BIOL 3301 Exam 1

The morphology of a cell influences its

A) motility

B) metabolism

C) surface-to-volume ratio

D) motility and surface-to-volume ratio

motility and surface-to-volume ratio

Compared to eukaryotes, bacteria and archaea have _____ S/V ratios, causing _____ nutrient exchange.

A) lower / lower

B) lower / higher

C) higher / lower

D) higher / higher

higher / higher

The use of the gram stain in microbiology is important because it differentiates

A) Bacteria from Archaea

B) prokaryotic cells from eukaryotic cells

C) bacterial cells with different types of cell walls

D) archaeal cells with different types of metabolism

bacterial cells with different types of cell walls

You have discovered a new coccoid-shaped microorganism with no nucleus, a rigid cell wall, and a diameter of 2 micrometers. Chemical tests reveal that its cell wall does not contain peptidoglycan but pseudomurein. The new microorganism is:

A) most likely a bacterium

B) most likely a eukaryote

C) most likely an archaeon

D) either a bacterium or an archaeon

most likely an archaeon

When does endospore formation commence?

A) when bacterial growth ceases due to the limitation of an essential nutrient

B) when the bacterium is undergoing binary fission

C) when bacteria are dividing exponentially

D) following bacterial death

when bacterial growth ceases due to limitation of an essential nutrient

The cell membrane of microbes is associated with:

A) Nutrient uptake

B) killing of competing microbes

C) lipid production

D) Permeability of molecules, proteins anchored on it, and a chemiosmotic gradient driving the ETC

Permeability of molecules, proteins anchored on it, and a chemiosmotic gradient driving the ETC.

Which of the following structures is primarily involved in the attachment of bacteria to surfaces or host cells?

A) Flagella

B) Fimbriae

C) Pili

D) Endospores

fimbriae

A microbial cell’s membrane is considered _____, because its internal constituents are maintained within the cell. However, it also imports and exports other molecules in response to its environment.

A) differential

B) microselective

C) rigid

D) semipermeable

semipermeable

The production of human proteins (e.g. insulin) by genetically engineered microorganisms is an example of _______, a subdiscipline of microbiology

A) applied microbiology

B) biotechnology

C) molecular microbiology

biotechnology

Archaea and bacteria are unified as prokaryotes in lacking ______, which eukaryotes contain, such as mitochondria

A) membranes

B) nuclei

C) membrane-enclosed organelles

D) nuclei and membrane bound organelles

nuclei and membrane bound organelles

Which is an example of a micronutrient?

A) arginine

B) inorganic phosphorous

C) iron

D) vitamin B12

iron

Activation energy is the energy

A) required for a chemical reaction to begin

B) given off as the products in a chemical reaction are formed

C) absorbed as delta G moves from negative to positive

D) needed by an enzyme to catalyze a reaction without coenzymes

required for a chemical reaction to begin

If an oxidation reaction occurs

A) simultaneous reduction of a different compound will also occur, because electrons do not generally exist alone in solution

B) another oxidation reaction will occur for a complete reaction, because one oxidation event is considered a half reaction

C) a cell is undergoing aerobic respiration, because oxygen is being used

D) a reduction reaction would not occur, because they are opposite reaction mechanisms

simultaneous reduction of a different compound will also occur, because electrons do not generally exist alone in solution

In aerobic respiration, the final electron receptor is

A) hydrogen

B) oxygen

C) water

D) ATP

oxygen

Which metabolic strategy does NOT invoke the proton motive force for energy conservation?

A) aerobic catabolism

B) fermentation

C) chemoorganotrophy

D) photoautotrophy

fermentation

AT-rich DNA with denature/melt

A) at a higher temperature than GC-rich DNA

B) at a lower temperature than GC-rich DNA

C) usually at the same temperature as GC-rich DNA, with some minor variations

D) in accordance with the animal or plant from which it was taken

at a lower temperature than GC-rich DNA

Supercoiling is important for DNA structure, because

A) it holds together the antiparallel strands of DNA in the double helix

B) it provides energy for transcription

C) it condenses the DNA so that it can fit inside a cell

D) it prevents RNA from pairing with DNA in the double helix

it condenses the DNA so that it can fit inside the cell

An operon is a useful genetic element, because it

A) encourages the binding of RNA polymerase

B) allows coordinated expression of multiple related genes in prokaryotes

C) translates DNA sequence into amino acid sequence

D) encourages the binding of ribosomes in the correct location

allows coordinated expression of multiple related genes in prokaryotes

Transposable elements are

A) segments of DNA that move from one site to another

B) transcribed genes

C) segments of RNA that are involves in transposing DNA into proteins

D) proteins that aid in the secretion of enzymes out of the cell

segments of DNA that move from one site to another

Plasmids often encode for proteins

A) involved in translation

B) required for cellular growth

C) that confer resistance to antibiotics

D) involved in DNA replication

that confer resistance to antibiotics

Consider a mutation in which the change is from UAC to UAU. Both codons specify the amino acid tyrosine. Which type of point mutation is this?

