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Molecular Biology > Gene Regulation in Prokaryotes > Flashcards

Gene Regulation in Prokaryotes Flashcards

1
Q

What is a Constitutive Gene?

A

Genes that are always expressed and are essential for life

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2
Q

What is a Contingency Gene?

A

Genes that give an advantage under special conditions

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3
Q

What is the effect of gene regulation in Prokaryotes?

A

The production of proteins produced varies in response to the environment

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4
Q

What is the reason for gene regulation in Prokaryotes?

A

To satisfy the needs of the cell but not synthesise wastefully

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5
Q

For prokaryotes the ………………………… is the most important point of control

A

initiation of transcription

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6
Q

What are four ways the cell can regulate gene expression?

A

Transcriptional Control
RNA Processing control
Translational Control
Post-translational Control

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7
Q

What is Coordinate regulation?

A

If regulation of a gene that involves multiple enzymes all or none of the enzymes will be present. These enzymes are all made from the same polycistronic mRNA

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8
Q

In degradative pathways………… is the regulator for gene expression

A

The presence of the substrate regulates whether or not the catabolic enzymes are produced

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9
Q

In biosynthetic pathways………….. is the regulator for gene expression

A

The presence of the final product regulates the production of the enzymes needed

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10
Q

What is an operon?

A

A group of genes adjacent to each other on the chromosome that are transcribed from a single promoter into a single mRNA molecule.

ONLY IN PROKARYOTES

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11
Q

What is the Tryptophan Operon

A

The operon that is responsible for the production of enzymes used to synthesise Trp

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12
Q

When there is no Trp what happens?

A

The operon is switch on

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13
Q

When there is excess Trp what happens?

A

The operon is switched off

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14
Q

In the regulation of it’s operon Trp acts as a……………

A

Co-repressor

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15
Q

What is the Lac Operon?

A

The operon responsible for the transport and metabolism of lactose in E. Coli

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16
Q

What is E. Coli’s preffered source of energy?

A

Glucose

17
Q

E. Coli will consume glucose until it is all gone. Then the cell will temporarily stop…………… Then the ……………….. is switched on and …………….. is used for energy and the cell continues to grow

A

Growing, then the lac operon is switched on and lactose is used for energy

18
Q

What enzymes are for lactose metabolism in E. Coli?

A

Lactose Permease and B-Galactosidase

19
Q

What is an Inducer?

A

A small molecule that induces the production of an inducible protein

20
Q

What does B-Galactosidase do?

A

It catalyses the hydrolysis of galactose into lactose. It also catalyses the reaction that converts lactose into Allolactose which is an inducer for B-Galactosidase synthesis.

21
Q

In the lac operon the main operator is …………………. to the promoter

A

Directly adjacent

22
Q

The I gene is ………… of the lac operon. It is transcribed using it’s own……………. and is ……………… separately to give the repressor protein

A

upstream

promoter

translated

23
Q

When the inducer for the lac operon is present, the enzymes are …………. and the genes are switched ……..

A

needed and the genes are switched on

24
Q

How does the lac repressor work?

A

It binds to 2 out of 3 identical binding sites on the DNA and forms a DNA loop with prevents transcription by preventing the RNA Polymerase from accessing the DNA

25
Q

When there is no inducer Lactose in the cell the lac operon is switched………

A

off

26
Q

When there is inducer Lactose in the cell the lac operon is switched…….

A

on

27
Q

The lac promoter is considered to be a relatively …….. promoter meaning RNA polymerase recognises it …………

A

Weak promoter, recognizes it poorly

28
Q

For the lac operon, ………… is needed to help RNA polymerase bind to the promoter

A

and activator protein called CAP

29
Q

…………. must bind to cAMP before it can bind to the promoter region

A

CAP

30
Q

What is the function of positive regulation of the lac operon

A

Glucose is the preferred sugar so when it is present the operon is switched off

It allows the cell to sense when glucose is not present

31
Q

If [Glucose] decreases then the [cAMP] …………….

A

increases

32
Q

If [Glucose] increases then the [cAMP] …………….

A

decreases

33
Q

When levels of cAMP rise, levels of the cAMP-CAP dimer ……………..

A

Rise

34
Q

What makes the positive regulation of the lac operon positive?

A

There is an activator not a repressor

Molecular Biology (3 decks)

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