Micro bio 205A chp 7

What is the proper order of the following events in the expression of a eukaryotic gene?1. translation2. RNA processing3. transcription Multiple choice question. 3, 1, 2 1, 3, 2 1, 2, 3 2, 3, 1 3, 2, 1

3,2,1

Which of the following statements about RNA interference are TRUE? Multiple select question. A short strand of DNA complementary to RNAi binds to a RISC unit, leading to destruction of that DNA. A short strand of RNA within a RISC unit attaches to a complementary sequence of mRNA, inducing transcription. A short strand of RNA within a RISC unit hybridizes to a complementary sequence of mRNA. Binding of RNA in the RISC to complementary mRNA leads to enzymatic destruction of that mRNA.

A short strand of RNA within a RISC unit hybridizes to a complementary sequence of mRNA. Binding of RNA in the RISC to complementary mRNA leads to enzymatic destruction of that mRNA.

When analyzing a DNA sequence, the sequence_________ , on the plus strand indicates the possible start codon AUG in an RNA transcript.

ATG

why do carbon catabolite repression block the production or enzymes needed t metabolize a different carbon source?

CCR make sure that glucose is used . - The CCR mechanisms make sure that the cells use and metabolize sugar which allows them to grow fast.

If both glucose and lactose are present in a medium, why is the lac operon not transcribed? Multiple choice question. When glucose and lactose are both present, the cell does not have sufficient ATP to activate the operon. Cells preferentially use lactose, but the glucose acts as a repressor when present. Cells preferentially use glucose and only use lactose if the glucose is depleted. Cells get confused by the simultaneous presence of both carbohydrate sources.

Cells preferentially use glucose and only use lactose if the glucose is depleted.

True or false: DNA-binding proteins that bind to DNA always inhibit transcription. True false question.True or False

False

Metagenomics is the analysis of ______. Multiple choice question. proteins produced by all microbes in a population a specific microbial genome within a mixed population of microbes proteins and total microbial genomes in an environment total microbial genomes in an environment proteins produced by a specific microbe within a mixed population of microbes

Is the analysis of total microbial genomes in an environment.

What happens to the repressor of the lac operon when lactose is not available? Multiple choice question. It is functional and cannot bind to the operator. It is functional and can bind to the operator. It is nonfunctional and cannot bind to the operator. It is functional and can bind to the promoter. It is nonfunctional and can bind to the operator.

It is functional and can bind to the operator.

Eukaryotic cells can regulate the levels of mRNA by destroying specific RNA transcripts through a process known as ____________RNA , abbreviated RNAi.

RNA interference

In carbon catabolite repression, CAP functions as a(n) ____, while cAMP functions as a(n) _____. Multiple choice question. activator; inducer start codon; stop codon inducer; activator promoter; terminator initiator; terminator

activator; inducer

Processing or mRNA includes adding about 200 _____ residues to the _____.

adenine; 3' end

Carbon catabolite repression is a regulatory mechanism that ensures that a cell ______. Multiple choice question. imports and uses the sugar that allows fastest cell growth only imports and uses glucose from a medium can mutate so that is can use any carbon source for growth imports and uses lactose if it is present in the medium

ans: imports and uses the sugar that allows fastest cell growth The uptake and degradation of sugars by a cell are often controlled by carbon catabolite repression CCR, a regulatory mechanism in which a carbon compound prevents the production of inducible enzymes needed for the metabolism of different carbon source. This mechanism makes sure cells grab and metabolizes the sugar that help the cell to grow "fast". this can be shown with a slide of E.coli growing cells that include sugar and lactose

Some microorganisms can alter characteristics of certain surface proteins, allowing them to avoid detection by the host's immune system. This phenomenon is called ______. Multiple choice question. antigenic variation natural selection quorum sensing phase variation

antigenic variation

Microorganisms must adapt rapidly to changes in their environment in order to ______. Multiple choice question. survive communicate die infect

survive

anabolism

synthesizes and assembles the subunit of macromolecules using the ATP

In a carbon catabolite repression (CCR) regulatory mechanism called inducer exclusion, ______. Multiple choice question. the lactose transporter protein is induced and lactose is taken up by the cell the inducer molecule is locked, preventing a permease from functioning the lactose transporter protein is locked in a non-functional position, preventing the cell from taking up lactose the glucose transporter protein is locked, preventing the cell from taking in glucose

the lactose transporter protein is locked in a non-functional position, preventing the cell from taking up lactose

