Microbial Genetics

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In ___________ transduction , random fragments of host DNA are taken up by the bacteriophage during assembly.

generalized

Genes are made of DNA building blocks called

nucleic acids

Building blocks of DNA, called __________, contain the same sugar and phosphate, but different nitrogenous bases.

nucleotides

True or False: Several codons code for the same amino acid, which is called the redundancy of the code?

true

True or false: A phage is a bacterial virus.

true

True or false: The anticodon for the codon AUG is UAC.

true

Which two of the following operons in E. coli would be repressible?

- An operon encoding amino acids biosynthetic enzymes - An operon encoding vitamin biosynthetic enzymes

An insertion sequence consists of only two genetic elements:

- DNA encoding enzymes for transposition - tandem repeats

Which two statements are correct regarding DNA replication elongation?

- DNA ligase joins the lagging strand fragments. - DNA polymerase I removes the RNA primers used to initiation synthesis.

The lactose repressor protein is allosteric, meaning that it has two binding sites, one for ________ and another for ____________.

- Lactose - the operator DNA sequence

How does RNA differ from DNA in bacteria and eukaryotes?

- RNA is singe-stranded - in RNA, uracil replaces thymine

Events in protein synthesis occur post-translationally

- Removal of the formyl methionine - Protein folding - Addition of cofactor

Which two of the following statements regarding tRNA charging with amino acids are correct?

- The anticodon in tRNA specifies which amino acids it carries. - "Charging" refers to the process of adding an amino acid to a tRNA

Transposable elements are capable of moving from ___________.

- The chromosme to a plasmid - One site in the chromosome to another site in the chromosome - A plasmid to the chromosome

Which two of the following statements regarding DNA packaging are correct?

- The intricate coiling of DNA is required to package it inside the cell. - DNA is thousands of times longer than the cell.

Which two statements regarding eukaryotic transcription are correct?

- Transcription occurs before splicing. - The exon-intron junction is recognized by a spliceosome.

Methods of gene transfer in bacteria

- Transduction - Transformation - Conjugation

Which two of the following statements regarding tRNA structure are correct?

- tRNA has regions that are double-stranded RNA. - The overall structure is termed a cloverleaf.

Which of the following operons in E. coli would be be repressible?

- the pyr operon, encoding pyrimidine biosynthetic enzymes - the rib operon, encoding riboflavin biosynthetic enzymes - the thr operon, encoding threonine biosynthetic enzymes

Which two of the following are responsible for induced mutations?

- ultraviolet light - 2-amino purine

A mutation that affects only a single base pair in DNA is termed a ___________ mutation.

Point

During DNA replication , why are primer sequences necessary?

Primers provide DNA polymerase with the 3' end needed for synthesis

In the central dogma, DNA encodes ___________ which encodes protein.

RNA

_____________ and proteins compose ribosome subunits.

RNA

_______________ _______________ is the enzyme that transcribes DNA into RNA

RNA Polymerase

Which is the main event of transcription initiation?

RNA polymerase binds to the DNA promoter

Which is the main event of transcription elongation?

RNA polymerase joins nucleotides

Which is the main event of transcription termination?

RNA polymerase reaches a terminator region

Which of the following statements regarding the lactose repressor is true?

The lactose repressor is always present in the cell.

___________ refers to the transfer of genes from donor to recipient microorganisms, where the recipient strain shows a change in genetic makeup at the end.

recombination

The ______________ of the lac operon is a gene that encodes a repressor protein.

regulator

During semiconservative _________ the DNA is duplicated prior to binary fission.

replication

The regulator of the lac operon is a gene that encodes

a repressor protein

A nitrogenous-containing molecule found in DNA and RNA that provides the basis for the genetic code is a nitrogenous ______________.

base

Binding of arginine to the arginine repressor protein causes the repressor to

bind to the operator sequence

During conjugation, the donor cell generally retains a copy of the genetic material being transferred. This is termed a ___________ process.

conservative

Biosynthesis of DNA, RNA, and protein ____________ energy.

consumes

A recombinant is defined as an organism that

contains and expresses genes that originated in another organism

The histidine operon is normally expressed to synthesize histidine for the cell. The operon is turned off only when histidine is present in excess, and the excess histidine serves as a ___________ to turn off the operon.

corepressor

The pyramidine nitrogenous bases found in RNA are uracil and __________.

