MIcrobiology Exam 2

The ____ is the nucleotide sequence in the DNA of a cell or organism.

genotype

In ______ gene transfer, DNA moves from one organism to another, while in _________ gene transfer, DNA is passed from parent cell to its progeny.

horizontal , vertical

A prokaryote that Carrie's one gene is called ____ RNA while a transcript that Carrie's multiple genes is called _______RNA

monocistronic , polycistronic

A(n)_______ is a change In nucleotide sequence of DNA that is passed on to daughter cells.

mutation

Which of the following are replicons?

plasmid and chromosome

RNA polymerase binds to a ____ to begin transcription.

promoter

When horizontal gene transfer occurs between a donor and recipient cells , the resulting cells are called ______

recombinants

Enzymes that are usually synthesized but are not made when they are not needed are _____enzymes

repressible

The process of translation requires three major structures. What are they ?

tRNA,mRNA,ribosomes

The following events happen during the elongation phase of translation.

1.binding of second charged tRNA 2.formation of peptide bond 3. translocation of the ribosome 4.binding of third charged tRNA

What does each nucleotide consists of ?

A 5-carbon sugar (deoxyribose ) , a phosphate group , and one of four nucleobases (A,T,G , or C).

Why is regulation of gene expression important?

A cell does not need all of its encoded proteins at the same time

Why is regulation of gene expression important?

A cell does not need all of its encoded proteins at the same time.

In carbon catabolite repression , CAP functions as an ____, while cAMP functions as an

Activator ; inducer

What happens after an F+ donor transfers a strand of an F plasmid to an F- recipient ?

Both become F+

During bacterial conjugation,synthesis of a new strand of F plasmid DNA occurs in____

Both the donor and recipient

Transcription

Carried by an enzyme called RNA polymerase

Fundamental aspect of the regulation ?

Cell's ability to quickly destroy mRNA.within a few minutes of being produced , transcripts are degrades by cellular enzymes.

If both glucose and lactose are present in a medium, why is the lac Operon not transcribed ?

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

monocistronic

Describes an RNA transcript that Carrie's one gene

antiparallel

Describing the opposite orientation of the strands in a DNA double helix with one strand running in the 5' to 3' direction and the other in the 3' to 5' direction.

Mutant cells in bacterial cultures can be isolated by _________ selection and _______selection methods

Direct , indirect

Two methods used to identify mutants in a culture are _____and _______selection

Direct ; indirect

DNA replication

Duplication of a DNA molecule

Which of the following statements are true about events that take place during the elongation phase of translation ?

Empty tRNAS leave the ribosome via the E-site. tRNAS carrying amino acids occupy the A-site and the P-site of the ribosome . A peptide bond is formed between amino acids on adjacent tRNAs.

After transfer of the F plasmid is complete ,both the donor and recipient cells are now considered _____,so they can act as donors of F plasmid

F+

In the most thoroughly studied example of bacterial conjugation , the term ______ designates a donor cell with an F plasmid , whereas those who lack the F plasmid are termed ____

F+,F-

DNA-binding proteins that bind to DNA always inhibit transcription.

False

A____ is a sequence of nucleotides that usually codes for one functional protein

Gene

Which of the following terms describes the sequence of nucleotides ( genetic makeup ) of an organism cell?

Genotype

The lac Operon is maximally expressed when ______

Glucose is low and lactose is present

DNA replication in order

Helicase,Primase, DNA polymerase, DNA ligase

DNA replication

Helicases unwind the double helix at the replication fork , primases synthesizes the short RNA primer , and DNA polymerase adds nucleotides to the new chain

If DNA acquired through horizontal gene transfer is not a replicon, then a process called ______ recombination must occur for that DNA to be passed on to daughter cells

Homologous

During horizontal gene transfer in bacteria , the transformed donor DNA may be integrated into recipients genome via a process called _____

Homologous recombination

Carbon catabolite repression is a regulatory mechanisms that ensures that a cell _____

Imports and used the sugar that allows fastest cell growth

terminator

In transcription, a DNA sequence that stops the process.

