Exam 2 Flashcards by Sonjia Wortham

The phylogenetic classification of bacteria is based on

rRNA sequences

How well did you know this?

Not at all

Perfectly

In the scientific name Vibrio cholera, Vibrio is the

genus

How well did you know this?

Not at all

Perfectly

You discovered a unicellular organism that lacks a nucleus. You suspect the organism is in the group

bacteria

How well did you know this?

Not at all

Perfectly

Into which group would you place a photosynthetic organism that lacks a nucleus and has a thin peptidoglycan wall surrounded by an outer membrane?

gram-negative bacteria

How well did you know this?

Not at all

Perfectly

Which of the following best describes the enteric bacteria (a bacterial group found primarily in the intestines of humans)?

facultatively anaerobic gram-negative rods

How well did you know this?

Not at all

Perfectly

Which of the following bacteria is gram-negative?

Escherichia

How well did you know this?

Not at all

Perfectly

Which of the following is not correct regarding Escherichia coli?

doesn’t require or use O2, but can tolerate it

How well did you know this?

Not at all

Perfectly

Which of the following genera include bacteria with stalks?

Caulobacter

How well did you know this?

Not at all

Perfectly

Which of the following have their flagella (sometimes called axial filaments) located entirely between the cytoplasmic membrane and the outer membrane?

spirochetes

How well did you know this?

Not at all

Perfectly

Cyanobacteria

produce O2

How well did you know this?

Not at all

Perfectly

Bacteria that naturally exhibit bioluminescence have been found in which of the following genera?

Vibrio

How well did you know this?

Not at all

Perfectly

Bacterial sensing of cell density is called:

quorum sensing

How well did you know this?

Not at all

Perfectly

Which of the following statements about the causative agent of Rocky Mountain spotted fever is FALSE?

It is gram-positive

How well did you know this?

Not at all

Perfectly

Bacteria of the genus Bdellovibrio:

prey on Gram-negative bacteria

How well did you know this?

Not at all

Perfectly

In which of the following regions in the host bacterium are you most likely to find Bdellovibrio?

periplasm

How well did you know this?

Not at all

Perfectly

Members of the genus Neisseria cause which of the following human diseases?

Gonorrhea

How well did you know this?

Not at all

Perfectly

Members of the genus Rhizobium:

grow symbiotically in root nodules of legumes where they fix nitrogen

How well did you know this?

Not at all

Perfectly

Bacteria that can perform both nitrogen fixation and oxygenic photosynthesis:

Cyanobacteria

How well did you know this?

Not at all

Perfectly

Which genus contains anaerobic endospore formers?

Clostridium

How well did you know this?

Not at all

Perfectly

Bacilli are:

Gram-positive, aerobic, spore forming rods

How well did you know this?

Not at all

Perfectly

Bacillus thuringiensis:

is used as a biological insecticide

How well did you know this?

Not at all

Perfectly

Staphylococcus and Streptococcus can usually be differentiated by microscope examination because of:

cell arrangement

How well did you know this?

Not at all

Perfectly

The characteristic most notable regarding the Mycoplasmas is that they:

lack peptidoglycan

How well did you know this?

Not at all

Perfectly

The characteristic most notable regarding the Mycobacteria is that they:

have unusual outer membrane, made of unusual lipids

How well did you know this?

Not at all

Perfectly

Which of the following bacteria produce mycelia?

Streptomyces

Streptomyces are important because they:

make antibiotics

Gram-positive bacteria that form symbiotic association with roots of woody plants and can fix atmospheric nitrogen:

Frankia species

Saccharomyces cerevisiae are often nicknamed:

baker’s yeast, budding east , and brewer’s yeast

Plasmodium falciparum, that causes malaria is a/an:

eukaryote

African sleeping sickness is caused by:

Trypanosoma brucei

Which of the following are NOT eukaryotes?

Candida, Entamoeba, Giardia, and Trypanosoma are all eukaryotes

T/F Most bacteria reproduce by binary fission.

true

Microorganisms are at their most uniform in terms of chemical and physiological properties during this growth phase:

exponential

Which of the following are a reason(s) for the decline in cell numbers during the death phase?

Accumulation of toxic waste materials, and Depletion of nutrients and O2

If bacteria have a doubling time of 20 min and you start with two bacterial cells, how many cells will you have after 1 hour?

Which of the following is an advantage of the standard plate count?

determines the number of viable cells

Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many viable and culturable cells were in the original sample?

