Chapter 8: Microbial Genetics

According to the animation, ribosomes move along the mRNA in which direction? Either 5' to 3' or 3' to 5' 5' to 3' 3' to 5'

5' to 3'

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

A peptide bond

A peptide bond

A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O).

What results from the process of translation? Ribosomes tRNA A polypeptide mRNA

A polypeptide Translation is the process by which a protein is synthesized from the information contained in a molecule of messenger RNA (mRNA).

What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A? The codon would now code for Trp instead of Cys. A stop codon would be introduced prematurely. The amino acid Cys would still be coded.

A stop codon would be introduced prematurely.

Genetic change in bacteria can be brought about by conjugation. transformation. transduction. mutation. All of the answers are correct.

All of the answers are correct.

How is bacterial translation different from eukaryotic translation? -Bacterial translation does not involve ribosomes. -mRNA is read 3' to 5'. -Bacteria can begin translation before transcription has terminated.

Bacteria can begin translation before transcription has terminated.

Messenger RNA (mRNA)

Carry info for making specific proteins from DNA to RNA

Guanine

Cytosine

Which enzyme breaks the hydrogen bonds during replication? ATP DNA helicase Stabilizing proteins Replication fork

DNA helicase

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

DNA is flexible

The molecule that seals the gaps between the pieces of DNA in the lagging strand is? DNA ligase. the replication fork. DNA polymerase. RNA. the leading strand.

DNA ligase

Which of the following build(s) new strands of DNA? The origins of replication The leading strand Parental DNA DNA polymerases The lagging strand

DNA polymerases

Cells use ______ to store information, while ________ are used to perform activities to keep the cell alive.

DNA, Proteins

Transfer RNA (tRNA)

Deliver Amino Acids to ribosomes

Some cells may contain multiple genomes. True/False

FALSE

DNA ligase adds nucleotides to the lagging strand. True/ False

FALSE This statement is FALSE. DNA ligase seals the gaps between segments of DNA in the lagging strand. It does not add nucleotides to the lagging strand.

Bacteria typically contain multiple chromosomes. True False

False

Ribosomal RNA (rRNA)

Form Ribosomes

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

GCT TAG TCG DNA forms complementary strands by base pairing A with T and C with G.

Frederick Griffith did experiments on genetic transformation. Which of the following statements about his experiments is accurate? -Griffith used only pathogenic bacteria in his experiments. -Griffith used bacteria in which the non-pathogenic strain was encapsulated but the pathogenic strain was not. -The combination of living non-encapsulated bacteria and heat-killed encapsulated bacteria did not cause disease. -Griffith found that DNA released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent.

Griffith found that DNA released from dead (virulent) bacteria entered live (avirulent) bacteria and changed them genetically, causing them to become virulent. This result indicated that the live bacteria obtained genetic information (DNA) from the dead bacteria. In this case, the new genes provided directions for synthesis of the capsule, which allowed the live bacteria to become virulent.

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

In the P and E sites

Which operons are never transcribed unless activated? Inducible operons Repressible operons Inducible and repressible operons

Inducible operons

An ionic bond

Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions

In which direction does the replication fork move? -It moves ahead of the newly synthesized DNA. -It moves ahead of the unzipped DNA. -It moves towards the stabilizing proteins. -It moves from the double-stranded DNA to the single-stranded DNA.

It moves ahead of the newly synthesized DNA

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

Lagging strand, DNA ligase, and discontinuous

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

Leading strand

As shown in the animation, the start codon also codes for which amino acid? Alanine Glycine Serine Methionine Proline

Methionine = Start Codon

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

P site

According to the animation, which of the following makes mRNA from the information stored in a DNA template? RNA polymerase DNA polymerase Ribosomes tRNA

RNA polymerase

Which statement regarding genes and evolution is true? -Today's plethora of microorganisms is the result of an extremely brief period of genetic recombination events. -If an organism has a mutation, it will be less "fit" (less able to reproduce) than other organisms. -Random, heritable genetic mutations are a source of genetic variation. This variation is necessary for natural selection to occur. -Mutations function to prevent the offspring of an organism from evolving.

Random, heritable genetic mutations are a source of genetic variation. This variation is necessary for natural selection to occur. In some cases, random, heritable genetic mutations can confer differential (greater) reproductive success to an organism in a given environment. This is the foundation of natural selection, which is a key evolutionary mechanism.

Which operons are always transcribed unless deactivated? Inducible operons Repressible operons Inducible and repressible operons

Repressible operons

Which finding is most surprising from Griffith's experiments? -S strains are able to escape phagocytosis. -R strain cells fail to produce a capsule. -S strain cells kill the mice. -S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.

S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.

How many codons code for the amino acid arginine? One Six Three Four

Six

What ensures that the single strands of DNA do not come back together? The replication fork DNA helicase Stabilizing proteins ATP

Stabilizing proteins

Because the two strands of parental DNA run in opposite directions, the new strands must be made in different ways. True/ False

TRUE

The lagging strand is made of a series of pieces that must be joined together to make a continuous strand. True/ False

TRUE

The two strands of parental DNA are separated during DNA replication. True/ False

TRUE

DNA polymerase builds a new strand by adding DNA nucleotides one at a time. True/ False

TRUE - DNA Polymerase needs to read each sequence to make sure it's correct.