A) silent mutation

B) nonsense mutation

C) missense mutation

D) frameshift mutation

silent mutation

The mutagens 2-aminopurine and 5-bromouracil are examples of

A) alkylating agents

B) nucleotide base analogs

C) chemicals reacting with DNA

D) None of the above

nucleotide base analogs

The SOS regulatory system is activated by

A) the activity of DNA polymerase IV

B) DNA damage

C) transcription of LexA

D) repression of RecA

DNA damage

Mutation rates are similar in bacteria and archaea, yet under certain stressful conditions mutation rates increase. Why is the mutation rate not constant and close to zero all of the time?

A) Increased mutation rates can be advantageous in rapidly changing environments because some random mutations may be useful for survival

B) Microorganisms carefully control the mutation rate of their DNA to match the environmental conditions and maximize evolution

C) The increased mutation rate under stressful conditions is an indication that the microorganisms can no longer replicate their DNA properly and are about to die

D) Constant mutation rates would halt evolution completely

Increased mutation rates can be advantageous in rapidly changing environments because some random mutations may be useful for survival

During a laboratory experiment, a microbiologist observed that a bacterial population has acquired resistant to an antibiotic it was previously susceptible to. The scientist notes that this population was cultures in an environment containing both antibiotic-resistant donor cells capable of conjugation and bacteriophages known for transducing antibiotic resistance genes.

Which of the following conclusions is supported by the observation that the non-resistant bacteria gained antibiotic resistance?

A) the antibiotic itself induced mutations in the bacterial genome, leading to resistance

B) bacteriophages facilitated the transfer of resistance genes from donor cells to recipient cells, demonstrating transduction

C) direct cell-to-cell contact between donor and recipient cells allowed for the transfer of antibiotic resistance genes, indicating conjugation occurred.

D) both B and C are plausible

Both B (transduction via bacteriophages) and C (conjugation) are plausible explanations for the observed acquisition of antibiotic resistance, showcasing the roles of conjugation and transduction in gene transfer.

tRNA molecules

A) function to transfer ribonucleotides to RNA polymerase during transcription

B) function to transfer the correct amino acids to the ribosome during translation

C) contain codons that bind to ribosomes during translation

D) are only present in the nucleus of eukaryotes

function to transfer the correct amino acids to the ribosome during translation

An Hfr cell is known for its role in transferring parts of its chromosomal DNA to recipient cells during conjugation. Considering an Hfr strain that carries a gene for a novel metabolic pathway on its chromosome, which of the following outcomes would most likely contribute to increased genetic variability in the bacterial population?

A) The Hfr cell loses its ability to produce the pilus, preventing any DNA transfer

B) The recipient cell acquires the novel metabolic pathway gene and expresses it, enhancing its survival and reproduction in varied environmental conditions.

C) The transferred DNA from the Hfr cell is degraded by the recipient cell’s restriction enzymes, leaving its genome unchanged

D) All recipient cells become Hfr cells after acquiring the F factor, but do not integrate the novel metabolic pathway gene into their chromosomes

The recipient cell acquires the novel metabolic pathway gene and expresses it, enhancing its survival and reproduction in varied environmental conditions.

Which of the following is an example of one codon?

A) CATT

B) GCCATT

C) CAG

D) CCGUAA

CAG

You experimentally change the DNA sequence directly upstream of a start codon of an operon in E.coli to investigate the function of this region of DNA. Analysis reveals that after the change the same amount of mRNA is made from the operon, but there are very few proteins made from the operon. What is the most likely function of the DNA sequence that you changed?

The DNA sequence likely functions as

A) a ribosome binding site

B) a promoter

C) a termination sequence

D) in transcriptional regulation

The DNA sequence likely functions as a ribosome binding site

You are studying a protein in Salmonella typhimurium that you believe is a toxin. Whenever you attempt to purify the protein from lysed cell cultures, you get two forms of the protein. One form is smaller than the other and is missing 15 amino acids from the N-terminus compared to the larger form. This leads you to hypothesize that:

A) there are two termination sites in the mRNA

B) the protein requires chaperonins to fold properly

C) the protein is secreted and folds outside of the cell

D) you need to re-do the experiment because there should only be one form

the protein is secreted and folds outside of the cell.

Consider the following experiment. First, large populations of two mutant strains of E.coli are mixed, each requiring a different, single amino acid. After plating them onto a minimal medium, 45 colonies grew. Which of the following may explain this result?

A) the colonies may be due to back mutation (reversion)

B) the colonies may be due to recombination

C) either A or B is possible

D) neither A nor B is possible

Either A (colonies due to reversion / back mutation) or B (recombination) are possible.

A deleterious mutation in recA results in

A) a decrease in specific recombination

B) a decrease in homologous recombination

C) an increase in homologous recombination

D) no change in either general or specific recombination

a decrease in homologous recombination

Consider conjugation in E.coli. In which of the following matings would chromosomal genes be transferred most frequently?

A) F+ x F-

B) F- x F-

C) Hfr x F-

D) F+ x F+

Hfr x F-

Which of the following features are common to transformation, transduction, and conjugation?

(1) unidirectional transfer of genes

(2) incomplete gene transfer

(3) homologous recombination

(4) meiosis occurring in the recipient

A) 1, 2, 3

B) 1, 2

C) 3, 4

D) 1, 2, 4

1, 2, 3

Which of the following is most similar to lysogeny?

A) Hfr state

B) F+ state

C) F- state

D) F’ state

Hfr state