What enzyme is often involved in the transport and breakdown of specific energy sources ?

Inducible

The E-site of the ribosome ______

Is responsible for the release of tRNA

The E-site of the ribosome

Is responsible for the release of the tRNA

An organism that has a mutation is called a

Mutant

Which term refers to organism that has a mutation?

Mutant

Genetic change in bacteria occurs through which two mechanisms?

Mutation, horizontal gene transfer

spontaneous mutations are important because ____

They allow populations of bacteria to adapt to a changing environment.

DNA-binding proteins control transcription. A binding protein that blocks transcription is called an ______ while one that facilitates transcription is called _____

Repressor,Activator

The return of gene from a mutated state to its original, non-mutated state is called a ____

Reversion

________ is the change of mutated genetic sequence back to its original, non-mutated form.

Reversion

What initiates translation?

Ribosomes assemble on the mRNA

The native or wild type strain describes the typical phenotype of strains isolated from nature .

True .

The native or _____ _______ strain describes cells that carry non-mutated DNA.

Wild, type

A linear stand of DNA

Will always have a 5'-PO4 at the end and a 3'-OH at the other .( Are often referred to as the 5'end (5 prime end) and the 3'end ( 3 prime end)

In the presence of lactose , the lac repressor is _____ to all o lactose and so _______to the operator

bound; cannot bind

The native or ______ ______ strain describes cells that carry non-mutated DNA.

wild,type

In general, the chromosome of a bacterial cell is a ________ DNA molecule that is replicated_______.

Circular ; bidirectionally from one origin of replication.

Characteristics of DNA?

DNA is usually double-stranded , helical structure . Each strand is a chain of deoxyribonucleotide subunits , more commonly called nucleotides .

complementary

In DNA structure , describes the nucleobases that characteristically hydrogen bond to one another ; A (adenine ) is complementary to T(thymine), and G (guanine) is complementary to C (Cytosine).

___enzymes are usually not synthesized but are made when they are needed by a cell

Inducible

base pairing

The hydrogen binding of adenine (A) to thymine (T) and cytosine (C) to guanine (G).

origin of replication

The initiate replication of a DNA molecule , specific proteins must bind to a specific DNA sequence

Translation

The process by which the information carried by mRNA is used to synthesize the encoded protein(polypeptide).

Transcription

The process by which the information encoded in DNA is copied into RNA,the process of synthesizing RNA from a DNA template.

Donor and recipient bacterial cells are connected by a sex_____ during conjugation.

pilus

In carbon catabolite repression (CCR) regulatory mechanism called inducer exclusion,__

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

Carbon, Catabolite,repression (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.

.......

When lactose ; is not available, a repressor prevents transcription.when lactose is available, some of it is converted into allolactose , which is an inducer.

.......

the process of bacterial transformation involves the uptake of naked DNA by competent bacterial recipient cells.

.......

Place the steps of F plasmid transfer in the correct order. Start with the earliest at the top

1.F pilus makes contact with recipient cell 2.One strand of F plasmid is cut in origin of transfer 3. single strand and of F plasmid is transferred to recipient cell. 4. Complement of the transferred stand is synthesized.

A bacterial cell described as ____can take up DNA from surrounding environment

Competent

Cells that have the ability to take up DNA from the environment are called _____ cells

Competent

Genome

Complete set of genetic information in a cell or virus.

A plasmid that can directs its own from donor to recipient cells is called an ____plasmid

Conjuative

In bacteria , _____ refers to DNA transfer requiring cell to cell contact

Conjugation

Enzymes involved in essential metabolic pathways, such as glycolysis , are usually ___

Constitutive

Enzymes that are synthesized constantly in a cell are called.

Constitutive

What is the genome of all cells composed of ?

