Brainscape's Knowledge GenomeTM

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


See full index

Molecular Basis of Disease > Mechanism Of Disease 1: Cell Growth and Cell Differentiation > Flashcards

Mechanism Of Disease 1: Cell Growth and Cell Differentiation Flashcards

1
Q

What is cell growth and cell differentiation? (which comes first)

A

Cell growth = multipotent cells (stem cells) divide to produce more cells
Differentiation = cells become specialised + more complex (lose potency) ending growth

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

How can cell grwoth + differentiation lead to disease?

A

Developmental conditions (e.g. neural tube defects - spina bifida)
Neoplasia (+ metaplasia) - cancer and tumours
Cell growth related e.g. cardiac hypertrophy

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

What is metaplasia?

A

Replacement of one differentiated somatic cell type to another in same tissue (uncontrolled during reproduction = metaplasia, otherwise normally required)

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

What is a somatic cell?

A

Any cell apart from a gamete, germ cells and undifferentiated stem cells.

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

What are the 2 types of cell growth?

A

Hypertrophy - bigger cells

Hyperplasia - more cells - more common

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What causes hypertrophy? + example

A

Cells grow bigger due to elevated protein synthesis so more proteins, lipid and nucleotides produced.
Example - heart (cardiac hypertrophy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes hyperplasia?

A

Increased cell division/proliferation due to cell cycle - more cells produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the steps in cell differentiation?

A
  • Cell exits cell cycle becoming “post-mitotic”
  • Cell type specific expression
  • Specific gene expression causes cell morphology and function changes
    (terminally differentiated and can’t return to cell cycle)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which mechanism controls cell growth and differentiation?

A

Intra and extracellular signals e.g. checks on cells, growth and inhibitory factors, cell adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do intra/extracellular signals interact to cause cell growth/differentiation?

A

On promoters as co-incidence detectors. (multiple factors required to decide if gene will be expressed or not)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Wha are the steps for extracellular signals?

A

Ligand (e.g. a growth factor) binds to receptor causing intracellular cascade (e.g. kinase cascade)
Cascade causes transcription factor activation in nucleus + downstream genes are expressed.
mRNA produced and proteinsynthesis occurs (translation).
Proteins produced go onto directly affect the cell or cause more transcription factors to affect downstream genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 3 types of extracellular signals?

A

Paracrine
Autocrine
Endocrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are paracrine extracellular signals?

A

Cell non-autonomous example
Ligands produced locally (near cell) to stimulate proliferation of a different cell type with correct cell surface receptor

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

What are autocrine extracellular signals?

A

Cell autonomous example

Ligand produced by own cell and affects itself by attaching to own appropriate receptors (produces own cascade)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are endocrine extracellular signals?

A

Like hormones. Released systemically (into general circulation) for distant effects

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

What are the 4 different effects of the extracellular signalling proteins? + example proteins for each

A
  • Stimulate proliferation via mitogens (e.g. EGF, IL2)
  • Induce differentiation + inhibit proliferation (e.g. TGFbeta)
  • Can do either cell proliferation or differentiation (e.g. Wnt ligands)
  • Induce apoptosis (e.g. TNF family e.g. TNFa)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are mitogens? + examples

A

Protein that induces cell division e.g Growth factors and interleukins such as EGF, FGF, NGF, IGF1, IL2, IL4)

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

What are the phases of the cell cycle?

A 
G1 phase (growth)
S phases (synthesis of DNA) - DNA replication
G2 phase (growth)
M phase (mitosis)
G0 phase - quiescent cells (left cell cycle)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens to quiescent cells? - entire journey

A

Cells in G0 phase either rejoin cell cycle or undergo terminal differentiation (post-mitotic cell) which after it’s lifespan undergoes apoptosis (cell shedding)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which part of cell cycle is ploidy 2N?

A

Diploid in G1 phase before DNA replication in S phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which part of cell cycle is ploidy 4N?

A

Tetraploid in G2 phase after DNA replication in S phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What stages are in interphase?

