis it occurs during interphase before meiosis I but not meiosis II

62
Q

Differences between mitosis and meiosis in the number of divisions?

A

Mitosis has 1 division (including prophase, prometaphase, metaphase, anaphase and telophase)

In meiosis there are 2 divisions each including PMAT

63
Q

Differences between mitosis and meiosis in synapsis of homologous chromosomes?

A

Does not occur in mitosis

In meiosis it occurs during prophase 1 along with crossing over resulting chiasmata holds pair together due to sister chromatid cohesion

64
Q

Differences between mitosis and meiosis in number of daughter cells and their genetic composition?

A

Mitosis produces 2 daughter cells (2n) that are genetically identical to the parent cell with the same number of chromosomes

In meiosis there are 4 daughter cells (n) that are genetically different from the parent cell and each other

65
Q

What is independent assortment and how much variation does it produce ?

A

Homologous pairs line up randomly across the equator of the cell in metaphase 1 (223 >8 million possible combinations)

66
Q

When does crossing over occur and how much variation does it produce

A

at prophase 1 (~1-3 crossover events per pair)

67
Q

How much variation does fertilisation/fusion produce?

A

(> 223 times 223 combinations!!!)

BIOSCI 107 Part One (12 decks)

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