Lecture 10 - Growth and Cancer Flashcards

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1
Q

What drives the cell cycle forwards?

A

The kinases Cyclins and Cdks

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2
Q

How do drosophilia grow ?

A
  1. Form a Syncytium- lots of nuclei in ONE CELL
  2. First 14 cycles of cell division is rapid (only S and M).
  3. Inside 14th cycle it slows and phase G1and G2 is introduced.
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3
Q

What is String protein and how is it relevant to the cell cycle ?

A

String protein, after 14th cycle maternal string runs out you are only left with foetal string
String - activates Cdks which drives the cell cycle
It is first expressed in the mesoderm (one of the last bits to form because tribble is expressed in mesoderm as well, tribble inhibits string. because you need time to form ventral furrow)

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4
Q

What does the rate of cell division in dropholia embryo depend on ?

A

Rate of cell divison in drosopholia embryo depends on cell location.
This creates mitotic domains, this is all based on String

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5
Q

What are the 2 ways in which organs grow?

A

Intrinsically and extrinsically

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6
Q

How can organs grow intrinsically?

A

Intrinsically - the organ knows the size it needs to be

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7
Q

How can organs grow extrinsically

A

The body and surrounding areas signal to the organ

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8
Q

What is organ size dependent on ?

A

Organ size is dependent on organ size not cell number

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9
Q

What was the experiement using a thymus and spleen to prove ex and intrinsic growth ?

A
  1. Took the thymus of a dif organism and transported it into another one
  2. The thymus stayed the same ze
  3. Whe done with a spleen the spleen got smaller
  4. Spleen was being controlled intrinsically/systemic
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10
Q

What are the 2 growth pathways?

A

TOR pathway
Hippo pathway

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11
Q

What is the difference between TOR and Hippo pathways ?

A

TOR - increases cell size
Hippo - (MST1/2) limits organ size

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12
Q

What does Hippo do after activation?

A

Hippo activates 3 proteins. YAP, TAZ and Yka
When Hippo is activated these proteins are not in the nucleus and prevents cells from increasing in size
HIPPO inactive stimulates cell growth, blocks things because it is big

Mutation in HIPPO = overgrowth

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13
Q

What does the size of drosophila depend on ?

A

In drosophila its size depends on insulin signalling

Insulin-defiecient = remain small with smaller and fewer cells

Maternal environment influences growth

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14
Q

What does the size of a human depend on ?

A

In humans it depends on our second growth spurt and insulin and growth hormones

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15
Q

How are human growth hormones released?

A
  1. GHRH, released from hypol=thalamus
  2. Causes pituitary gland to release growth hormone
  3. Somatostatin is also released from the hypothalamus but inhibits growth hormone release.
  4. Growth hormone allows IGF to be released
  5. IGF is released from the liver or local cells
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16
Q

How do ANthropods molt in order to form new cuticles ?

A

Corpus Allatum gland releases prothoracic hormone, this stimulates prothoracic gland, this releases ecdyson and causes apoplysis.

Allows growth

The pathway that inhibits this is done by the molecule juvenile hormone.
Released by Corpus Allatum.

Inhibits growth

17
Q

In frogs what allows their metamorphosis (growth)?

A

CRH is released from the hypothalamus. This stimulates the pituitary gland to release TSH. This stimulates the thyroid gland to release thyroxine

Allows growth

Prolactin in frogs inhibits growth, its released by the pituitary gland

Inhibits growth

TSH has different effects on different tissues. TSH causes growth of limbs but degeneration of their tails. Very organ specific.

18
Q

What is protooncogene and oncogene?

A

Protooncogene - is invovled in normal cell growth. Can cause cancer when mutated
Oncogene - when protein oncogen is always active, constant cell growth

19
Q

What are some examples of protooncogenes that can become oncogenes?

A

Ras, Raf, EGFR, MYC and Sno

20
Q

What are tumour suppressors? Give examples

A

Proteins that normally inhibit cell proliferation and growth, but when inactivated leads to cancer formation

p53, Prb, APC, VHL, Patched, RacA and Rac2

21
Q

How do cells grow?

A
  1. cell proliferation
  2. Enlargement
  3. Accretion - matrix deposited between the cells in bone
22
Q

What are the cycclins and Cdks invovled in cell cycle?

A

G1 phase - cyclin D and Cdk4/6
S phase - Cyclin E and Cdk 2

23
Q

What does size of growth come down to?

A

Size of growth comes down to rate of growth and duration

24
Q

What drives the molting process?

A

Ecdysone
Stretch receptors
PTTH