Why don't all cells complete every funtion they have the genes for?
Because only certain genes are expressed (switched on) in any one cell at any one time
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What is a protein coded from?
Genes it contains that are expressed, these then tell the cell which protein to produce
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What are 'Totipotent cells?'
Cells that can mature into any body cell - unspecialised
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What are 'Totipotent cells' called in mature animals?
Adult stem cells
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Where are adult stem cells found?
Inner lining of the small intestine, in the skin and in the bone marrow
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What needs to happen for 'Transcription' to begin?
The gene needs to be stimulated by specific molecules that move from the cytoplasm into the nucleus, the molecules are called transcriptional molecules
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What does each 'Transcriptional factor' have?
A site that binds to a specific region of the DNA in the nucleus
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What happens when a gene is not being expressed?
The site on the transcriptional factor that binds to DNA is blocked by an inhibitor molecule
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What does the inhibitor molecule do?
Prevents the transcriptional factor binding to DNA and so prevents transcription and polypeptide synthesis
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What does it mean when Oestrogen is a 'lipid soluble molecule?'
That it can diffuse easily through the phospholipid portion of cell-surface membranes
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What does Oestrogen do once it is inside the cytoplasm?
It combines with the site on a receptor molecule of the transcriptional factor
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What does Oestrogen do once it has combined with the binding cite
It changes the shape of the receptor molecule, this releases the inhibitor molecule from the DNA binding site on the transcriptional factor which can now enter the nucleus
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What happens once the transcriptional factor moves into the nucleus?
The combination of the transcriptional factor with DNA stimulates transcription of the gene that makes up the portion of DNA
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How can 'Gene expression' be prevented?
By breaking down messenger RNA before its genetic control can be translated into a polypeptide
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What does siRNA stand for?
Small interfering RNA
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What is siRNA?
When an enzyme cuts large double-stranded molecules of RNA into smaller sections
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What does siRNA combined to?
An enzyme
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What does the siRNA do to the enzyme?
Guides the enzymes to a messenger RNA molecule by pairing up the bases with the complementary ones on a section of the mRNA molecule
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What is an advantage of siRNA cutting up DNA?
It can be used to block genes that cause diseases
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Other cards in this set
Card 2
Front
Why don't all cells complete every funtion they have the genes for?
Back
Because only certain genes are expressed (switched on) in any one cell at any one time
Card 3
Front
What is a protein coded from?
Back
Card 4
Front
What are 'Totipotent cells?'
Back
Card 5
Front
What are 'Totipotent cells' called in mature animals?
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