A

G1, S and G2

23
Q

How do we look at cells in the cell cycle? + determine which stage they’re in (2 methods)

A
  • DNA stain applied and FACs measure DNA content of every cell in a. population
  • Fluroscence microscopy
24
Q

How would FAC analysis graph look if rate of division was low and why?

A

G1 would be vert high showing cells aren’t too proliferative. S would be lowest and G2/M slightly higher

25
Q

How would FAC analysis graph look if rate of division was high and why?

A

G1 is much lower wherease S is much higher. G2/M stays the same because it’s a time limited part of cycle.

26
Q

What does fluorescence microscopy show? - look at pictures in detail

A

Shows interphase as 1 phase and all phases of mitosis by showing presence of tubulin, CHEK 2 (mitotic protein) co-localised and centrioles.

27
Q

What are the phase of mitosis and what happens in each phase?

A 
Prophase
- nucleus less definite 
- microtubular spindle assemble and centrioles migrate to poles
Prometaphase
- nuclear membrane breaks down
- Kinetochores attach to spindle 
Metaphase
- Chromosomes align in equatorial plane
Anaphase
- Chromatids separate and migrate to opposite poles
elophase
- Daughter nuclei form
Cytokinesis
- Division of cytoplas
- Chromosomes decondense
28
Q

What are the 3 cell cycle checkpoints?

A

1 - restriction point (most important) - checks if DNA not damaged, cell size and metabolite stores
2 - G2/M phase checkpoint - checks if DNA completely replicated and DNA not damaged
3 - M phase checkpoint - checks if chromosomes are aligned on spindle so there will be the right number of chromosomes in each daughter cell

29
Q

Why are there cell cycle checkpoints?

A

Makes sure synthesis (S phase) and mitosis (M phase) is separated so mitosis only occurs when DNA is completely synthesised and vice versa.

30
Q

Why is the restriction point the most important cell cycle checkpoint?

A

Cell are responsive to growth factors (extracellular signals) in G1 phase before restriction point. This allows cell growth and the point determines if G0 cells have re-entered cell cycle.

31
Q

What controls the cell cycle?

A

Controls such as protein kinases and phosphatases to ensure strict alternation of mitosis and DNA replication.

32
Q

What do protein kinases and phosphotases do?

A

Protein kinases attach phosphate groups.

Phosphotases remove phosphate groups (dephosphorylate)

33
Q

What are CDKs?

A

Cyclin dependent kinase - type of protein kinase catalysing phosphorylation of specific substrates

34
Q

What are cyclins?

A

Regulatory subunit that must bind to CDK for it to function.

35
Q

What are the steps of active cyclin-CDK complex forming?

A

Expression of cyclin due to extracellular signals (growth factors). When there is enough it binds to CDK forming the active cyclin-CDK complex which can now go onto phosphorylate specific substrates.

36
Q

What 4 ways is Cyclin-CDK activity self-regulated?

A
  • Cycle of synthesis (of cyclin via gene expression) and destruction of cyclins (by proteosomes)
  • Post-translational modifications phosphorylate cyclins (can cause activation, inhibition, or destruction - increase target for proteosome)
  • Dephosphorylation
  • Binding of cyclin-dependent kinase inhibitors (CDKIs)
37
Q

What is retinoblastoma protein (RB)?

A

RB is a key substrate of G1 and G1/S cyclin dependent kinases (CDKs).
It is a tumour suppressor preventing cell cycle entry by keeping E2F bound to it.

38
Q

What are the steps for CDK and Retinoblastoma protein causing DNA replication?

A

In normal conditions unphosphorylated RB protein is bound to E2F which prevents stimulation of S phase protein expression.

Cyclin D-CDK4 and Cyclin E-CDK2 phosphorylates RB releasing E2F.

E2F now stimulates cyclin E expression (+ve feedback) and S phase protein allowing DNA replication to begin.

39
Q

What is E2F?

A

It is a transcription factors that normally binds to a promoter driving transcription and allowing S phase protein expression.

40
Q

Give examples of S phase proteins?

