Microbiology Ch. 9 Questions & Definitions

What is function of tRNA?

Brings amino acids to the ribosome

Which is true regarding DNA replication?

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

The ability of Neisseria gonorrhoeae strains to produce attachment ______ is an example of phase variation.

Fimbriae

The replication ______ is the Y-shaped point on a replicating DNA molecule where the DNA polymerase is synthesizing new strands of DNA.

Fork

A(n) ______ mutation results from an insertion or deletion of nucleotides in multiples of 1 or 2, leading to a shift of the triplet sequence from the point of mutation downstream.

Frameshift

Which type of mutation is generally most harmful to cells?

Frameshift

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

Generalized

______ is the study of the inheritance of living things.

Genetics

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

Genome

The purine nitrogenous bases found in DNA are adenine and ______.

Guanine

In bacterial conjugation, which type of donor has the fertility factor integrated into the chromosome?

Hfr

Match the definition of horizontal and vertical gene transfer:

Horizontal gene transfer = any transfer of DNA that results in organisms acquiring new genes that did not come directly from parent organisms Vertical gene transfer = acquiring genes from parent organisms during reproduction

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

Missense

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

Pilus

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

Point

During replication initiation, the enzyme ______ synthesizes primer sequences.

Primase

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

Promoter

Translation

RNA is used to produce proteins = RNA --> Protein

Which enzyme transcribes DNA into RNA?

RNA polymerase

Which is the main event of transcription initiation?

RNA polymerase binds the DNA promoter

Which is the main event of transcription elongation?

RNA polymerase joins nucleotides

During transcription, RNA polymerase synthesizes ______ from a(n) _____ template.

RNA; DNA

Which term refers to the transfer of genes from donor to recipient microorganisms?

Recombination

rRNA composes ______ subunits together with protein.

Ribosome

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

Start

What kind of gene encodes a protien?

Structural

DNA polymerase III

Synthesizes a new daughter strand of DNA using the parental strand as a template - Makes new DNA 5' to 3' - Can only add nucleotides to an existing chain; cannot begin synthesizing a chain of nucleotides - Adding bases to the new DNA chain; proofreading the chain for mistakes

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

- Chromosomal fragments - Plasmids

Bacterial chromosomes

- Condensed and secured by means of histone-like proteins - Single, circular chromosome

Which of the following are methods of gene transfer in bacteria?

- Conjugation - Transformation - Transduction

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

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

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

Eukaryotic chromosomes

- DNA molecule tightly wound around histone proteins - Located in the nucleus - Vary in number from a few to hundreds - Can occur in pairs (diploid) or singles (haploid) - Appear linear

Which two of the following statements are correct?

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

The two versions of transduction are:

- Generalized - Specialized

How does RNA differ from DNA in bacteria and eukaryotes?

- In RNA, uracil replaces thymine - RNA is single-stranded

Which of the two following statements regarding plasmids are true?

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

Which two of the following statements are correct regarding DNA replication elongation?

- Replication proceeds at a rate of 750 bases per second - DNA polymerase I removes the RNA primers used to initiate DNA synthesis

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

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

Which three of the following events in protein synthesis occur post-translationally?

- addition of cofactor - removal of the formyl methionine - protein folding

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

- an operon encoding amino acid biosynthetic enzyme - an operon encoding vitamin biosynthetic enzymes

The genes of which microorganism(s) are arranged as operons?

Bacteria

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

Base

structural genes

genes that code for proteins

Genotype

genetic makeup of an organism - sum of all types of genes

T/F = A mutation is an alteration in the DNA sequence or content of a cell that is passed on when the cell divides.

True

T/F = The parent strands in a DNA molecule are used as a template to synthesize a complementary strand of DNA.

True

T/F = the expression of the genotype creates traits referred to as the phenotype.

True

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

Uracil

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

Virus = a few dozen genes Bacterium = few thousand genes Humans = tens of thousands of genes

Watson-Crick Model

the double-helix structure of the DNA molecule

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

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

Transposable elements are capable of moving from:

- the chromosome to a plasmid - a plasmid to the chromosome - one site in the chromosome to another site in the chromosome

Which two statements regarding eukaryotic transcription are correct?

- the exon-intron junction is recognized by a spliceosome - transcription occurs before splicing

Which of the two 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 linger than the celll

Nitrogenous bases in DNA

Purines and pyrimidines: - adenine - guanine - cytosine - thymine

The ______ of the genetic code results in several codons encoding the same amino acid.

Redundancy

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

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

Retrotransposon

Okazaki fragments

Short segments of DNA synthesized in a 5' to 3' direction which are then sealed together by DNA ligase to form the 3' to 5' strand

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

Silent

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

Single or double stranded DNA or RNA

Mutations that occur because of errors in DNA replications are termed:

Spontaneous

Which nitrogenous base is found in DNA but not found in RNA?

Thymine

Which recombination method involves 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

Which gene transfer method involves the uptake of free DNA by competent bacterial cells?