cytosine

Which type of mutation is generally most harmful to cells?

frameshift mutation

The two versions of transduction are

generalized transduction and specialized transduction

Control of enzymes at the level of gene expression ensures that

genes are active only when their enzyme products are required

Some enzymes are tightly so that they are synthesized only under certain conditions. This regulation occurs at the ____________ level.

genetic

The science of heredity is ______________.

genetics

The complete set of chromosomes and genes in an organism is referred to as the ____________.

genome

The __________ is the genetic makeup of an organism that is ultimately responsible for an organism's expressed characteristics.

genotype

The purine nitrogenous bases found in RNA are adenine and __________.

guanine

Viral mRNA is tanslated into viral protein on ____________ ribosomes using __________ tRNA.

host; host

The enzyme beta-galactosidase, encoded in the lac operon, has an enzymatic activity to

hydrolyze lactose

Because lactose is ultimately responsible for stimulating protein synthesis from the lac operon, it is called the ____________________.

inducer

The binding of lactose to the lactose repressor protein causes the repressor to leave the operator region. This happens because lactose

induces a conformational change in the protein

Many catabolic operons are _________, while those that encode anabolic enzymes are _____________.

inducible: repressible

A ___________ can transcribe DNA into RNA and then back into DNA for insertion in a new genomic location.

retrotransposon

The pentose sugar in RNA is ______________, while in DNA the pentose sugar is ______________.

ribose; deoxyribose

The ______________ is a particle composed of two subunits of rRNA that is the site of protein synthesis.

ribosome

Which is an agent that induces changes in DNA?

mutagen

A mutation that produced neither adverse nor helpful changes is termed a ___________ mutation.

neutral

A ___________ mutation results in early termination of the protein

nonsense

In a protozoa or fungal cell, chromosomes are located in the ______________.

nucleus

The DNA genome of DNA animal viruses is replicated in the __________; the genome of RNA viruses is replicated in the _____________.

nucleus; cytoplasm

In replication of DNA, the lagging strand is replicated in a discontinuous manner forming ____________ fragments.

okazaki

The lactose repressor protein binds to the ____________ of the lac operon.

operator

In bacteria, a regulatory gene, a control region, and structural genes collectively are referred to as a(n) _______________.

operon

_____________ ______________ are areas of the genome containing multiple genes which contribute to a new trait for the organism that increases its ability to cause disease.

pathogenicity islands

The process of bacteria turning on or off a group of genes that changes its phenotype in a heritable manner is called ______________ ________________.

phase variation

The characteristics resulting from the interaction of the particular genetic makeup of an organism and the environment is the _______________ of that organism.

phenotype

Phase variation is a type of __________ variation.

phenotypic

within a nucleotide, the ____ group is linked to the 5' carbon of the pentose sugar

phosphate

Donor and the recipient bacterial cells are connected by the sex ____________ during conjugation.

pilus

the protein bridge in conjugation is called the

pilus

A ___________________ is small circular segment of DNA found in the cytoplasm of bacteria that is capable of independent replication and usually contains nonessential genes.

plasmid

In bacterial conjugation, a donor cell with a F (fertility) __________ located in the cytoplasm is considered F+.

plasmid

DNA transfer between bacterial cells typically involves DNA in the form of __________ and ___________.

plasmids and chromosomal fragments

DNA ____________ is the enzyme that synthesizes DNA strands in the 5' to 3' direction.

polymerase

DNA _____________ are enzymes responsible for the replication of DNA.

polymerases

During replication initiation, the enzyme _____________ synthesizes primer sequences.

primase

RNA polymerase binds to which region of DNA to begin transcription?

promoter

The _____________ of the lac operon is a region of DNA that is recognized by RNA polymerase.

promoter

During protein synthesis, many copies of a specific ________________ can be synthesized from a single mRNA transcript.

protein

Which process in bacteria do the antibiotics tetracycline, chloramphenicol, and eryhtromycin specifically inhibit?

protein synthesis

Which type of RNA composes ribosomal subunits together with protein?

rRNA

The process of DNA replication pictured above here can be described as being _____________, due to the production of two daughter DNA strands from two template strands.

semiconservative

A mutation that changes a base but does not change the amino acids sequence of the encoded protein is termed a ____________ mutation.

