Biology 203 - Chapter 9
Which two of the following statements regarding eukaryotic transcription and RNA processing are correct?
-A series of adenosines is added to the mRNA. -Splicing to remove introns occurs in the nucleus.
Place the steps in the correct order to review the steps of mRNA processing in eukaryotes.
-DNA template -Primary transcript -Transcript processing -Exons are spliced -mRNA ready for translation
Horizontal gene transfer - Vertical gene transfer -
-Transfer of DNA from a source other than the parent organisms -Transfer of DNA from parent organisms during reproduction
Select all of the features that you would include if you drew a short segment of DNA.
-double-stranded -helical shape -chains of nucleotides -the backbone of the chains are created by bonds between sugars and phosphates of nucleotides-nucleotides are base -paired with T bonded to A and C bonded to G through hydrogen bonds
Order the following choices to reflect the correct steps of the process of DNA replication.
1) Helicase starts at the origin of replication separating the two strands of DNA, forming two replication forks 2) Primase synthesizes RNA primers 3) Two molecules of DNA polymerase III (one at each replication fork) build DNA by adding nucleotides onto the primers, extending them 4) The leading strand is synthesized continuously while the lagging strand is synthesized in fragments (Okazaki fragments) 5) DNA polymerase I removes the RNA primers and replaces them with DNA 6) DNA ligase joins the Okazaki fragments
Which is the main event of translation termination?
A nonsense codon is reached and the peptide is released from the ribosome
A screening system called the _______ test is used for detecting chemicals with carcinogenic potential.
Ames
The ______ test is a method of detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria.
Ames
Which test is a method of detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria?
Ames
During translation elongation, peptide bonds form between:
Amino acids
Using the figure as a reference, place the steps in the correct order to assess your knowledge of the steps of transcription.
DNA is unwound at the promoter by RNA polymerase. Only one strand of DNA, called the template strand, is copied by the RNA polymerase. This strand runs in the 3' to 5' direction. DNA is unwound at the promoter by RNA polymerase. Only one strand of DNA, called the template strand, is copied by the RNA polymerase. This strand runs in the 3' to 5' direction. As the RNA polymerase moves along the strand, it adds complementary nucleotides as dictated by the DNA template, forming the singlestranded mRNA that reads in the 5' to 3' direction. As the RNA polymerase moves along the strand, it adds complementary nucleotides as dictated by the DNA template, forming the singlestranded mRNA that reads in the 5' to 3' direction. The polymerase continues transcribing until it reaches a termination site and the mRNA transcript is released for translation. Note that the section of the DNA that has been transcribed is rewound into its original configuration. The polymerase continues transcribing until it reaches a termination site and the mRNA transcript is released for translation. Note that the section of the DNA that has been transcribed is rewound into its original configuration.
Okazaki fragments are attached to the growing end of the lagging strand by _______.
DNA ligase
True or false: The chromosome is a small circular segment of DNA found in the cytoplasm of prokaryotes that is capable of independent replication and usually contains nonessential genes.
False
True or false: Viral genomes are always composed of either single or double stranded DNA.
False
Which term represents all of the genetic information within a cell?
Genome
Which is a purine?
Guanine
In bacterial conjugation, which type of donor has the fertility factor integrated into the chromosome?
Hfr
Select the statements that are true of inducible operons to test your understanding of the differences between inducible and repressible operons.
Inducible operons often contain genes for enzymes that function in catabolic processes; Inductible operons will be "turned on" in the presence of the substrate and turned off in its absence; The lac operon is an example of an inducible operon.
Match each mutation with its appropriate description.
Nonsense mutation - A mutation which changes a codon that specifies an amino acid to a stop codon, resulting in premature termination of polypeptide synthesis Missense mutation - A mutation which results in a change in a codon such that a different amino acid is specified Silent mutation - A mutation that changes one codon to a different codon that specifies the same amino acid, such that there is no change in the resulting polypeptide Frameshift mutation - A mutation resulting from an insertion or deletion of bases that causes a change in the reading frame of the mRNA
What are areas of the genome where multiple genes exist that are coordinated to give a new trait and make the bacterium more pathogenic?
Pathogenicity islands
If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE THE BAG RAT?
Point
In the central dogma, DNA encodes ______ which encodes protein.
RNA
Which of the following additions have been made to principles of the central dogma of biology?
RNA can be used to regulate gene function
Select all that apply How does RNA differ from DNA in bacteria and eukaryotes?
RNA is single-stranded In RNA, uracil replaces thymine
Which enzyme transcribes DNA into RNA?
RNA polymerase
Which term refers to the transfer of genes from donor to recipient microorganisms?
Recombination
Select the statements that are true of repressible operons to test your understanding of the differences between inducible and repressible operons.
