Microbiology Chapter 8

What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands? DNA has a helical shape. DNA is double-stranded. DNA is antiparallel. DNA is flexible.

What is the function of the connector proteins? They enable one parental DNA strand and one newly synthesized DNA strand to be held together. They allow DNA synthesis to occur in the 3' to 5' direction. They link the leading strand DNA polymerase and the lagging strand DNA polymerase together. They produce the Okazaki fragments.

Which DNA strand is synthesized continuously? Leading strand Lagging strand Neither the leading nor the lagging strand is synthesized continuously. The leading and lagging strands are both synthesized continuously.

Which of the following are terms associated with Okazaki fragments? DNA ligase Lagging strand Discontinuous Lagging strand, DNA ligase, and discontinuous

Why is the DNA synthesis of the lagging strand considered discontinuous? The synthesis is moving in the opposite direction from the replication fork. The lagging strand only requires one primer instead of multiple primers. The lagging strand only produces single-stranded DNA molecules. DNA synthesis on the lagging strand occurs 3' to 5'.

What is the initial target of RNA polymerase? The promoter The terminator region The template DNA

RNA polymerase is guided by the coding strand of DNA. RNA strand. template strand of DNA.

RNA that has hydrogen bonded to itself forms a termination protein. terminator sequence. promoter sequence. stem loop.

How would one increase the concentration of a particular polypeptide in a cell? Increase the level of transcription Increase the concentration of promoters Increase the amount of DNA

During elongation, how is the RNA synthesized? 5' to 3' Right to left Left to right 3' to 5'

During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome? E site P site A site

How does the ribosome know if the entering charged tRNA is correct? The preceding amino acid will not permit it to enter the A site. The anticodon on the tRNA base pairs to the codon on the mRNA. The incorrect tRNA does not fit into the A site.

Where would one find an uncharged tRNA molecule in a ribosome? In the A site In the A and P sites In the P site In the P and E sites In the A, P, and E sites In the E site

What kind of bond is formed when two amino acids join together? A peptide bond A polar bond A hydrogen bond An ionic bond

How is translation terminated? When the A, P, and E sites are all filled When the ribosome runs out of the mRNA When a protein called a release factor enters and binds to the A site When there are no more charged tRNA molecules

What is considered to be the average natural mutation rate that occurs during DNA replication? One in every billion nucleotides replicated. One in every million nucleotides replicated. One in every trillion nucleotides replicated. One in every ten thousand nucleotides replicated.

A mutation that affects the genotype of an organism but not the phenotype is called nonsense mutation. frameshift mutation. silent mutation. missense mutation.

A base insertion or deletion in the translated region of the gene may lead to silent mutation. nonsense mutation. frameshift mutation. missense mutation.

A base substitution that changes a codon coding for an amino acid to stop a codon is called frameshift mutation. missense mutation. silent mutation. nonsense mutation.

How frequently do silent mutations occur? One out of every billion mutations One out of every three mutations Half of all mutations One out of every million mutations

What is unique about transduction compared to normal bacteriophage infection? The bacteriophage does not erupt from an infected cell during transduction. Transduction transfers DNA from the chromosome of one cell to another. The bacteriophage takes fragments of the cell with it during transduction.

How is generalized transduction different from specialized transduction? Specialized transduction uses animal viruses instead of bacteriophage. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage. Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. Only one specific host gene is transferred in both specialized transduction and generalized transduction.

A transducing phage has a viral coat made of host proteins. cannot infect new host cells. is a lysogenic bacteriophage. contains fragments of the host chromosome instead of the viral genome.

When a transducing phage interacts with a new host cell, the DNA from the previous host can recombine with the new host chromosome. the new host cell will be lysed. it will cause the new cell to produce more transducing phage.

When the cell is NOT in the presence of tryptophan, RNA polymerase can transcribe mRNA. the repressor proteins bind to the operator. the repressor proteins are active. structural genes are not transcribed.

When is the repressor protein transcribed? It is always transcribed. Only in the absence of tryptophan Only in the presence of tryptophan

Why is the tryptophan operon turned off in the presence of tryptophan? Tryptophan is not an important amino acid for cells. Tryptophan can be used over and over again in the cell. Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.

What is the overall function of the trp operon? To always make sure the operator is being bound to repressor proteins To ensure that the cell has a supply of tryptophan at all times To control the production of repressor proteins To block RNA polymerase from the structural genes

According to the animation, how do the repressor proteins block the transcription of the structural genes? It binds to the repressor when deactivated. It binds to the promoter when deactivated. It binds to the repressor gene when activated. It binds to the repressor gene when deactivated. It binds to the promoter when activated. It binds to the operator when activated.

What is the function of the conjugation pilus? It carries the chromosome of F- cells. It pulls the F+ and F- cells together. It contains an F plasmid. It converts F- cells into F+ cells.

What is required by an F- cell to become an F+ cell? Conjugation pilus An F- cell to be a recipient F plasmid F+ chromosome

What is the key difference between donor cells and recipient cells? Cell membranes Size An F plasmid A chromosome

What cellular macromolecule is the fertility factor comprised of? Lipid Carbohydrate Nucleic acid Protein

At which point does a recipient cell become an F+ cell? 1. Fusion of the cell membranes 2. Attachment of the sex pilus 3. Transfer of the single stranded F factor 4. Pulling of donor and recipient cells together 5. Formation of the complementary strand of the F factor 5 1 4 3 2

A gene is best defined as any random segment of DNA. a sequence of nucleotides in DNA that codes for a functional product. three nucleotides that code for an amino acid. the RNA product of a transcribed section of DNA. a sequence of nucleotides in RNA that codes for a functional product.

DNA is constructed of two complementary strands of nucleotides bonded AC and GT. two strands of identical nucleotides in a parallel configuration with hydrogen bonds between them. a single strand of nucleotides with internal hydrogen bonding. two strands of nucleotides running in an antiparallel configuration. None of the answers is correct.

Which of the following is NOT a product of transcription? mRNA rRNA tRNA a new strand of DNA None of the answers are correct; all of these are products of transcription.

An enzyme that copies DNA to make a molecule of RNA RNA polymerase. DNA ligase. DNA helicase. transposase. DNA polymerase.

Which of the following is a DNA strand complementary to CGA ATC AGC? GCT TAG TCG TAG GCT GAT CGA ATC AGC GCU UAG UCG