silent

The following sequence is found at the beginning of a gene in the wild type: 5'-ATGCCAGGTCGTACA-3'. In a related strain of bacteria, the sequence is 5'-ATGCCCGGTCGTACA-3'. Since the codons CCA and CCC both encode proline, this mutation is best describes as a ___________ mutation.

silent

The mRNA sequence AUG, specifying the first amino acid in protein sequences, is called _____________ codon.

start

An organism that has a mutation is called a mutant ________________.

strain

The ______________ of the lac operon is comprised of three genes, each encoding a different enzyme needed to catabolize lactose.

structural locus

______________ RNA is transcribed and then plays a role in translation by carrying amino acids to the ribosome.

t (transfer)

The 3' end of a eukaryotic chromosome that cannot be copied is called the _____________.

telomere

The ________ DNA contains the order of nucleotides that are transcribed into RNA.

template

During which process is mRNA converted into a protein?

translation

:Jumping genes" or _______________, are insertion sequences that can lead to changes in genotype within a cell or between cells.

transposons

An induced mutation arises in DNA from

treatment with ultraviolet light

The term ______________ is a sequence of 3 consecutive nucleotide bases in DNA that encodes an amino acid.

triplet

True or false: The parent strands in a DNA molecule are used a template to synthesize a complementary strand of DNA.

true

The nitrogenous base thymine is only found in DNA, while __________ is only found in RNA.

uracil

The pyrimidine nitrogenous bases found in RNA are cytosine and _________________.

uracil

Which two of the following statements are correct?

-Eukaryotic DNA is linear whereas bacterial DNA is circular -Topoisomerases relieve the superhelical tension as DNA is replicated.

Which two of the following statements regarding plasmids are true?

-Many bacteria carry plasmids in addition to their chromosome. -Plasmids may contain genes that specify resistance to antibiotics.

Select the enzymes that function in DNA replication.

-helicase -ligase -DNA polymerase

How many replication forks are formed from opening a section of a circular DNA molecule during replication?

2

If a DNA molecule contains 15% adenine nucleotides, what percent of cytosine does it contain?

35%

Match the number of genes with the typical organism that carries them in its genome.

A few dozen - virus A few thousand genes - bacterium Tens of thousand of genes - human

Which is the main event of translation termination?

A nonsense codon is reached and the peptide is released from the ribosome.

Which of the following nitrogenous bases is found in both DNA and RNA

Adenine

Purines

Adenine and Guanine

The ___________ test is a method of detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria.

Ames

What is the function of tRNA?

Brings amino acids to the ribosome

Which enzyme adds nucleotide triphosphates to a growing DNA strand?

DNA polymerase

Which is true regarding DNA replication?

Each new DNA helix contains one parent strand and one newly synthesized strand

In bacterial conjugation, a recipient cell having no _____________ plasmid is considered F-.

F

In bacterial conjugation, which term refers to a recipient cell that does not have a fertility plasmid?

F-

True or False: A RNA template is a strand of RNA made from DNA.

False

True or False: DNA polymerase converts DNA into various types of RNA during transcription.

False

True or False: Operons are found in fungi and helminths.

False

Which DNA sequences are found within a gene but do not encode the protein specified by that gene?

Introns

Mutagenic agents and its effect on DNA

Ionizing radiation- forms free radicals that cause breaks in DNA Ultraviolet radiation- crosslink adjacent pyramidines Nitrogen base analogs- compete with natural bases for sites on DNA

Which enzyme completes the final sealing of nicks in a newly synthesized DNA strand?

Ligase

Which is true regarding bacterial chromosomes?

Located in the nucleoid region of the cytoplasm

What amino acid sequence is encoded by the DNA template sequence 3'-TACCGCGCTCTACCG-5'?

Methionine-Alanine-Arginine-Aspartic Acid- Glycine

Which is the largest in terms of molecular size?

Nucleic acid

Which best describes the antiparallel orientation of strands in DNA?

One strand is 5' to 3' and the other is 3' to 5'.

Which antibiotic does not target transcription or translation on bacteria?

Penicillin

Which process repairs DNA that has been damged by ultraviolet radiation using visible light?

Photoactivation

Which of the following is the genetic pattern of viral genomes?

Single or double stranded DNA or RNA

_________ genes are DNA segments that code for proteins.

Structural

What did Griffith's experiment using Streptococcus pneumoniae demonstrate?