Repressible operons are usually the "turned on" state and are "turned off" when their product is in adequate supply. The product of the enzymes in the operon functions as a corepressor. Enzymes necessary for the synthesis of amino acids are often encoded by genes in repressible operons.
During ______ DNA replication, the newly made double helices are composed of one parent template and one newly synthesized strand.
Semiconservative
Which of the following is the genetic pattern of viral genomes?
Single or double stranded DNA or RNA
How do an Hfr cell and an F+ cell differ?
The plasmid is integrated into the chromosome of an Hfr cell but not in an F+ cell.
A mutation has occurred during DNA replication while the cell was preparing to divide. As a result of this, the codon ACU of mRNA has now become ACC. Interestingly, there is no change to the protein being made. Why not?
This is a silent mutation.
Which of the following are methods of gene transfer in bacteria?
Transduction Transformation Conjugation
Conjugation, _______, and transduction are methods of gene transfer in bacteria.
Transformation
In Griffith's experiments with Streptococcus pneumoniae, rough nonencapsulated streptococci were converted into smooth encapsulated streptococci in the presence of the heat-killed smooth encapsulated streptococci. Which microbial process had Griffith identified?
Transformation
Which gene transfer method involves the uptake of free DNA by competent bacterial cells?
Transformation
Select the mechanisms below which enable the horizontal transfer of antibiotic resistance genes.
Transformation, Transduction, Conjugation
Which of the following processes does not directly involve DNA?
Translation
Repressible operons are normally turned on in the cell.
True
Transcription occurs within the nucleus or at the nucleoid.
True
True or false: A bacterial cell described as competent can accept soluble DNA from the surrounding environment.
True
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
Unlike DNA, RNA contains the nitrogenous base
Uracil
Most bacterial plasmids carry an origin of replication and at most _____ genes.
a few dozen
The arginine operon is "on" when the cell is
actively growing
Replication of DNA begins at a/an _______ rich area.
adenine-thymine
Split genes _______.
are acted upon by spliceosomes to excise introns and then join exons
Which of the following is not true of an organism's genotype?
are the expressed traits governed by the genes
Cotranscriptional translation occurs in ______.
bacteria
A ______ is a bacterial virus.
bacteriophage
A nitrogen-containing molecule found in DNA and RNA that provides the basis for the genetic code is a nitrogenous
base
Erythromcycin, a macrolide, inhibits protein synthesis _______.
by binding to the ribosome, preventing translocation due to interference with the attachment of mRNA.
The genes of the lac operon in E. coli encode enzymes that
catabolize lactose
The specific sequence of 3 bases in mRNA that encodes a particular amino acid is the ______ whereas the complementary sequence of 3 bases in tRNA that bind to the mRNA is known as the _______.
codon; anticodon
______ in bacteria refers to horizontal gene exchange via pili.
conjugation
During conjugation, the donor cell generally retains a copy of the genetic material being transferred. This is termed a _____ process.
conservative
The following pertain to ribosomes during protein synthesis except _______.
contain codons within their rRNA molecule
In DNA, the base that pairs with guanine is
cytosine
The pyrimidine nitrogenous bases found in DNA are thymine and
cytosine
DNA repair enzymes have as their substrate
damaged DNA
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 arises in DNA from
errors in DNA replication
The process in which mutations are removed and the correct bases added is called ________.
excision repair
DNA replication proceeds in one direction around the bacterial chromosome.
false
Lactose is a corepressor in the lac operon.
false
True or false: Mutations are always harmful to cells.
false
In _____ transduction, random fragments of host DNA are taken up by the bacteriophage during assembly.
generalized
The science of heredity is ______.
genetics
______ 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
All of the following pertain to nitrogenous bases except _______.
guanine pairs with uracil
DNA polymerase adds new nucleotides _______.
in the direction toward the replication fork on the leading strand.
Hfr transfer involves all of the following except _______.
independent plasmid transfer
Select the enzymes that function in DNA replication.
ligase DNA polymerase helicase
A permanent change in the DNA base sequence is a ______,
mutation
A permanent inheritable alteration in the DNA sequence of a cell is a(n)
mutation
A small number of ______ are considered beneficial in that they provide the cell with a useful change in structure or physiology.
mutations
A mutation that changes a normal codon to a stop codon is called a ______ mutation.
nonsense
The ______ DNA strand is the strand that is not directly used for transcription into mRNA during protein synthesis.
nontemplate
Building blocks of DNA, called ______, contain the same sugar and phosphate, but different nitrogenous bases.
nucleotides
The fact that eukaryotic cells have a _______ and bacteria and archaea do not makes their processes of protein translation distinct.
nucleus
All of the following pertain to transcription except _______.
occurs on a ribosome in the cytoplasm.
The lac operon is usually in the ______ position and is activated by a/an _______ molecule.
off; inducer
When a cell is actively growing, the arg operon is _____, and arginine is _____.
on; actively synthesized
Each nucleotide is composed of _______.
one phosphate, one nitrogenous base, and one sugar.
A/An _____ is a group of bacterial genes in a linear arrangement that will be transcribed together.
operon
A ______ is a small circular segment of DNA found in the cytoplasm of bacteria that is capable of independent replication and usually contains nonessential genes.
plasmid
A mutation that affects only a single base pair in DNA is termed a _____ mutation.
point
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
Which enzyme synthesizes primer sequences during replication initiation?
primase
The nontranscribed region of DNA to which RNA polymerase binds to initiate transcription is called the ________.
promoter
RNA polymerase binds to the _______.
promoter sequence
DNA replication is described as ______.
semi-conservative
DNA polymerase can catalyze a dehydration synthesis reaction only at the 3' carbon of the daughter strand of DNA. This means that _______.
since the strands are antiparallel, one strand will grow toward the fork as it opens, and the other strand will grow in fragments away from the fork
In _____ transduction, a particular part of the host genome is included in the virus.
specialized
Mutations that occur because of errors in DNA replication are termed
spontaneous
Select the types of RNA that are directly involved in translation.
tRNA mRNA rRNA
Repressible operons require that ______ binds to the repressor protein before it can bind to the operator.
the product
All DNA nucleotides contain ______.
the same sugar and phosphate, but different nitrogenous bases
The process of introducing foreign genes to a plant cell by adding the DNA directly to the cell medium is termed ______.
tranduction
Which recombination method involves transfer of DNA via bacteriophages?
transduction
The process of introducing foreign genes to a yeast cell by adding the DNA directly to the cell medium is termed
transfection
The RNA molecules that carry amino acids to the ribosomes during protein synthesis are called ________.
transfer RNA
______ involves the uptake of free DNA by competent bacterial cells.
transformation
The term ______ is a sequence of 3 consecutive nucleotide bases in DNA that encodes an amino acid.
triplet
Which term, synonymous with codon, describes a trinucleotide sequence coding an amino acid in DNA?
triplet
Recombinant organisms often exhibit new traits, such as antibiotic resistance or novel metabolic capabilities.
true
Helicase ______.
unwinds DNA
Select all statements that describe features of transcription and translation found in eukaryotes but not in bacteria.
-Genes are interrupted by intervening sequences. -A tail of multiple adenine ribonucleotides is added to the mRNA transcript. -The mRNA transcript must pass through pores to get out of the nucleus. -RNA transcript is processed to remove introns and splice together exons.
Which two of the following statements regarding plasmids are true?
-Plasmids may contain genes that specify resistance to antibiotics. -Many bacteria carry plasmids in addition to their chromosome.
Order the following choices to examine the process of transcription.
-RNA polymerase binds at the promoter region just upstream from the gene -RNA polymerase unwinds the DNA at the promoter site and begins to transcribe template strand of DNA -RNA polymerase moves along the template strand of DNA adding complementary RNA nucleotides, extending the mRNA -Transcription continues until a termination site in the DNA is reached -The mRNA transcript is released
Which two statements regarding eukaryotic transcription and RNA processing are correct?
-The exon-intron junction is recognized by a spliceosome. -Transcription occurs before splicing.
The genes of which microorganism(s) are arranged as operons?
Bacteria
Which type of microbes were first found to utilize the lac operon in order to conserve energy by only expressing genes when the gene products were needed?
Bacteria
Which is true regarding adenine and guanine?
Both are purines
Order the following choices to reflect the correct steps of the process of DNA replication.
Certain cells, called F+ cells, contain a plasmid that codes for a sex pilus to connect to a recipient F- cell and donate a copy of the plasmid. When bacteriophage progeny are being assembled, occasionally a fragment of host DNA is packaged in error and transferred to a new cell by the process of transduction. During transformation, DNA that has been released from a dead cell passes through the cell wall of a competent cell.
The pyrimidine nitrogenous bases found in DNA are thymine and _______.
Cytosine
What is the central dogma hypothesis of genetics?
DNA encodes RNA which encodes protein
Which enzyme adds nucleoside triphosphates to a growing DNA strand?
DNA polymerse
Which is the main enzyme in elongation of a DNA strand during replication?
DNA polymerse
Base substitutions, deletions, and insertions describe mutations in terms of their effect on the _______, whereas missense, nonsense, and silent describe mutations in terms of their effect on the _______.
DNA; protein
Which is true regarding DNA replication?
Each new DNA helix contains one parent strand and one newly synthesized strand
Induced mutations are initiated by errors in DNA replication.
False
RNA molecules are circular and double-stranded, as compared to the linear single-stranded structure of DNA molecules.
False
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: Bacterial conjugation is a sexual process.
False
True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.
False
True or false: Operons are found in fungi and helminths.
False
The antibiotic rifamycin, used to treat tuberculosis, binds and inhibits the activity of
RNA polymerse
_____ _____ is the enzyme that transcribes DNA into RNA.
RNA polymerse
Select which of the following represents a proper pairing of a nucleic acid and one of its components.
RNA, uracil
Select the term that best describes any organism that contains and expresses genes that originated in another organism.
Recombinant
Match the antibiotics with their activity to test your understanding of ways in which antibiotics inhibit protein synthesis.
Rifamycin - Antibiotic binds to RNA polymerase blocking the initiation of transcription. Erythromycin - Antibiotic inhibits the attachment of mRNA to the ribosomes and blocks translation. Tetracycline - Antibiotic binds to ribosome and blocks elongation of polypeptides during translation. Actinomycin D - Antibiotic blocks transcription by binding to DNA and blocking mRNA chain elongation. Aminoglycosides - Inhibit peptide initiation and elongation.
The development of virulent, toxin-producing bacterial strains due to the presence of a temperate phage can occur through the process of ________.
Specialized transduction
Conducting additional research as necessary, drag and drop the labels to accurately depict the mechanism of action for antibiotics that interfere with protein synthesis.
Streptomycin - inhibits peptide initiation and elongation inhibits peptide initiation and elongation Tetracycline - binds to ribosome and prevents polypeptide elongation binds to ribosome and prevents polypeptide elongation Erythromycin - interferes with attachment of mRNA to ribosome interferes with attachment of mRNA to ribosome
Consider the following wild-type DNA sequence on the template strand: TACGACACCTTA Four different mutations of this sequence are indicated. Match the mutated sequence with the type of mutation it represents. Use the genetic code to help you.
TACGACACTTTA - Nonsense mutation TACGTCACCTTA - Missense mutation TACGATACCTTA - Silent mutation TACTGACACCTTA - Frameshift mutation
In order for protein synthesis to begin, which of the following statements reflects the correct sequence of events?
The 5' end of the mRNA binds to the small ribosomal subunit, and the large subunit joins, creating the P and A sites where reactions between codons on the mRNA and anticodons on tRNA are stabilized.
Select the accurate statement reflecting the genotype or phenotype of an organism.
The alleles contained within the cells of an organism comprise its genotype.
Select the most accurate statement reflecting the process of transcription.
Transcription relies upon the action of RNA polymerase.
______ involves the transfer of DNA via bacteriophages.
Transduction
True or false: A phage is a bacterial virus.
True
True or false: DNA replication must occur prior to cell division to ensure that each new cell has a complete set of DNA chromosome(s).
True
True or false: The parent strands in a DNA molecule are used as a template to synthesize a complementary strand of DNA.
True
True or false: The structure of DNA is essential for providing variety since the order of nucleotides is responsible for the unique qualities of each organism.
True
True or false: Within a nucleotide, the phosphate group is linked to the 5' carbon of the pentose sugar.
True
A bacterial cell described as ______ can accept soluble DNA from the surrounding environment.
competent
Donor and recipient bacterial cells are connected by the sex pilus during
conjugation
In DNA replication, ______ unwinds the double helix, primase synthesizes the short RNA primer, and DNA ______ adds nucleotides to the new chain.
helicase; polymerase
A nucleosome is a linear chromosome wound around the _______.
histone
______ gene transfer occurs when organisms acquire genes which did not come directly from parent organisms.
horizontal
An unidentified cell was found to contain introns and exons. It also expresses DNA polymerase and RNA polymerase. Although it exhibits a promoter region, it has no operons. You conclude that this cell _______.
is eukaryotic
The lactose repressor _______.
is inactivated by binding lactose
The lac operon in E. coli regulates the metabolism of
lactose
A nitrogen-containing molecule found in DNA and RNA that provides the basis for the genetic code is a(n) ______.
nitrogenous base
______ ______ 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 island
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 expression of genetic traits is referred to as the organism's ______.
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 recipient bacterial cells are connected by the sex ______ during conjugation.
pilus
DNA Polymerase III _______.
proofreads new DNA
______ 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 operon segment composed of the gene that codes for a protein repressor is called the ________.
regulator
During semiconservative ______, the DNA is duplicated prior to binary fission.
replication
New research has shown that various regulatory RNAs can alter gene function. Examples of such regulatory RNAs are ______.
riboswitches
Select the type of antibiotic that is used to treat cases of tuberculosis, due to its ability to more specifically target bacterial RNA polymerase than the eukaryotic form of the enzyme.
rifamycin
The ______ DNA contains the order of nucleotides that are transcribed into RNA.
template
The parent strands in a DNA molecule are used as a ______ to synthesize a complementary strand of DNA.
template
DNA is semiconservative because the ______ strand will become half of the ______ molecule.
template; finished
Conjugation is a conservative process, meaning that
the donor retains 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
