Bio 2 Second Test

Gene expression begins at the ________

promoter

In _______ regulation, a ________ protein binds and prevents transcription.

negative, repressor

In ______ regulation, a _________ protein binds and stimulates transcription.

positive, activator

The ________ is a compound that stimulates the production of inducible proteins

inducer

________ proteins are only produced when needed.

Inducible

When the cell has glucose that needs to be broken down, insulin is produced. Insulin in this case is an example of ___________.

inducible proteins

When it comes to gene regulation, prokaryotes are focused on ________ energy.

conserving

Inducers bind to repressors to make them ________, causing them to _________, causing transcription to _________.

inactive, release, begin

Co-repressors bind to repressors to make them ________, causing them to _______, causing transcription to _________.

active, bind, stop

State the correct order of operons: DNA, _______, _________, ________, DNA

promoter, operator, structural genes

The role of the _______ in operons is to be a site for the RNA Polymerase to bind.

promoter

The role of the _______ in an operon is to be a site for regulatory proteins to bind

operator

Operons contain two or more __________, which are __________.

structual genes, nonregulatory proteins

A ________ is a specific site within a protein allowing it to bind w/ DNA.

structural motif

Two requirements for a structural motif:

1. Fits into the _______ of a DNA helix

2. Amino acids can interact with ______ and/or _______

grooves, bases, backbones

________ proteins are always “on” in a cell

Constitutive

What two structural motifs did we learn about in class?

Zinc finger and helix-turn-helix

The trp operon is a _____ operon.

repressible

The trp repressor protein is produced in its _____ form

inactive

Why does tryptophan acts as the co-repressor in the trp operon?

It binds to the repressor causing transcription to stop.

The lac operon is a(n) ______ operon that _______ lactose

inducible, hydrolyzes

What do the structural genes in the lac operon encode for?

Proteins that hydrolyze lactose and that transport lactose into the cell (permease)

The lac repressor protein is produced in it’s _____ form

active

How does lactose act as the inducer in the lac operon?

When lactose is present it triggers the lac operon

T or F: If glucose and lactose are both absent, there will not be transcription.

True

When glucose and lactose are absent, the repressor is _____ and the cAMP levels are _____.

active, high

Why is cAMP called the cell’s “hunger” molecule?

They tell the CRP when more glucose needs to be produced

T or F: CRP binds near the promoter.

True, it does not bind at the operator

What are two universal recogntion sequences that sigma factors recognize to help RNA polymerase?

-35 element, -10 element

______ factors in prokaryotes = _______ factors in eukaryotes

sigma, transcription

How are genes in eukaryotes similar to operons?

Both have one promoter each

T or F: RNA Polymerase II in eukaryotes only needs one transcription factor to come bind.

False, it needs several

How are transcription factors and inducible proteins similar?

They can both be produced more when the cell needs them

What is the significance of the location of regulatory sequences?

They are not near the promoter

Enhancer sequences are the opposite of _______ sequences.

silencer

Why does the DNA need to bend to change the rate of transcription?

So the regulatory sequences can interact with the RNA polymerase.

What two mechanism does the cell do when it needs to change gene expression without changing the DNA sequence?

DNA methylation, chromatin remodeling

CpG islands can be compared to ______

TATA boxes

Adding a methyl (-CH3) to a cytosine to repress transcription is called what?

DNA methylation