Cell biology 8S.2

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extracellular stimuli
growth factors, mitogens and survival factors
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do neurones divide?
no!
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do liver cells divide?
not normally, but can if the liver is damaged
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Mitogens
stimulate cell division by triggering a wave of G1/S- cdk activity
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Growth factors
Stimulate cell growth (cell mass) by promoting synthesis of proteins and inhibiting proteolysis
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Survival factors
promote cell survival by supressing the form of programmed cell death called apoptosis
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What is a mitogen?
a molecule that induces an effect when it reaches a receptor
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Critical features of cell cycle
avaliable building blocks, complete copy of dna, correct attachment of chromosomes to spindles
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cyclins
produced and destroyed according to phase of cell cycle
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Cdk's
acquire kinase enzyme activity when cyclins bind. 'cyclin dependant kinase'
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Phosphate modified target proteins
execute the appropriate process in the cell cycle progression
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G1/S cyclins
activate Cdk's in late G1 and trigger the progression through START, resulting in a commitment to cell cycle entry.
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S-cyclins
activate Cdk's soon after the progression through START and help stimulate chromosome duplication
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M-cyclins
activate Cdk's that stimulate entry into mitosis at the G2-M transition
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How are cyclins/ Cdk's inhibited
phosphorylation, binding to inhibitary protein, proteolysis
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What does activation of MAP kinase by mitogens do?
lead to the induction of Myc and hence G1-Cdk complex
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What does activation of G1-Cdk do?
promotes cell cycle entry
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p53 induced transcription of p21
arrests the cell cycle by inhibiting Cdks
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How are some cells limited in terms of replication?
the telemeres shorten until DNA is revealed and damage occurs
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Give an example of a cell where telemeres always grow back
cancer cells
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what haults the cell cycle entry?
non-proliferating cell and proliferating cell
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can cell growth occur without division?
yes, shown in muscles which can be in permanant cell arrest
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Who discovered the nerve growth factor?
Rita, Jewish in WW2
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3 types of stem cells
adult, embryonic and induced pluripotent
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Other cards in this set

Card 2

Front

do neurones divide?

Back

no!

Card 3

Front

do liver cells divide?

Back

Preview of the front of card 3

Card 4

Front

Mitogens

Back

Preview of the front of card 4

Card 5

Front

Growth factors

Back

Preview of the front of card 5
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