A

DNA polymerase, thymidine kinase, PCNA

41
Q

What are the steps in the entire cycle for RB proteins causing mitosis (entry into cycle)? - long

A

1) Mitogens triggers entire process in G1 phase by signalling to nucleus + induces transcription of early genes
2) Early gene make transcription factors that drive delayed gene transcription.
3) Delayed gene transcription makes cyclin D.
4) Cyclin D-CDK4/6 active complex forms and hypophosphorylates (some E2F activity)
5) E2F activity increases cyclin E forming cyclin E-CDK2 active complex.
6) This complex hyperphophorylates RB - loses ability to suppress E2F
7) E2F +ve feecbacks for cyclin E and activates E2F responsive genes required for S phase due to hyperphosphorylation of RB
8) Cyclins continuously activate more in a cycle

End of mitosis only when RB dephosphorylated by PP1 (phosphotase)

42
Q

When do S phase cyclin-CDKs and G2/M phase cyclin-CDKs cause cell to go through S phase and mitosis?

A

They are initially in inactive forms but switched activated by post-translational modifications and inhibitors removed allowing cell to progress through S phase and mitosis.

43
Q

What 3 steps occur during the cell cycle if DNA damage detected at a checkpoint?

A

1) Stop the cell cycle (using CDKIs and CHEK2) - CDKI genes expressed
2) Attempt DNA repair e,g mismatch repair
3) Too much damage and repair impossible = programmed cell death (apoptosis) by BCL2 family and capsases which are involved in apoptosis (genes activated to produce them)

44
Q

What is TP53?

A

Tumour protein p53 involved in cell cycle and apoptosis (tumour suppressor gene, similair to Rb gene)

45
Q

Steps of TP53 activation

A

1) Mutagen damages DNA
2) Damage causes kinase activation leading to Tp53 phosphorylation (Tp53 now activated and can’t be destroyed by proteosome)

46
Q

What are the 3 biological effects of Tp53?

A

1) Drives transcription for expression of CDK1 - so cell cycle arrests
2) DNA repair e.g excision repair
3) If repair not possible and cell can’t return to cell cycle, Tp53 causes apoptosis

47
Q

What are Tp53 levels when DNA is not damaged?

A

Tp53 low as it is continuously destroyed by proteosomes until it’s phosphorylated due to kinase activation

48
Q

How does Tp53 lead to cancer?

A

Loss of TP53 funcition mutations

  • prevents cells cycle arrest after DNA damage so faster growth
  • prevent apoptosis - damaged cells don’t die
  • prevent DNA repair - more mutations = cancer progression
49
Q

How does chemotherapeutic drugs work?

A

The drugs act on the cell cycle to stop proliferation and induce apoptsosis.

50
Q

What do S phase chemotherapeutic drugs do + 2 drug examples?

A

S phase drugs cause DNA damage

5-fluorouracil (prevent thymidine synthesis)
Cisplatin (binds to DNA causing damage and blocks repair)

51
Q

What do M phase chemotherapeutic drugs do + 2 drug examples?

A

M phase drugs target mitotic spindle

Vinca alkaloids - bind to free monomeric tubulin and stabilise them. Prevent microtubule polymerisation so mitotic spindle can’t form and cells arrest in mitosis

Paclitaxel (taxol) - bind to polymerised tubules and stablise microtubules to prevent de-polymerisation arresting cells in mitosis

52
Q

What is colchicine? + what does it do

A

A M phase drug (same mechanism of vinca alklaloids)

- used as immunosuppressant

53
Q

Explain which cyclin-CDKs are activated when?

A

When growth factors binds to receptor and induce gene expression, cyclins are made.

G1 and G1/S cyclin CDKs phosphorylate substrate when CDKI not present
S phase cyclin CDKs cause DNA replication (gene expression of S phase proteins)
G2/M cyclin CDKs cause cells to enter mitosis if all DNA is replicated as chromosomes align on spindle

Failure = TP53 cause apoptosis

54
Q

What regulates CDKIs?

A

TP53 and TGF beta

Molecular Basis of Disease (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions