Microbial Genetics
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