36 per milliliter

A microbiologist is testing the drinking water for a municipality. What would be the best method for testing the purified water?

membrane filtration

T/F Thermophiles prefer to grow at high temperatures.

true

Most bacteria grow best at pH:

The term aerotolerant anaerobe refers to an organism that:

does not use oxygen but tolerates it

T/F Enzyme catalase protects the cells from toxic forms of oxygen.

true

A culture medium consisting of agar, peptone, and beef heart extract is a:

complex medium

T/F An isolated colony on a streak plate contains millions (or even billions) of identical cells all arising from one initial cell.

true

The sugar found in DNA is:

deoxyribose

If 20% of nucleotides in the DNA of a particular organism contain thymine, estimate the percentage of cytosine that is present in the DNA.

30%

Which of the following is not a complementary base pair found in DNA molecules?

Adenine-Uracil

Each chromosome has one or more site(s) where replication begins.

origin

During replication, which enzyme unwinds the two strands of the DNA molecule from one another?

Helicase

An enzyme that makes covalent bonds between Okazaki fragments in the lagging strand of DNA being replicated is:

DNA ligase

During DNA replication, the template sequence 3’-ATGGCTT -5’ will direct the synthesis of what sequence:

5’-TACCGAA -3’

Which of the following statements is FALSE?

DNA replication proceeds in only one direction around the bacterial chromosome

Which of the following nitrogenous bases is found in RNA but not in DNA?

Uracil

T/F Genes code for proteins only.

false

T/F To start the synthesis RNA polymerase requires a primer.

false

RNA polymerases require which of the following elements to transcribe DNA?

DNA template, ribonucleotides

Which of the following is NOT a product of transcription?

a new strand of DNA

T/F During transcription, RNA pol joins ribonucleotides in 3’ to 5’ direction?

false

A bacterial __________ is the non-transcribed region of the DNA to which RNA polymerase binds to initiate transcription.

promoter

Coding sequence of the gene is 5’ AAA TCG GGC GTA CCT 3’. What will be the sequence of the corresponding mRNA?

5’AAA UCG GGC CUA CCU 3’

The genetic code is translated in groups of how many bases?

three

The genetic code is said to be __________ because more than one codon will specify a particular amino acid.

degenerate

The portion of the tRNA molecule that forms hydrogen bonds with the codon on the mRNA is called the:

anticodon

Which molecules deliver amino acids to ribosomes during translation?

a.a.tRNA

For translation the start codon is often 1 which codes for 2 :

1-AUG, 2-methionine

Peptide bonds between amino acids are formed in which process?

translation

How many different termination codons (stop codons) are used in translation?

T/F In eukaryotes gene expression is always “coupled” (i.e. transcription and translation occur at the same time and place in the cell).

false

In eukaryotes pre-mRNA is much longer than the mRNA that eventually be translated. This can be explained by which of the following?

Introns have not yet been removed from the transcript

Gene expression regulation can occur at which steps:

translation and transcription

Genes that are expressed at a constant level all the time are said to be:

constitutive

Operons are found in the cells of which of the following types of organisms?

prokaryotes

When a repressor binds to the operator site on the DNA it normally _________.

inhibits the initiation of transcription

__________ activate repressor proteins, thereby decreasing the synthesis of certain enzymes.

Corepressors

__________ alter repressor proteins thereby increasing the rate of transcription initiation.

Inducers

When the catabolite activator protein (CAP) binds to its binding site in DNA, it _________.

promotes the RNA polymerase binding to the promoter

E.coli LacZ gene, which codes for the enzyme beta-galactosidase, is in the Lac operon. E. coli cells exposed to which of the following conditions would produce the highest amount of beta-galactosidase?

lactose is present, and glucose is absent

An example of repressible operon is:

Trp operon

Which is false regarding the two-component regulatory system in bacteria?

The sensor kinase is phosphorylated by the response regulator when the extracellular environment changes

T/F Mutation is defined as a change in cell’s phenotype.

false

A __________ mutation does not alter the amino acid sequence of the resulting protein.

silent

A __________ mutation is one that causes premature termination of the synthesis of the protein product.

nonsense

Conjugation is the transfer of DNA from a donor to a recipient cell:

by cell-to-cell contact via sex pili

T/F Transformation is the transfer of DNA to donor cells by bacteriophage.

false

Transduction requires a(n) ________ to move DNA from one bacterial cell to another.

bacteriophage

T/F Transduction is an example of vertical DNA transfer.

False

T/F In recombinant DNA technology, a vector is a self-replicating DNA, such as a plasmid.

true

T/F Restriction enzymes catalyze the hydrolysis of phosphodiester bonds of a DNA at a specific site.

true

In cloning, the enzyme that joins the DNA fragments together is:

ligase

You have a small gene that you wish to amplify by PCR. After 4 replication cycles, how many double-stranded DNA molecules do you have if you started with a single molecule?

What happens during the Denaturing step of PCR?

The double-stranded DNA is separated into two single strands of DNA

If the primer sequence for PCR is 5'-TCG-3', what sequence of DNA will it anneal to?

3'-AGC-5'