That DNA released from a dead cell can be transferred to live cell

The antibiotic rifamycin can be used to treat tuberculosis because

The drug is more active against bacterial RNA polymerase than the human enzyme.

Which is a nitrogenous base found in DNA?

Thymine

Which recombination method involves transfer of DNA via bacteriophages?

Transduction

Horizontal gene transfer

Transfer of DNA from a source other than the parent organisms.

Vertical gene transfer

Transfer of DNA from parent organisms during reproduction.

The process of shifting the ribosome down the mRNA to read new codons is termed ___________.

Translocation

True or false: A mutation is an alteration in the DNA sequence or content of a cell that is passed on when the cell divides.

True

The three stop codons

UAG, UAA, UGA

The structure of DNA was discovered in 1953 by ______________.

Watson and Crick

The biosynthesis of the amino acid histidine requires several enzymes whose genes are organized in the his operon. The his operon would be expected to be active when the cell is growing in a medium contaning.

a low concentration of amino acids

The arginine operon is "on" when the cell is

actively growing

The purine nitrogenous bases found in DNA are guanine and _____________.

adenine

Nucleotide is to nucleic acid as ____________ ______________ is to protein.

amino acid

During translation elongation, peptide bonds form between:

amino acids

tRNA carries ____________ ___________ to the ribosome to build peptide chains during protein synthesis.

amino acids

Which is the main event of translation elongation?

amino acids are joined by peptide bonds

Phase variation occurs when Streptococcus pneumoniae produce a

capsule

A(n) ______________ is the specific sequence of 3 mRNA nucleotides, based on DNA triplet, that encodes a particular amino acid.

codon

each mRNA ______ codes for a particular amino acid which is then bonded with other amino acids during translation to form a protein

codon

A bacterial cell described as ___________ can accept soluble DNA from the surrounding environment.

competent

During which method of gene transfer are bacterial cells in direct contact?

conjugation

_______________ in bacteria refers to horizontal gene exchange via pili

conjugation

Ensuring that the DNA code will be maintained during cell growth and cell ____________ is one of the two essential effects of the structure of DNA.

division

Most DNA damage is resolved by

enzymes

A spontaneous mutation arise in DNA from

errors in DNA replication

In eukaryotes, which DNA sequences encode functional protein?

exons

True or False: A cell with an integrated F factor transmits its genes at lower frequency than does a cell with a free plasmid in the cytoplasm.

false

True or False: A point mutation results from an insertion or deletion of nucleotides, and always leads to a shift of the triplet sequence from the point of mutation downstream.

false

True or False: Deoxyribose is the pentose sugar in RNA

false

True or False: Eukaryotic chromosomes are composed of DNA and RNA.

false

True or False: Mutations are always harmful to cells?

false

True or False: Ultraviolet rays are chemical mutagens.

false

True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.

false

The Y-shaped opening the yellow arrow is pointing to is called the replication _____________.

fork

The lac operon in E. coli regulates the metabolism of ____________.

lactose

Which molecule is the inducer of the lac operon?

lactose

Which strand is replicated discontinuously in segments during DNA replication?

lagging

The newly forming DNA strand that is replicated continuously without segments is called the ___________ strand.

leading

Which type of RNA is a copy of the DNA template corresponding to a protein-encoding gene?

mRNA

Which is the main event of translation initiation?

mRNA binds to the ribosome

template strand

mRNA binds to this strand in transcription

______________ RNA contains the codons for the polypeptide.

messenger

A mutation that leads to the insertion of a different amino acid in the encoded protein is termed a __________ mutation.

missense

Coding strand

the sequence of this strand is the same as the mRNA

In general, a strand of RNA made from DNA is called an RNA

transcript

RNA polymerase binds the DNA promoter to initiate ____________,

transcription

___________ is the process of decoding DNA into messenger RNA.

transcription

One reason protein synthesis is more efficient in bacteria than in eukaryotes because bacterial ____________ and ________________ are simultaneous.

transcription and translation

_______________ involves the transfer of DNA via bacteriophages.

transduction

The process of introducing foreign genes to a plant cell by adding the DNA directly to the cell medium is termed ________________.

transfection

Griffiths's experiment using Streptococcus pneumoniae demonstrated the process of ____________.

transformation

___________ involves the uptake of free DNA by competent bacterial cells.

transformation

The native or __________ type strain exhibits nonmutated characteristics.

wild type


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