T3M2

Question 1

Operon end goal

Answer 1

the ability to express genes together, expressed as one big long mRNA sequence (polycistronic)

Question 2

Polycistronic mRNA

Answer 2

a molecule that contains more than one protein encoding segment

Question 3

Lactose operon is negatively regulated - negative cue

Answer 3

glucose is in the environment

Question 4

cAMP levels will be ____ when glucose levels are high

Answer 4

low

Question 5

What is cAMP?

Answer 5

a signaling molecule, more positive regulation of the lac operon, enhance gene operation, made from ATP

Question 6

When glucose levels are low cAMP levels will be

Answer 6

high

Question 7

CRP-cyclic AMP complex facilitates

Answer 7

the ability of RNA polymerase to bind to the lac promoter

Question 8

More cAMP=

Answer 8

more positive regulation and less glucose!!

Question 9

High glucose=

Answer 9

less cAMP, not binding as much to enhancer site

Question 10

Is the lac operon ever fully off?

Answer 10

No, if it was fully off, 0 lac permease, run out of glucose and there is no cue for lactose to get in.

Question 11

As E. coli cells transition from glucose to lactose
metabolism, there is a concomitant increase in

Answer 11

the amount of detectable beta-galactosidase and lactose permease proteins

Question 12

beta-galactosidase and lactose permease proteins are not expressed until

Answer 12

glucose is fully depleted from the growth medium

Question 13

lactose permease is

Answer 13

a transport protein that sits in the bacterial cell membrane and allows for the transport of lactose into the bacterial cells

Question 14

The beta-galactosidase protein is

Answer 14

the cytoplasmically situated bacterial enzyme that cleaves the imported lactose into glucose and galactose

Question 15

A key advantage to the organization of the prokaryotic genome is

Answer 15

groups of related genes with similar functions
can often be found clustered together into
operons - ability to control the transcription of the whole gene cluster as one unit

Question 16

Each gene has its own promoter and enhancers

Answer 16

eukaryotes

Question 17

Model for prokaryotic gene expression discovered by

Answer 17

Francois Jacob and Jacques Monod (1961)

Question 18

In bacteria, groups of functionally related genes are organized into

Answer 18

transcriptional units along the bacterial
chromosome

Question 19

Bacteria, gene clusters are controlled by

Answer 19

a single on/off switch that can control the transcription of the clustered genes mediated by an operon

Question 20

The bacterial operon consists of

Answer 20

a promoter, an operator (or on-off switch), and the coordinated gene cluster whose products will function in a common pathway or cellular response

Question 21

An operator is

Answer 21

a sequence of nucleotides near the start of the operon that can be regulated to allow or inhibit transcription

Question 22

When the operator is not bound to any
transcriptional inhibitor

Answer 22

RNA polymerase can attach to the promoter and transcribe the genes in the operon

Question 23

transcription in bacteria can give rise to

Answer 23

one long mRNA molecule (or polycistronic mRNA) that can code for many protein

Question 24

During translation, bacterial cells can then produce separate polypeptides because

Answer 24

the polycistronic mRNA is punctuated with start and stop codons that signal where the coding sequence for each polypeptide begins and ends

Question 25

The lac operon is

Answer 25

a model for transcriptional regulation in prokaryotes

Question 26

The regulation of beta-galactosidase and lactose permease expression is under the control of

Answer 26

The lac operon in E. coli cells

Question 27

Regulatory sequences of transcription that exist within the lac operon

Answer 27

• The promoter that binds the RNA polymerase
  complex
• The operator (lacO) which is the binding site for a repressor protein that is expressed by the lacI coding sequence

Question 28

Two main structural genes
code for the primary proteins that are needed to facilitate lactose metabolism

Answer 28

• The lacY gene which codes for a lactose permease transport protein which will embed itself in the cell membrane and allow for the import of lactose into the bacterial cell
• The lacZ gene which codes for B-galactosidase that will be able to cleave the disaccharide lactose into glucose and galactose

Question 29

RNA polymerase can simply bind to and
activate

Answer 29

The transcription of the lacZ and lacY
genes

Question 30

the lac l gene controls

Answer 30

the expression of the lacZ and lacY genes

Question 31

lacl is the gene that codes for

Answer 31

a repressor protein which can bind to the operator and inhibit transcription from occurring

Question 32

The ability of a repressor protein to halt transcription in this manner is often identified as

Answer 32

negative transcriptional regulation

Question 33

Negatively regulated transcription process

Answer 33

a repressor protein will bind to the operator region of the operon, and this will result in turning off transcription since the RNA polymerase is no longer able to bind to the promoter region of the operon

Question 34

Lactose operon regulation

Answer 34

negative

Question 35

The lac operon repressor once expressed by the
lac l gene is able to inhibit

Answer 35

the expression of the beta-galactosidase and the lactose permease proteins

Question 36

Indicator for the general nutritional state of
E. coli cells

Answer 36

concentration of cAMP in the bacterial cell

Question 37

When glucose levels are high in the environment surrounding bacterial cells, there is

Answer 37

an inhibition of the enzyme adenylyl cyclase,
which catalyzes the production of cAMP from
ATP (low levels of intracellular
cAMP)

Question 38

High extracellular glucose concentration

Answer 38

• inhibition on adenylyl cyclase enzyme
• low levels cAMP
• CRP-cAMP complex will not bind lac operon
• lower levels of transcription

Question 39

What can bind to repressor proteins and prevent their binding to the DNA?

Answer 39

Inducer proteins