DNA , but some viruses have an RNA genome

DNA

DNA is transcribed into RNA, and RNA is translated into protein.

What happens to the repressor of the lac Operon when lactose is not available?

It is functional and can bind to the operator.

The lac Operon only functions when ____ is present in the medium but ____is absent from the medium

Lactose ;glucose

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

Operator;proceeds

A cluster of genes that share the same promoter and are transcribed as a single late mRNA molecule is referred to as a ?

Operon

An ____ is a set of regulated genes transcribed as a single mRNA molecule, along with the sequences that control its expression.

Operon

To start translation. The initiating tRNA occupies the ______ site; in subsequent steps the tRNAs enter through ________site

P;A

The ________ is the observed characteristics of an organism.

Phenotype

Replicon

Piece of DNA that contains an origin of replication and there for can potentially be replicated by a cell

The structure connecting these two cells is F______ and is formed during the mechanism of DNA transfer called _______

Pillus , conjugation

When describing conjugation in Gram-negative bacteria , a donor cell with an F ______is considered F+,while that without this structure are termed F-.

Plasmid

The initiate transcription, RNA polymerase needs the

Promoter

Transcription is initiated when RNA polymerase binds to a ______ region of the DNA.

Promoter

Transcription is carried out by an enzyme called

RNA polymerase

What enzyme binds to a DNA promoter region to initiate transcription ?

RNA polymerase

While standard sigma factors recognize promoters for genes that need to be expressed during routine growth conditions , alternative sigma factors

Recognize different sets of promoters , thereby controlling expression of specific groups of genes.

The function of mRNA is to ____

Serve as a template for protein synthesis

Bacterial cells can control which genes are transcribed by producing different types of _____ factors , each binding to a specific promoter

Sigma

The part of bacterial RNA polymerase that recognizes a promoter is a subunit called ____

Sigma factor

During conjugation , the F plasmid nucleus acid that transfers is _____

Single -stranded DNA

Random genetic changes that result from normal cellular processes are ______

Spontaneous mutations

During what process is the information in mRNA used to make protein ?

TRANSLATION

What is the central dogma of molecular biology?

The flow of information is from DNA to RNA to protein.

Gene

The functional unit of the genome ;it encodes a product, most often a protein

gene expression

Transcribing and then translating the information in DNA to produce the encoded protein's

Alternative sigma factors allow cells to directly control ______

Transcription

Which two essential cellular processes directly involve DNA?

Transcription , DNA replication

Catabolite activator protein (CAP) is needed for which of the following functions?

Transcription of the lac Operon

In prokaryotes , genes can be transferred from a donor to a recipient via three different mechanism :

Transduction, conjugation, transformation, bacterial transformation.

Main 3 methods of gene transfer in bacteria ?

Transduction, transformation , conjugation

Which mechanism of gene transfer involves uptake of "naked" DNA by competent bacterial recipient cells ?

Transformation

The native or wild type strain describes the typical phenotype of strains isolated from nature

True

What is transcribed from a DNA template and translated during proteins synthesis ?

mRNA

polycistronic

mRNA that Carrie's more than one gene.

Which of the following describes an organism's observable characteristics?

phenotype

Mutations that arise naturally during cellular metabolism, and not as a result of exposure to mutation-causing agents , are called _______ mutations

spontaneous

Recombinants

A cell that carries a DNA molecule derived from two different DNA molecules.

Which of the following are characteristics of recombinants?

They result from horizontal gene transfer , they have properties of both donor and recipient cells.

If a scientist is working with bacteria that have typical phenotype of those isolated from nature , the bacteria are considered to be ___ type

WILD

The term used to describe a gene when it is found in its natural ,non-mutated, form is ________type.

Wild

The term used to describe a gene when it is found it is found in its natural , non-mutated, form is ______type.

Wild

In general , the chromosome of a bacterial cell is ______a DNA molecule that is replicated ____

Circular ; bidirectionally from one origin of replication