What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells? -The S strain was revived by the presence of the host's immune system. -The S strain fused with the R strain, making it resistant. -The R strain picked up the S strain DNA, enabling it to produce a capsule. -The R strain cells picked up the capsules from the S strain cells.

The R strain picked up the S strain DNA, enabling it to produce a capsule

How does the ribosome know if the entering charged tRNA is correct? -The incorrect tRNA does not fit into the A site. -The anticodon on the tRNA base pairs to the codon on the mRNA. -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.

What characteristic of the S strain allows it to evade the immune system of the mice? -The cells have a capsule. -They are naturally competent. -They are genetically engineered to be resistant to killing. -They are resistant to heat.

The cells have a capsule.

A polar bond

The greater the electro negativity difference, the more ionic the bond is. Bonds that are partly ionic are called polar covalent bonds.

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

The lagging strand only requires one primer instead of multiple primers.

Which statement about DNA replication is CORRECT? The lagging strand is built continuously. The leading strand is built continuously, and the lagging strand is built in pieces. The lagging strand is one of the strands of parental DNA. The leading strand is one of the strands of parental DNA. DNA ligase helps assemble the leading strand.

The leading strand is built continuously, and the lagging strand is built in pieces.

According to the animation, where on the DNA strand does a repressor bind? The structural genes The operator The promoter The inducer

The operator

A hydrogen bond

The partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. What is this attraction called?

Which of the following genetic elements is transcribed into a single mRNA? The operator The repressor The inducer The structural genes The promoter

The structural genes

How do stabilizing proteins work on the DNA? -They bind to the double-stranded DNA. -They use ATP to break the hydrogen bonds. -They bind to the single-stranded DNA. -They form the replication fork.

They bind to the single-stranded DNA

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 link the leading strand DNA polymerase and the lagging strand DNA polymerase together. -They produce the Okazaki fragments. -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.

Adenine

Thymine

Which of the following amino acids is coded by only one codon? His Tyr Trp Phe Glu

Trp

Recombination will always alter a cell's genotype. True False

True

How is translation terminated? -When a protein called a release factor enters and binds to the A site -When there are no more charged tRNA molecules -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

Assume the two E.coli strains shown below are allowed to conjugate. Hfr: pro+, arg+, his+, lys+, met+, ampicillin-sensitive F-: pro-, arg-, his-, lys-, met-, ampicillin-resistant What supplements would you add to glucose minimal salts agar to select for a recombinant cell that is lys+, arg+, amp-resistant? -ampicillin, lysine, arginine -ampicillin, proline, histidine, lysine -lysine, arginine -proline, histidine, methionine -ampicillin, proline, histidine, methionine

ampicillin, proline, histidine, methionine

Okazaki fragments

are short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication.

GAU codes for aspartic acid. tryptophan. proline. serine. isoleucine.

aspartic acid.

Competent cells are cells that -are also considered "rough-strain" based on colony phenotype. -can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. -have the ability to produce capsules. are killed by heat.

can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination

Which of the following is a method of vertical gene transmission? transformation conjugation cell division transduction

cell division: Vertical transmission refers to transmission from parent to offspring, which occurs during cell division.

Knowledge Deleting or inserting one nucleotide pair in the middle of a gene is an example of which of the following? nonsense mutation missense mutation frameshift mutation base substitution

frameshift mutation: Deletions or insertions result in a change in the reading frame of a gene (the three-nucleotide groupings for codons). Thus, they are termed frameshift mutations.

Which of the following can be translated into protein? tRNA mRNA, tRNA, and rRNA are all translated into protein. rRNA mRNA

mRNA

Transcription produces which of the following? mRNA rRNA tRNA mRNA and tRNA mRNA and rRNA mRNA, tRNA, and rRNA are all produced by transcription.

mRNA, tRNA, and rRNA are all produced by transcription.

In the figure, the antibiotic chloramphenicol binds the 50S large subunit of a ribosome as shown (the light gray area is the large subunit, while the black shape is the drug). From this information you can conclude that chloramphenicol.. prevents transcription in prokaryotes. prevents translation in prokaryotes. prevents mRNA-ribosome binding. prevents translation in eukaryotes. prevents transcription in eukaryotes.

prevents translation in prokaryotes.

Ribosomes contain which of the following? tRNA mRNA, tRNA, and rRNA are all found as part of the ribosome. rRNA mRNA

rRNA

Mice that are injected with only the R strain of Streptococcus pneumoniae? -are killed, because R strain cells are deadly. -stay healthy, because their immune systems can kill this strain easily. -become sick for prolonged periods of time.

stay healthy, because their immune systems can kill this strain easily

Which of the following is involved in bringing amino acids to the ribosomes? tRNA rRNA mRNA mRNA, tRNA, and rRNA are all involved in transporting amino acids to the ribosomes.

tRNA