Alternative sigma factors allow cells to directly control ______. Multiple choice question. transcription translation replication

transcription

Information is passed from the environment into the cell by a process known as signal

transduction

Exoenzymes

transported extracellularly, where they break down large food molecules or harmful chemicals. example is organic compounds such as protein are broken down into their subunits. The resulting subunits are transported into the cell and further degraded to form appropriate prescures metabolites.

This diagram shows a mechanism by which bacteria can detect and react to changes in their external environment. This mechanism is called a

two component regulatory system

DNA sequences is represented by ______ strand. The nucleotide sequence of the corresponding RNA transcript is _______.

+; +

The absence of a polyA tail will most likely do what to a eukaryotic mRNA? Multiple select question. 1. reduce the efficiency of its translation 2. reduce its stability 3. reduce the efficiency of its transcription 4.reduce the efficiency of its splicing

-.reduce the efficiency of its translation -.reduce its stability

enzymes involved in anabolic reaction

1. DNA polymerase - generates DNA 2. RNA polymerase- generates RNA 3. APT synthase generates ATP not correct: ? why 1.amylase- converts starch to glucose 2.lipase-converts fats to fatty acids and alcohols

DNA-binding proteins that bind to DNA always inhibit transcription. True false and why?

Reason: This is false. DNA-binding proteins can act as repressors (inhibit transcription) or activators (facilitate transcription).

destruction of RNA

The short RNA strand does this by binding to complementary sequences on an mRNA molecule tagging that transcript for destruction by enzymes in the RISC.

lac operon

a gene system whose operator gene and three structural genes control lactose metabolism in E. coli

CAP is? repressor activator

activator

Select all that apply The absence of a polyA tail will most likely do what to a eukaryotic mRNA? Multiple select question. 1.reduce the efficiency of its transcription 2.reduce the efficiency of its splicing 3.reduce the efficiency of its translation 4.reduce its stability

3.reduce the efficiency of its translation 4.reduce its stability

Enzymes that are usually synthesized but are not made when they are not needed are ______ enzymes. 1. repressible 2. inducible 3. repressible

3.repressible the reason these are not correct: constitutive Reason: Recall that constitutive enzymes are made all of the time. whereas inducible Reason: Recall that inducible enzymes are synthesized only when needed.

Quorum sensing can best be described as the ability of microorganisms to _______. Multiple choice question. 1. form biofilms and coordinate the infection process 2. synthesize signaling molecules to help them move in the environment 3. survive in adverse conditions by communicating with each other 4. detect the density of cells within their own population

4. detect the density of cells within their own population

The eukaryotic ribosome is 80S. It is composed of a small subunit which is _____________and a large subunit which is ________.

40s; 60s

Segments of the precursor mRNA in eukaryotes that are noncoding are called ______. Multiple choice question. prions introns exons integron

intron

n eukaryotes, the ribosome found in the cytoplasm is best described as _______. Multiple choice question. 30S + 50S = 70S 30S + 50S = 80S 40S + 60S = 80S 20S + 50S = 70S

40S + 60S = 80S

In the transcriptional regulatory mechanism called repression, the repressor protein can only bind the operator if a molecule called a(n) ______-forms a complex with the repressor.

?

If both glucose and lactose are present in a medium, why is the lac operon not transcribed? Multiple choice question. Cells preferentially use glucose and only use lactose if the glucose is depleted. Cells get confused by the simultaneous presence of both carbohydrate sources. When glucose and lactose are both present, the cell does not have sufficient ATP to activate the operon. Cells preferentially use lactose, but the glucose acts as a repressor when present.

Cells preferentially use glucose and only use lactose if the glucose is depleted.

