Gene Expression

Question 1

Human fingers are originally webbed when they first develop. How does the body create individual fingers from this webbed structure?

Answer 1

The cells of the webbing undergo apoptosis: they shrink in size, their nuclear DNA is degraded, and they separate into small, membrane-wrapped fragments. Finally, nearby phagocytic cells engulf these pieces.

Question 2

Defined as programmed cell death

Answer 2

Apoptosis is defined as programmed cell death, by which a damaged cell initiates an intracellular cascade resulting in destruction of the cell.

Question 3

Genetic system used by prokaryotes to regulate expression of specific genes

Answer 3

Operon

Question 4

Positive control operon

Answer 4

Gene expressed when an activator is present (prok)

Question 5

Negative control operon

Answer 5

Genes expressed unless repressor is present (prok)

Question 6

True or False: The lac and trp operons are both negatively controlled operons

Answer 6

True, both are under negative

Question 7

What are the subtypes of negative operons?

Answer 7

Inducible and Repressible

Question 8

This type of operon requires an activator

Answer 8

positively controlled gene

Question 9

This type of operon requires a repressor

Answer 9

negatively controlled gene

Question 10

Specific operon whose normal position is the off position

Answer 10

Lac operon which is a negative inducible

Question 11

Specific operon whose default is the on position

Answer 11

trp operon which is negative repressible

Question 12

True or False: the lac operon is under negative inducible control as well as positive control

Answer 12

True

Question 13

What are the components to the Lac operon?

Answer 13

The lac operon has a

• promoter site
• CAP binding site
• operator
• LAC Z,Y,A

Question 14

Describe how the Lac operon works

Answer 14

The lac operon is influenced by both negative and positive control. The operon possesses genes that help with lactose metabolism. The preferred sugar is glucose but when glucose is not as available, the prokaryote has means of metabolizing lactose which is where the lac operon comes into play.
In terms of NEGATIVE control, it is an INDUCIBLE negative operon. THe repressor is normally bound to the operator until ALLOLACTOSE binds to the repressor releasing it from the site.
In terms of POSITIVE control, there is the CAP binding site. WHen clucose is low, cAMP is high. cAMP binds to CAP (catabolyte activator protein) which binds to the CAP binding site which helps increase transcription

Question 15

True or False: When lactose levels are low and glucose levels are high, the repressor is not bound to the lac operon

Answer 15

False, it is bound

Question 16

True or False: when tryptophan is abundant, the trp operon is turned off

Answer 16

true

Question 17

True or False: tryptophan exhibits positive control on its operon

Answer 17

false, negative

Question 18

Short sequence upstream of its target gene that contains a TATA box

Answer 18

Eukaryotic promoter sequence

Question 19

Proteins that recruit RNA polymerase

Answer 19

Mediator porteins

Question 20

Proteins that bind to pseific DNA sequences to regulate gene expression

Answer 20

Transcription factors

Question 21

Enhancer

Answer 21

EUKS! sequences that promote expression, can be upstream or downstream. Activators bind to them. Enhancer region gets close to promoter sequence by a DNA hairpin loop to facilitate the imitation of transcription

Question 22

Silencer

Answer 22

EUKS! Repressor binds to these

Question 23

Acetylation

Answer 23

Helps make DNA more accessible for transcription by masking positive charges on histones

Question 24

Deacetylation

Answer 24

Promote tighter packing of DNA

Question 25

Methylation

Answer 25

Methyl group added to cytosine or adening nucleotides in DNA. It silences gene sequences. Plays a role in epigenetics

Question 26

Heritable changes that affect gene expression with out directly changing the sequences itself

Answer 26

Epigenetics

Question 27

siRNA

Answer 27

small interfering is double stranded

Question 28

microRNA

Answer 28

single stranded

Question 29

RISC

Answer 29

RNA induced silencing complex

Question 30

An individual is experiencing symptoms related to the lack of a specific protein. However, genetic analysis finds no mutation in the gene encoding this protein. If a mutation does indeed exist, it would most likely be found:

Answer 30

A mutation in the promoter sequence would prevent initiation of transcription entirely, resulting in a total lack of the relevant protein.