BIOL211 - L13

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  • Created by: Katherine
  • Created on: 12-04-17 10:24
What is cell cycle control?
An ordered system of biochemical switches that is regulated and driven by cyclin/CDK activities. The system has the ability to respond to extra-and intrcellular signals/stimuli and to determine whether cells enter and process though the cell division
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What are the main events of the eukaryotic cell cycle?
Single chromosome goes through G1. DNA synthesis in S phase. Mitosis occurs next (chomosome condensation, you break down the nuclear envelope, chromosomes segregate (the cell has to know that all the chromosomes have separated).
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What is the centrosome?
It is the little structure which the spindle is built upon. It duplicates in parallel to replication.
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What is the problem in understanding?
The cell needs to establish co-ordination between different events occuring in space and time.
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What are the main drivers of the cell cycle process?
Cyclin Dependent Kinases
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How was the G2/M transition monitoerd?
Experimental system: eggs and early embryos of amphibians and marine invertebrates.
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What do we need if we want an experimental system?
High protein content, readily available in high number and therefore easy to work with. Naturally synchronized cells (arrested at a specific point in the cell cycle) You need to be able to trigger cell cycle division.
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What do Cyclin CDKs do?
These heterodimeric kinases regulate the activities of multiple proteins involved in entry into the cell cycle, DNA replication and mitosis by phosphorylating them at specific regulatory sites and activating some and inhibiting others to coordinate.
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What is the process of frog oocyte maturation?
G2 arrested oocyte. With added progesterone you go into Meiosis I (metaphase). After a meiotic interphase the egg is arrested in meiosis II. You can then fertilise the egg to get synchronous divisions.
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What is maturation promoting factor?
There is some factor within the cells that drive the process.
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How do you do an assay?
You take cytoplasmic extract at any point and see whether it will drive the maturation event or not. So you can follow the MPF activity in time
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How was cyclin identified?
Set up as a student prac, they took frog oocytes, arrested them and fertilised them (in the presence of radioactive methionine) All protein should be labelled by this. They took protein extracts post fertilisation.
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Cyclin accumulation, immediately preceeds...
Mitosis
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What happens if you add mRNA encoding with wild type cyclin B to tubulin?
You see mitotis going on
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Cyclin is a consituent of...
MPF
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At which point of the cell cycle is Cyclin B con highest?
It peaks during the cell cycle and then dramatically drops.
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We think that Cyclin B is a component of MPF, but is it the entire activity?
It isn't (next lecture)
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Cyclin degradation is required for...
Mitotic exit
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What happens ifyou added back a non degradable cyclin B mRNA?
The mRNA was made by a 5' deletion which directs the synthesis of an N terminally truncated protein - it was stuck in mitosis.
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Was the truncated protein degradable?
No - there was something about the N terminal truncated section which stops it from degrading.
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Where do you need cyclin B and where do you not want it?
You need cyclin B to get into mitosis and you have to degrade it to get out of mitosis.
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Card 2

Front

What are the main events of the eukaryotic cell cycle?

Back

Single chromosome goes through G1. DNA synthesis in S phase. Mitosis occurs next (chomosome condensation, you break down the nuclear envelope, chromosomes segregate (the cell has to know that all the chromosomes have separated).

Card 3

Front

What is the centrosome?

Back

Preview of the front of card 3

Card 4

Front

What is the problem in understanding?

Back

Preview of the front of card 4

Card 5

Front

What are the main drivers of the cell cycle process?

Back

Preview of the front of card 5
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