______ enzymes are usually not synthesized but are made when they are needed by a cell.

Inducible

True or false: Repressible enzymes are essential enzymes that are constantly synthesized and are involved in processes such as glycolysis. True false

This is false. Repressible enzymes are usually produced but are switched off when not needed.

Which of these is typically involved in a two-component regulatory system? Multiple choice question. an activator protein and a response regulator a repressor protein and an activator protein a membrane-spanning sensor and an activator protein a membrane-spanning sensor and a response regulator a repressor protein and an inducer

a membrane-spanning sensor and a response regulator

An important mechanism that cells use to detect and react to changes in the external environment is called _______. Multiple choice question. a two-component regulatory system a multi-locus detection and reaction system

a two-component regulatory system

A(n) ____________is a regulatory protein that facilitates transcription by enhancing the ability of RNA polymerase to initiate transcription.

activator

what is the purpose of the activator in transcription?

activator is protein that facilitates transcription (positive regulation). genes controlled by an ineffective promoter preceded by an activator-binding site.

Consider regulation of the lac operon in E. coli. In the presence of lactose, the repressor no longer binds to the ______ and transcription ______ if glucose is not present. Multiple choice question. promoter; stops operator; proceeds promoter; proceeds operator; stops

ans: operator; proceeds reason: when lactose is in the cell some of it is converted to allolactose, an (inducer)in doing so the compound binds to repressor and changes the repressors shape so that it can no longer bind to the operator.with the operator unoccupied RNA polymerase can begin transcribing the operon. however, when lactose is not available in the repressor binds the operator, blocking RNA polymerase.

select all that apply: The two types of RNA used in RNA interference (RNAi) are ______. Multiple select question. a.interfering RNA (iRNA) b.microRNA (miRNA) c.messenger RNA (mRNA) d.transfer RNA (tRNA) e.short interfering RNA (siRNA)

b. microRNA (miRNA) e. short interfering RNA (siRNA)

A new field has emerged which employs the power of computers to store, retrieve, and analyze DNA sequence data called ______. Multiple choice question. bioinformatics bioethics information technology computer technology

bioinformatics

In the presence of lactose, the lac repressor is _______ to allolactose and so ______ to the operator. Multiple choice question. not bound; can bind not bound; cannot bind bound; cannot bind bound; can bind

bound; cannot bind

catabolism

breaks down macromolecules into subunits (exergonic reaction) releasing energy for the cell

additionally for activator CAP to do its transcription work it must be bound to inducers_____________.

cAMP -ATP derivative called cAMP

the_________ at the 5' end of the mRNA binds certain proteins that stabilize the transcript and enhance its translation.

capping: a methylated guanine derivative is added to the 5" end of pre-mrna

_________ (CCR) is a regulatory mechanism in which a carbon compound prevents the production of inducible enzymes needed for the metabolism of a different carbon source.

carbon catabolite repression

Catabolism vs Anabolism

catabolism : a set of reactions that degrade compounds, releasing energy(exergonic reaction) . Cells capture that energy and use it to make ATP. -Anabolism or biosynthesis, is the set of chemical reaction that cells use to synthesize and assemble the subunit of macromolecules, using ATP(endergonic reaction).

metabolism can be broken into two categories which are?

catabolism and anabolism

whats is the activator needed for transcription?

catabolite activator protein (CAP) is and activator needed for transcription of the lac operon.

One mechanism of carbon catabolite repression involves an activator called _________ which is required transcription of the _______.

catabolite activator protein ; lac operon

Enzymes involved in essential metabolic pathways, such as glycolysis, are usually ______. Multiple choice question. constitutive inducible repressible

constitutive

Enzymes that are synthesized constantly in a cell are called

constitutive

In the transcriptional regulatory mechanism called repression, the repressor protein can only bind the operator if a molecule called a(n) _________forms a complex with the repressor

corepressor

In the transcriptional regulatory system called repression, the binding of a(n) _______ to the repressor allows this complex to bind to the _______. Thus, RNA polymerase can no longer transcribe the gene. Multiple choice question. aporepressor; promoter corepressor; operator aporepressor; operator corepressor; promoter

