Gene expression and regulation

Question 1

What is the gene regulation ?

Answer 1

A mechanisms for controlling which genes get expressed and at what levels.

Question 2

Where gen e regulation occurs?

Answer 2

At the level of transcription or production of mRNA

Question 3

In bacteria, gene are _____ on the chromosome?

Answer 3

Clustered

Question 4

Gene are transcribed by a ?

Answer 4

One promoter as a single unit.

Question 5

Promoter

Answer 5

RNA Polymerase binding site. It’s a control sequence

Question 6

Whta are control sequences ?

Answer 6

Are stretches of DNA that coordinate

gene expression.

Question 7

Operon

Answer 7

Is a cluster of genes with related

functions under the control of a single promoter.

Question 8

Operator

Answer 8

is a DNA sequence between the promoter and the genes they regulate. Switcher for the genes

Question 9

Operons are made of

Answer 9

Coding sequences of genes, Regulatory DNA sequences, Regulatory proteins

Question 10

Regulatory DNA sequences are

Answer 10

binding sites for regulatory proteins

Question 11

Repressors are

Answer 11

regulatory proteins that binds to pieces of DNA called operators and blocks transcription

Question 12

Activators are

Answer 12

regulatory proteins that is bound to its DNA binding site (upstream of the promoter) and increase transcription.

Question 13

When an operon is said to be Inducible

Answer 13

When is off but can be turned on by a small molecule called inducer

Question 14

When an operon is said to be repressible

Answer 14

When is on but can be turned off by a small molecule call corepressor.

Question 15

How are levels of lactose and glucose detected

Answer 15

thanks to 2 regulatory proteins: lac repressor and CAP

Question 16

What is the lac repressor?

Answer 16

a regulatory protein that the E.coli uses to regulate the production of B Galactosidase.. It is encoded by LacI, not in the operon.

Question 17

Which gene encodes for the B Galactosidase

Answer 17

Laz Z Gene

Question 18

What is the B Galactosidase and what it does

Answer 18

an enzyme responsible for splitting down the lactose in its monosaccharides

Question 19

What can bind the repressor?

Answer 19

Allolactose, a molecule that prevent the repressor to bind the operator

Question 20

What is CAP

Answer 20

An activator protein that binds cAMP

Question 21

How CAP is regulated

Answer 21

CAP is regulated by cAMP, a signal made by E.coli when glucose levels are low.

Question 22

How tryptophan is made by E.coli

Answer 22

E.coli can make its own tryptophan with enzymes encoded by 5 genes. –> Tryptophan synthetase

Question 23

What the operator of the trp operon binds?

Answer 23

trp repressor

Question 24

By which gene the trp repressor is made

Answer 24

trpR

Question 25

What does the corepressor

Answer 25

The tryptophan (corepressor) switches the repressor in its active state.

Question 26

What happens when we have low tryptophan in the organism?

Answer 26

trp repressor is not bound to tryptophan (since there is no tryptophan) and become inactive. RNA Polymerase can start

Question 27

What happens when we have high tryptophan in the organism?

Answer 27

Tryptophan binds the repressor and causes it to change shape. the repressor binds the operator and blocks the RNA Polymerase.

Question 28

What can regulate eukaryotic gene regulation?

Answer 28

Regulatory sequences that bound regulatory elements?

Question 29

What do regulatory elements bind?

Answer 29

Transcription Factors

Question 30

Where is the transcription localize?

Answer 30

In the Nucleus

Question 31

What are the Introns

Answer 31

Non coding sequences of DNA

Question 32

What is the TATA Box?

Answer 32

A TATA box is a DNA sequence that indicates where a genetic sequence can be read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins.Proteins called transcription factors can bind to the TATA box and recruit an enzyme called RNA polymerase, which synthesizes RNA from DNA.

Question 33

Which are the histone acetylation mechanisms in gene regulation^?

Answer 33

Histone acetylation further attract activator proteins and Histone acetylation directly attract TFs

Question 34

What are Micro RNAs

Answer 34

They are a family of small RNAs. They are products of a new type of RNA. They are not translated into proteins. They are just genes. Non-coding sequences.

Question 35

What do miRNAS do?

Answer 35

They regulate gene activity in the cytoplasm, by binding to messenger RNA molecules. This causes the mRNA to be untranslatable, or to be degraded. They regulate other genes by binding to complementary sequences in the target gene.

Question 36

Why miRNA are important?

Answer 36

They act in multiple biological events: Developmental timing, Differentiation, Aging, Apoptosis, Cancer, Cell Cycle..

Question 37

What is the epigenetic?

Answer 37

Epigenetics is the study of inherited changes caused by mechanisms other than changes in the DNA sequence.

Question 38

What Does the methylation of cytosines in epigenetic mechanisms?

Answer 38

The methylation of C’s near the promoter region of gene prevents transcription.