growth factors Flashcards

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1
Q

what do growth factors stimulate and how does it work

A

. cellular growth
. proliferation
. regeneration
. cellular differentiation

they bind to target cells by specific receptors on cell membrane

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2
Q

growth factors examples

A

KGF - Growth + new keratinocyte gen

PDGF - growth, new gen, repairs blood vessels, collagen prod (platelet derived)

VEGF - promotion of angiogenesis + wound healing ( vascular endothelial)

EGF - promotion of epithelial cell growth, angiogenesis + wound healing (epidermal)

FGF - present in epithelialization phase of wound healing. keratinocytes cover wound making epithelium. (fibroblasts)

IGF - cell growth regulation (insulin)

TGF-B - growth + neogenesis of epithelial cells + vascular endothelial cells. prom wound healing (transforming beta)

CTGF - promotes angiogenesis, cartilage regen + platelet adhesion (connective tissue)

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3
Q

how does growth factor allow cell to grow

A

contact btw GF + receptor stimulates enzyme activity of cytoplasmic domain of receptor.
signal gets to nucleus, genes then resposible to start replication + prep for mitosis
proteins for g1-s transition made.

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4
Q

what do embryonic pluripotent stem cells

A

differentiates into endo, ecto, mesoderm + unlimeted self renewal capacity
***but eithical issues so scientists use induced pluripotent stem cells.

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5
Q

what are iPSCs

A

manipulated somatic cells (undifferentiated) but are able to differentiate
with growth factors they turn into progenitor cells (organ/tissue development)

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6
Q

What Organoids used for

A

. normal organ development
. pathology in organ development
. drug effects

they can self organize therefore mimic general tissue structure + development found in IN VIVO. also in them, diff cells can help eachother to differentiate

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7
Q

parts of a 3D bioprinting sytstem and what it does

A

. controller
. dispensing module
. closed acrylic chamber wth temp controller + humidifier

to imitate target tissue/organs

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8
Q

in tumour suppressor genes if mutated, is it recessive or dominant mutation.
Under what conditions

A

recewssive allele

As long as cell contains 1 normal alelle, tumour suppression continues

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9
Q

Mutations in individuals with heterozygous tumour suppressor gene

A

Mutation causes the normal copy of the gene to become mutated = LOSS OF HETEROZYGOSITY

so cell turns into cancer cell

That is why, at the cell level mutations
in tumor suppressors are recessive,
but for the whole organism they are
dominant.

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10
Q

What is retinoblastoma and what can it do

A

Retinoblastoma Rb is a tumour suppressor gene

It can: inhibit cell division without permission, inhibit cell division even when permission for mitosis is given ( cell doesnt complete requirements for mitossi eg damaged DNA)

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11
Q

What are the 2 forms of Rb

A

Dephosphorolated= inhibits replication and forbids mitosis

Phosphorylated= When permission given, it tuns into Phosopho-Rb and liberated cell replcation and aloows mitosis

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12
Q

What is E2F

A

Transciptional factor that triggers expression of set of genes to start DNA replication

If there is no signal to start
mitosis, Rb blocks E2F.
Phospho

-Rb liberates E2F.

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13
Q

How is the activation chain for DNA rplication

A
  • growth factor binds onto receptor of cell
  • Receptor activated in cytoplasmic region
  • Causes activation of protein kinases in cytoplasm
  • One of the activated kinases enters the nucleus and adds
    phospho groups to Rb.
  • Phospho-Rb liberates E2F.
  • Replication is triggered.
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14
Q

Why the mutant recessive Rb may behave as dominant?

A

Loss of heterozygosity

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15
Q

P53 is a tumour suppressor gene like Rb.
What happens if a person only inherits 1 functional copy

A

Li Frsaumeni syndrome
You are predisposed to ccancer

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16
Q

If P53 is activated, what can it do

A
  • Cell cycle arrest for DNA repair
  • Apoptosis to discard damaged cells
17
Q

Protooncogenes vs oncogenes

A

Proto oncogenes code for proteins that positivily stimulate cell cycle

They can become oncogenes due to mutations or overexpression=cause tumour

18
Q

How can a proto oncogene lose its function

A
  • Change in protein structure causing increase in protein activity
  • gene duplication/amplification
  • loss of regualtion
19
Q

Do oncogene behave as dom or rec
Are they only due to mutations/overexpression of protooncogenes

A

Behave as dominant= 1 mutant allele predisposes to tumour form

Oncogenes can be introduced into cells by onconogenic viruses