corepressor; operator

Optimal expression of genes controlled by an activator requires a(n) ______, which binds to and changes the shape of the activator, facilitating its attachment to the ______.select correct option: facilitator; activator-binding site repressor; DNA-binding site repressor; inducer inducer; activator-binding site

correct: inducer; activator-binding site the following below are incorrect facilitator; activator-binding site Reason: Activation occurs when a molecule called an inducer binds to the activator, changing its shape and facilitating its attachment to the activator-binding site. repressor; DNA-binding site Reason: Activation occurs when a molecule called an inducer binds to the activator, changing its shape and facilitating its attachment to the activator-binding site. repressor; inducer Reason: Activation occurs when a molecule called an inducer binds to the activator, changing its shape and facilitating its attachment to the activator-binding site.

In recent years, a new field of bioinformatics has emerged, which ______. Multiple choice question. aims to replace traditional computer storage methods with information stored in the form of DNA creates the computer technology to store, retrieve, and analyze nucleotide sequence data produces information chips implantable in the human brain couples artificial intelligence with robotics

creates the computer technology to store, retrieve, and analyze nucleotide sequence data

translation occurs in the _________ of eukaryotic protozoa and the _______of bacterial cells.

cytoplasm; cytoplasm

Transcription occurs in the ______of bacteria and the of_______ yeast cells.

cytoplasm; nucleus

Quorum sensing detects cell _______. Multiple choice question. density size volume composition shape

density

difference between exergonic reactions and endergonic reactions?

exergonic reactions: energy is released to break a bond. endergonic reactions: energy is required to make a bond.

Portions of eukaryotic genes that will be transcribed and then translated into proteins; interrupted by introns.

exons

The mRNA in eukaryotes contains both coding and noncoding sequences. The sequences that are ultimately expressed into a protein are called________.

exons

Bacteria use two-component regulatory systems to detect and react to changes in the ______. Multiple choice question. internal environment external environment

external environment

he lac operon is maximally expressed when ______. Multiple choice question. glucose is high and lactose is absent glucose is high and lactose is present glucose is low, regardless of the presence or absence of lactose glucose is low and lactose is present glucose is low and lactose is absent

glucose is low and lactose is present

Carbon catabolite repression is a regulatory mechanism that ensures that a cell ______. Multiple choice question. can mutate so that is can use any carbon source for growth imports and uses lactose if it is present in the medium imports and uses the sugar that allows fastest cell growth only imports and uses glucose from a medium

imports and uses the sugar that allows fastest cell growth

A molecule that can bind to a repressor protein, thereby changing the shape of the repressor and preventing it from binding to an operator, is called an ______. Multiple choice question. inducer sigma fact operon repressor

inducer

why does the repressor block transcription but not inducer?

inducer attaches to the repressor, the repressor, the shape of the repressor changes so that it can no longer attach to the operator. with the repressor unable to bind to DNA, RNA polymerase may transcribe the gene.

In the transcriptional regulatory system known as induction, the binding of a(n) compressor __________, Incorrect Unavailable to the repressor can change its shape so that the repressor can no longer bind to the DNA region known as the ___________ Correct Unavailable. Thus, RNA polymerase can now transcribe the gene.

inducer, operator

Optimal expression of genes controlled by an activator requires a(n) ______, which binds to and changes the shape of the activator, facilitating its attachment to the ______. Multiple choice question. facilitator; activator-binding site inducer; activator-binding site repressor; DNA-binding site repressor; inducer

inducer; activator-binding site

Which of the following types of enzymes are often involved in the transport and breakdown of specific energy sources? Multiple choice question. constitutive inducible repressible

inducible

Repressor proteins block transcription. If the shape of the repressor is changed so that it cannot bind to the operator, ______ occurs and transcription progresses. Multiple choice question. translocation induction repression splicing

induction

Repressor proteins block transcription. If the shape of the repressor is changed so that it cannot bind to the operator, ______ occurs and transcription progresses. Multiple choice question. translocation splicing induction repression

induction

What is the function of RNAi? Multiple choice question. interference with translation by targeting ribosomes interference with translation by targeting all mRNAs interference with translation by targeting a specific mRNA interference with translation by targeting specific tRNA molecules interference with transcription by targeting RNA polymerase

interference with translation by targeting a specific mRNA

segment within a gene that must be removed from pre-mRNA to create a functional mRNA molecule.

intron Segment within a gene that must be removed from pre-mRNA to create a functional mRNA molecule.

