Control Of Gene Expression Flashcards

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1
Q

Every cell contains the same gene. So how do cells work in different ways?

A

Although they all contain the genes, only certain genes are expressed in any cell at one time

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2
Q

Why do differentiated cells differ from each other?

A

They produce different proteins coded by the genes that are expressed in that cell

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3
Q

What is a totipotent cell?

A

Cells that can mature into any body cell

Such as fertilised eggs

During the process of cell specialisation only some genes are expressed so only some of the DNA is translated into proteins. Therefore only making proteins required to carry out specific jobs

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4
Q

How are genes prevented from expressing themselves?

A

Transcription is prevented, preventing the production of mRNA

Break down mRNA before it is translated

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5
Q

What are stem cells?

A

Undifferentiated dividing cells found in adult tissue and need to be constantly replaced

Found in the small intestines, skin and bone marrow

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6
Q

What are transcriptional factors?

A

Specific molecules that move from the cytoplasm into the nucleus

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7
Q

How do transcriptional factors regulate transcription?

A

The factor binds to a specific region of DNA stimulating it to begin the process of transcription

mRNA is produced and the genetic code is translated into a polypeptide

When a gene isn’t expressed the site on the factor is blocked by an inhibitor preventing transcription

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8
Q

Why is oestrogen a good molecule for switching on a gene?

A

It’s lipid soluble and so easily diffuses through the phospholipid bilayer

Combines to a site on a receptor as complimentary

Oestrogen changes the shape and so releases the inhibitor so DNA can bind to the transcriptional factor

Transcriptional factor moves into nucleus

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9
Q

The effect of siRNA

A

Prevents gene expression by breaking down mRNA before it is translated

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10
Q

How is siRNA used?

A

An enzyme cuts double stranded RNA into siRNA

Some of the siRNA combines with an enzyme

The siRNA guides the enzyme to a mRNA by pairing it’s bases with complementary sections of the mRNA

Enzyme cuts the mRNA into smaller sections
mRNA can no longer translate it

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11
Q

What are some possible uses for siRNA

A

Used to identify the role of genes in a biological pathway. siRNA that blocks a particular gene can be added to a cell and determine from the effects what role the blocked gene is

Use siRNA to block genes causing diseases

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