Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundations of Medicine > Cell Cycle > Flashcards

Cell Cycle Flashcards

1
Q

What is the cell cycle?

A

period of time between the birth of a cell and its own division to produce 2 daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How long does one full cycle take?

A

at least 12 hours but takes much longer in majority of adult tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 2 basic phases of the cell cycle?

A

Mitosis (M)
Interphase (G1,S,G2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are cyclins?

A
  • family of proteins that modify cells in interphase
  • activate CDKs (enzyme)
  • variable concentration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What occurs during S phase?

A
  • DNA replication
  • promoted by cyclin A and CDKs
  • begins 8 hours after the end of mitosis
  • takes ~8 hours to finish
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the structure of DNA.

A
  • 2 chains coiled around common helical axis
  • hydrophilic deoxyribose-phosphate backbone on outside
  • hydrophobic bases stacked on inside
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the spatial relationship between the 2 strands in the helix create

A
  • major groove (wide)
  • minor groove (narrow)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What can cause damage to DNA during replication?

A
  • deoxynucleotide incorporation error during replication
  • spontaneous deamination of bases during normal genetic functions
  • x-radiation causing nicks in the DNA
  • UV radiation
  • various chemicals that interact with DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List 3 disorders caused by defective DNA repair.

A
  • xeroderma pigmentosum
  • homologous recombination gene mutation
  • hereditary nonpolyposis colon cancer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the cause of xeroderma pigmentosum.

A
  • when DNA repair mechanisms are defective
  • DNA damaged by UV
  • results from inborn deficiency of the enzyme nicking endonuclease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the symptoms of xeroderma pigmentosum.

A
  • dry keratosis
  • hyperpigmentation
  • skin atrophy
  • increased cutaneous sensitivity to UV light
  • potential corneal ulcer formation
  • squamous cell carcinoma of the skin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe homologous recombination.

A
  • major pathway for the repair of DNA
  • defining step is strand exchange directed by RAD51
  • breast cancer suppressors BRAC1 and 2 are required
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What occurs if there is a mutation in one of the genes involved in homologous recombination?

A

mutations have been linked to tumour predisposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What causes hereditary nonpolyposis colon cancer

A
  • mismatch repair of DNA
  • chromosome 2 has been shown to contain genetic errors in the effected gene (hMSH2)
  • mutations of hMSH2 account for up to 60% of cases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When does G1 occur?

A

gap in the cycle between the end of mitosis and beginning of S phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What occurs during G1?

A
  • cells respond to growth factors directing the cells to initiate
  • irreversible
  • most molecular machinery required to complete another cell cycle is generated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What controls G1?

A

cyclin E and CDKs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How long does G1 take?

A
  • shows considerable variation
  • less than 2 hours in rapidly dividing cells
  • up to 100 hours in the same tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When does G0 occur?

A

after G1

20
Q

What occurs during G0?

A
  • undifferentiated cells go back into the cells cycle
  • no S phase
  • cells termed quiescent
21
Q

What stimulates cells to leave G0 and enter the cell cycle?

A

growth factors

22
Q

What blocks the cell cycle in G1?

A

proteins encoded by certain tumour suppressor genes

23
Q

When does G2 occur?

A

between the end of S and beginning of mitosis

24
Q

What occurs during G2?

A
  • cell prepares for division
  • ends with the breakdown of the nuclear membrane and onset of chromosome condensation
25
Q

What controls G2 phase?

A

cyclin B and CDKs

26
Q

How long does G2 last?

A

2 - 4 hours

27
Q

When does interphase occur?

A

just before mitosis

28
Q

Are chromosomes visible during interphase?

A

no
- uncoiled into very long narrow structures

29
Q

What occurs during interphase?

A
  • replication of DNA takes place in chromosomes
  • centrioles are located in cytoplasm
30
Q

What does the nucleus contain during interphase?

A
  • nuclear envelope
  • network of chromatin threads or granules
  • nucleolus
31
Q

What are the 4 phases of mitosis?

A
  • prophase
  • metaphase
  • anaphase
  • telophase
32
Q

What is the result of mitosis?

A

distribution of identical copies of the parent cell genome to the 2 daughter cells

33
Q

What occurs in prophase?

A
  • individual chromosomes are visualised as thin threads
  • threads tightly coiled along the entire length of cell
  • chromosomes spilt into 2 chromatids
  • 2 centrioles are separated from each other by elongation of continuous microtubules
34
Q

When does prometaphase occur?

A

between prophase and metaphase

35
Q

What happens during prometaphase?

A
  • nuclear membrane and nucleolus disappear
  • chromosomes now entangled in a meshwork of continuous microtubules
36
Q

What occurs during metaphase?

A
  • centromere region of each chromosome presents kinetochores
  • set of microtubules are organised and extend bilaterally towards opposite centrioles
37
Q

What does the growth of microtubules during metaphase allow?

A

permits the centromere of individual chromosomes with their paired chromatids to occupy equatorial plane of the spindle

38
Q

What is the role of colchicine in the cell cycle?

A
  • arrests cell division at metaphase
  • prevents formation of microtubules of the spindle
  • chromosomes don’t align properly during metaphase
39
Q

What occurs during anaphase?

A
  • separation of genetic material
  • centromeres split longitudinally
  • chromatids form 2 new chromosomes
  • spindel fibres contract
  • new chromosomes separated and migrate to opposite poles
40
Q

What is non-disjunction?

A

when one daughter cell receives extra chromosomes and the other daughter cell is deficient in those chromosomes

41
Q

How does non-disjunction occur?

A
  • abnormal function of spindle apparatus
  • one or more chromosomes fail to migrate properly in anaphase
42
Q

What is isochromosome?

A

formation of 2 daughter chromosomes of unequal length

43
Q

How does isochromosome occur?

A

when the centromere splits transversely instead of longitudinally

44
Q

What occurs during telophase?

A
  • reorganisation period
  • daughter chromosomes enveloped by new nuclear membrane and nucleolus appears
  • chromosomes become uncoiled and individual identity is lost
45
Q

What occurs by the end of telophase?

A
  • cytoplasm divides
  • 2 complete cells formed

Foundations of Medicine (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions