Chapter 14

¡Supera tus tareas y exámenes ahora con Quizwiz!

Negative

--------- control is transcriptional regulation by repressor proteins.

cris, trans

A ------- -effect is mediated by a DNA element that binds regulator proteins, whereas a -------- -effect is mediated by genes that encode diffusible regulatory proteins.

cis-acting

A DNA segment that must be adjacent to the gene that it regulates is known as a(n) ----- - ------ element.

Blank 1: allolactose Blank 2: operator or lacO

A conformational change in the lac repressor protein occurs upon binding of the sugar ------ to it. This change in shape prevents the repressor from binding to the ------- site.

Blank 1: allolactose Blank 2: operator or lacO

A conformational change in the lac repressor protein occurs upon binding of the sugar ------- to it. This change in shape prevents the repressor from binding to the ------- site.

inducer

A small effector molecule that increases the rate of transcription is called a(n) ----------.

operon

A(n) ------- is a cluster of genes that are part of a single transcription unit that is under the control of a single promoter.

CAP site

An activator protein recognizes the ______ of the lac operon.

polycistronic

An mRNA that encodes more than one protein is called ------- mRNA.

inducible

An operon that can be turned on in the presence of a small effector molecule is said to be a(n) ------- operon.

Transcription Post-translation Translation

At what levels does gene regulation occur in prokaryotes?

Regulatory transcription factors

Both positive and negative control

β-galactosidase

Break down of lactose into galactose and glucose

differentiation

Cell ______ is the process by which cells become specialized into particular types.

Lac operator

Cis-acting element

Galactoside transacetylase

Covalent modification of lactose and lactose analogues

Cis-effect

Effect mediated by a cis-acting element

negative, positive

Gene expression can be regulated in two main ways. Repressor proteins are used for ----- control of gene expression, and activator proteins are used for -------- control of gene expression.

When CAP and cAMP bind to the CAP site, this enhances binding of RNA polymerase to the promoter site.

How do CAP and cAMP increase the transcription of the lac operon?

It binds to the repressor protein and prevents it from binding to the operator site of the lac operon.

How does allolactose affect the lac repressor protein?

By only expressing the gene product when it is needed in the cell.

How does gene regulation help conserve energy for an organism?

When lactose is present, the lac repressor protein does not bind to the operator site and transcription can occur. When lactose is present, transcription of the lac operon is high.

How does the presence of lactose in the cell influence the transcription of the lac operon?

only when lactose is present

In E. coli, the genes required to metabolize lactose are expressed ______.

hemoglobin

In mammals, the protein which delivers oxygen to body cells is --------.

operator

In the lac operon, the _______ is the DNA sequence at which the lac repressor binds.

Repressor

Negative control

coordinate the regulation of genes with related functions

Operons enable bacteria to ______

coordinate the regulation of genes with related functions

Operons enable bacteria to ______.

lacY

Permease

encodes more than one protein

Polycistronic mRNA ______.

Activator

Positive control

Activitor

Proteins that bind to DNA and increase the rate of transcription are called -------.

Trans-effect

Regulation by a diffusible factor

regulation of RNA processing

Regulation of prokaryotic gene expression typically involves all of the following mechanisms EXCEPT:

regulation of RNA processing

Regulation of prokaryotic gene expression typically involves all of the following mechanisms EXCEPT: - regulation of RNA processing - regulation of translation - regulation of transcription - modifications to proteins after translation

Promotor

Regulatory transcription factors influence the expression of genes by affecting the rate of transcription. They do so by binding directly to DNA at or near the ------ site.

energy

Some proteins are produced only when needed. This is an example of gene regulation that conserves -------.

inducible

The binding of an effector molecule increases the rate of transcription of the lac operon. Thus, it is said to be a(n) ------- operon.

lacl

The figure is a representation of the lac operon. Match each number to the appropriate gene. 1?

lacZ

The figure is a representation of the lac operon. Match each number to the appropriate gene. 2?

lacA

The figure is a representation of the lac operon. Match each number to the appropriate gene. 4?

lac operon in the absence of lactose

The following diagram shows which type of operon?

to repress transcription of the lac operon

The function of the protein encoded by lacI is ______.

Gene expression

The functional product of genes arises from what process?

lactose

The genes found in the lac operon of E.coli are used for the metabolism of -------.

must be adjacent to the genes that it regulates

The lac operator is an example of a cis-acting element because it ______.

CAP

The lac operon is also under positive control by an activator protein called what?

Inducible operon

The lac operon is an example of what type of operon?

Blank 1: RNA Blank 2: polymerase or pol

The lac repressor protein prevents the transcription of the lac operon genes by the enzyme ------ -------

repressor

The lacI gene encodes the lac -------.

allolactose

The molecule that serves as the inducer of the lac operon is

expression

The process in which the information in a gene is made into a functional gene product, such as an RNA molecule or a protein, is termed gene --------.

Lac repressor

Trans-acting factor

Lactose permease

Transport of lactose across the cell membrane

When the concentration of lactose is low in the cell

Under what conditions does the lac repressor bind to the operator of the lac operon and prevent transcription?

Proteins that bind to DNA and affect the transcription of one or more genes

What are regulatory transcription factors?

lacY Promoter lacZ lacA

What are the basic components of the lac operon?

The transport of lactose across the cell membrane The modification of lactose and lactose analogues The breakdown of lactose

What are the three major functions of the enzymes encoded by the lac operon?

Promoter, operator, and three structural genes

What does the lac operon region contain?

A small effector molecule that increases the rate of transcription

What is an inducer?

A cluster of genes under the transcriptional control of a single promoter

What is an operon?

The process by which cells become specialized in different types

What is cell differentiation?

A small effector molecule involved in the positive control of the lac operon

What is cyclic AMP (cAMP)?

operator

he lacO of the lac operon is the site where the repressor protein binds. It is referred to as the ------.

lacZ

β-galactosidase

i promoter

In this schematic of the lac operon, match each letter to the appropriate DNA element. A?

CAP site

In this schematic of the lac operon, match each letter to the appropriate DNA element. B?

lacP

In this schematic of the lac operon, match each letter to the appropriate DNA element. C?

lacO

In this schematic of the lac operon, match each letter to the appropriate DNA element. D?

repressor

Regulatory transcription factors that bind to DNA and decrease the rate of transcription are termed -------.

lac Y

The figure is a representation of the lac operon. Match each number to the appropriate gene. 3?

operator

The lacO of the lac operon is the site where the repressor protein binds. It is referred to as the ------.

prevent transcription of the lac operon

The protein encoded by the lacI gene functions to:

the lac operator

The transcription of the lac operon genes is inhibited when the lac repressor protein binds to ______.

lac operon in the presence of lactose

This diagram is a representation of which type of operon?

lacA

Transacetylase

positive

Transcriptional regulation by activator proteins is a type of regulation called ------ control.

positive

Transcriptional regulation by activator proteins is a type of regulation called ------- control.

The sequence of nucleotides that is recognized by an activator protein

What is the CAP site for the lac operon?

Bacteria can coordinate the expression of multiple genes in the same biological pathway.

What is the advantage of operon organization in bacteria?

The metabolism of lactose

What is the function of the genes that are expressed in the lac operon of E. coli?

Allolactose

What is the inducer molecule for the lac operon?

They bind to DNA and decrease the rate of transcription.

What is the role of repressor proteins in the regulation of transcription?

Galactoside transacetylase β-galactosidase Lactose permease

What proteins are produced by the three structural genes in the lac operon?

Lactose permease β-galactosidase Galactoside transacetylase

What proteins are produced by the three structural genes in the lac operon?

activator

When ______ proteins bind to DNA, they increase the rate of transcription.

The genes for lactose metabolism are expressed when lactose is present but not when it is absent.

When are the genes involved in lactose metabolism in E. coli expressed and when are they turned off?

transcribe

When geneticists say a gene is "turned on," they mean that it is ------ into mRNA.

When very little or no mRNA is transcribed from the gene

When is a gene "turned off"?

negative

When transcription is regulated by repressor proteins, this is called ______ control.

positive

When transcription of a gene is regulated by activator proteins, the gene is under ______ control.

lacI

Which of the following genes encodes the lac repressor protein?

When allolactose is produced, this causes the transcription of the lac operon.

Why is the lac operon considered inducible?

Hemoglobin

______ is the main protein that delivers oxygen to cells of a mammal's body.


Conjuntos de estudio relacionados

Trivia Murder Party 2 Questions and Answers

View Set

Adolescent Psychology Chapter 8, Psych 21A - Chapter 8, Chapter 8: Identity

View Set

Business Intelligence & Data Warehousing

View Set

NCLEX Review Content Are: Fundamental skills: Fluids & Electrolytes

View Set

Έχουμε Διαγώνισμα (Μάθημα 12)

View Set