Which of the following are removed by the process of splicing carried out in eukaryotic cells? Multiple choice question. exons transposons degenerate codons introns

introns

The _______ uses a repressor that prevents transcription when ________ is not available: the repressor binds the ________.

lac operon ; lactose; operator

lac operon function is?

lac operon trans code proteins that consist of transporting and degradation of lactose. Only turns on when glucose is not available but lactose is.

The lac operon only functions when ______ is present in the medium but ______ is absent from the medium. Multiple choice question. lactose; glucose glucose; allolactose glucose; lactose lactose; maltose

lactose and glucose

Consider the lac operon: When ______ is not available, a repressor prevents transcription. When lactose is available, some of it is converted into ______, which is an inducer.

lactose; allolactose

Capping of mRNA involves the addition of a ______. Multiple choice question. methylated adenine derivative at the 5' end methylated guanine derivative at the 5' end methylated guanine derivative at the 3' end methylated adenine derivative at the 3' end

methylated guanine derivative at the 5' end

ORF stand for?

open reading frame

To which DNA sequence or molecule does a repressor bind? Multiple choice question. operator RNA polymerase promoter silencer enhancer

operator

A cluster of genes that share the same promoter and are transcribed as a single large mRNA molecule is referred to as a(n)

operon

A(n) _______ is a set of regulated genes transcribed as a single mRNA molecule, along with the sequences that control its expression. Multiple choice question. operon transposon transcriptome replicon amplicon

operon

The ability of Escherichia coli to randomly turn on or off the the production of attachment pili is an example of ______. Multiple choice question. two-component regulatory system quorum sensing antigenic variation phase variation

phase variation

Eukaryotic mRNA is first synthesized as an immature transcript called _________-___________. It has to be processed significantly before it forms mature mRNA.

pre-mRNA

All of the following are examples of means by which microorganisms can respond to changing environmental conditions EXCEPT ______. Multiple choice question. signal transduction quorum sensing production of different ribosomes two-component regulatory system

production of different ribosomes

Some prokaryotes are able to detect the density of cells within their population. This phenomenon is called_________.

quorum sensing

This figure shows a process by which bacteria can "talk" to each other after they have reached a critical concentration. The process is known as__________ ____________

quorum sensing

While standard sigma factors recognize promoters for genes that need to be expressed during routine growth conditions, alternative sigma factors ______. Multiple choice question. act by binding to the operator site and either blocking or promoting transcription recognize different sets of promoters, thereby controlling expression of specific groups of genes serve as backup regulators to control expression of these genes for routine growth in the absence of standard sigma factors serve in the process of translating the mRNA into proteins

recognize different sets of promoters, thereby controlling expression of specific groups of genes

what is the name of transcription regulatory system?

repression

DNA-binding proteins control transcription. A binding protein that blocks transcription is called __________a(n) , while one that facilitates transcription is called a(n) __________.

repressor activator

DNA-binding proteins control transcription. A binding protein that blocks transcription is called a(n) ___________, while one that facilitates transcription is called a(n)________.

repressor and activator

prescursor metabolites

serve as carbon skeletons from which subunits of macromolecules can be made. example of this is pyruvate can be converted into any 3 amino acids: alanine, leucine, or valine.

The transmission of information from outside a cell to the inside is known as ______. Multiple choice question. quorum sensing antigenic variation two-component regulatory systems signal transductio

signal transduction

Messenger RNA in eukaryotic cells undergo an important modification called __________, which removes noncoding sequences while joining together the sequences that encode a functional protein.

splicing

Computers help locate protein-encoding regions in DNA by searching for open reading frames, stretches of nucleotide sequences generally longer than 300 bp . that begin with a ______ codon and end with a _________codon

start; stop