Transformation

______ is the process of decoding the messenger RNA into a polypeptide.

Translation

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

Translocation

The enzyme lactose permease, encoded in the lac operon, has an enzymatic activity to:

Transport lactose

"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 UV light

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

Triplet

A ______ is a bacterial virus.

bacteriophage

During translation initiation, the ribosome binds to the ______ RNA transcript.

m

______ RNA contains the codons for the polypeptide.

m

______ is a copy of the DNA template corresponding to a protein-encoding gene.

mRNA

Basic unit of DNA

nucleotide: - phosphate - deoxyribose sugar - nitrogenous base Covalent bonds

Which type of RNA comprises ribosomal subunits?

rRNA

Select the enzymes that function in DNA replication:

- ligase - helicase - DNA polymerase

Which two of the following statements regarding eukaryotic transcription are correct?

- splicing to remove introns occurs in the nucleus - a series of adenosines is added to the mRNA

An insertion sequence consists of only two genetic elements:

- tandem repeats - DNA encoding enzymes for transposition

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

-the operator DNA sequence - lactose

Replication fork

A Y-shaped region on a replicating DNA molecule where new strands are growing - The place in the helix where the strands are unwound and replication is taking place - Each circular DNA molecule will have two replication forks - DNA molecule must be unwound and separated by helicase before DNA polymerase III can function - DNA topoisomerase (DNA gyrase) is used to relive tension in the strand and to recompact the molecule when it is fully replicated

binary fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

DNA ligase

A linking enzyme essential for DNA replication - catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain - final binding of nicks in DNA during synthesis & repair

Primer

A short segment of DNA that acts as the starting point for a new strand - a fragment of RNA that is inserted initially by RNA primase during replication before being replaced by DNA

The arginine operon is "on" when the cell is:

Actively growing

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

Adenine

During translation elongation, peptide bonds form between:

Amino acids

tRNA carries ______ ______ to the ribosome to build people peptide chains during protein synthesis.

Amino acids

RNA primase

An enzyme that creates an RNA primer for initiation of DNA replication.

DNA topoisomerase II (DNA gyrase)

An enzyme that unwinds and winds coils of DNA that form during replication and transcription - relives additional coiling ahead of replication fork

The biosynthesis of DNA, RNA, and protein is a(n) ______ process.

Anabolic

In DNA, the two strands of the helix are arranged in ______ orientation.

Anti-parallel

A ______ is a discrete cellular structure composed of a neatly packaged DNA molecule.

Chromosome

Match the strand of DNA with its correct definition:

Coding strand = the sequence of this strand is the same as the mRNA Template strand = mRNA binds to this strand in transcription

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

Codon

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

Competent

What is the function of rRNA?

Composes ribosomal subunits

______ in bacteria refers to horizontal gene exchange via pili.

Conjugation

In the bacterium E. coli, where is the chromosome located?

Cytoplasm

The pyrimidine nitrogenous bases found in RNA are uracil and ______.

Cytosine

What is the central dogma hypothesis of genetics?

DNA encodes RNA which encodes protein

Transcription

DNA is used to synthesize RNA = DNA --> RNA

The structural locus of the lac operon has genes that encode:

Enzymes to catabolize lactose

In eukaryotes, which DNA sequences encode functional protein?

Exons

T/F = UV rays are chemical mutagens.

False

Match the mutagenic agents and its effects on DNA:

Ionizing radiation = forms free radicals that cause breaks in DNA UV radiation = crosslinks adjacent pyrimidines Nitrogen base analogs = compete with natural bases for sites on DNA

The newly forming DNA strand that is discontinuously replicated in segments is called the ______ strand.

Lagging

Which strand is replicated continuously without segments during DNA replication?

Leading

The final sealing of nicks in a newly synthesized DNA strand is catalyzed by the enzyme:

Ligase

semiconservative replication

Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand - new strand grows in 5' to 3' direction

An agent that induces changes in DNA is a(n):

Mutagen

Which term refers to an organism that has a mutation?

Mutant

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

Neutral

The ______ DNA strand is the strand that is not directly used for transcription into mRNA during protein synthesis.

Nontemplate

Genes are made of DNA building blocks called:

Nucleic acids

Which is largest in terms of molecular size?

Nucleic acids

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

Nucleotides

In protozoal or fungal cell, chromosomes are located in the ______.

Nucleus

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

Okazaki

The ______ of the lac operon is a region of DNA that acts as an on/off switch for transcription.

Operator

Which operational unit in bacteria consists of a regulatory gene, a control region, and structural genes?

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

Within a nucleotide, the ______ group is linked to the 5' carbon of the pentose sugar

Phosphate

The 3' end of a eukaryotic chromosome that cannot be copies is called the:

Telemore

The process of transcription ______ results in the release of a completed RNA transcript.

Termination

Conjugation is a conservative process, meaning that:

The donor bacterium retains ("conserves") a copy of the genetic material being transferred.

The antibiotic rifamycin can be used to treat tuberculosis because:

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

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

The lactose repressor is always present in the cell.

Leading strand

The strand of new DNA that is synthesized continuously in a 5' to 3' direction

Lagging strand

The strand of new DNA that must be synthesized in short segments (in a 5' to 3' direction) - Later sealed together to form a strand in the 3' to 5' direction

codons/triplets

Three consecutive bases o the DNA strand - A gene differs from another in its composition of triplets - Each triplet represents a code for a particular amino acid - When the triplet code is transcribed and translated, it dictates the type and order of amino acids in a polypeptide chain

The pyrimidine nitrogenous bases found in DNA are cytosine and ______.

Thymine

Regulatory genes

control gene expression

Phenotype

expression of genotype - creates traits - physical