Exam 2 Micro

which one of the following is not a physical factor that affects the growth rate of cells?

Nutrient concentration

what term applies to a microbe that can synthesize all of its cellular constituents from a simple carbon source and inorganic salts?

prototroph

The enzyme catalase is used to detoxify which harmful oxygen species?

hydrogen peroxide

What is the term for microbes that grow optimally at a pH below 5.5?

acidophiles

What is the term for microbes that grow optimally at very high salt concentrations?

Halophiles

You identify a microbe that grows poorly under regular atmospheric conditions but well in animal tissues. To what group does this microbe likely belong?

microaerophile

Which medium is used to allow some microbes to grow while suppressing others?

selective

Which medium is used to allow some microbes on a plate to be distinguished from others?

differential

Which medium is used to allow slow-growing microbes to gain a competitive growth advantage?

enrichment

Which of these methods can be used to obtain a viable cell count?

plate counts of serial dilutions

What would you use to measure the optical density of a bacterial culture?

a spectrophotometer

If a cell culture contains 400 cells/ml at time = 0 and it has a generation time of 30 minutes, how many cells (cells/ml) will be present after 2 hours of incubation?

6400 cells/ml

In which phase of the growth curve does preparation for cell division and synthesis of enzymes needed for catabolic activity take place?

lag phase

Which is the best definition of an antiseptic?

a chemical agent that is applied to living tissue to kill and inhibit microbes.

Generation time is the average time it takes an actively growing cell in a population to divide.

True

What is the term for the primary pathway for fatty acid oxidation?

B-oxidation pathway

What are enzymes that break down proteins?

proteases

What is/ are the products(s) of the light reactions of photosynthesis?

ATP & NADPH

Where is the reaction center of photosystems located?

Within a biological membrane

Some anoxygenic photosynthetic bacteria are able to use _______ as an electron source.

H2S

Cyanobacteria use _______ as an electron source for the reduction of NADP+.

water

How would the "dark reactions" of photosynthesis best be described?

carbon dioxide fixing reactions

Nitrogen fixation is the reduction of _______ to ammonia for cell use.

dinitrogen

The biosynthesis of amino acids requires starting intermediates from which of these pathways?

glycolysis, TCA cycle, & the pentose phosphate pathway

The most common lipids in the cell are synthesized from ___________ and ____________.

fatty acids & glycerol

The B-oxidation pathway is used for the breakdown of nucleotides for use as a carbon source.

False

Most cells prefer to assimilate nitrogen as ammonia

True

The assimilation of sulfate requires energy

True

The Watson-Crick model of DNA shows the base adenine pairs with

thymine, while cytosine pairs with guanine

The main difference between Bacteria and Archaea chromosomal DNA when compared to Eukarya chromosomal DNA is that Bacteria or Archaea chromosome usually

is circular, while Eukarya is linear

Replication of the bacterial chromosome typically begins at how many locations?

1 (one)

In bacteria, what is the first protein to bind to the oriC region of the DNA molecule to start the replication process?

DnaA

After the DNA is unwound at the site of DNA replication, what binds to the unwound DNA to prevent it from reannealing?

single stranded DNA binding proteins

Which statement below is FALSE regarding replication of the bacterial chromosome?

The leading strand is replicated in the 5' to 3' direction and the lagging strand in the 3' to 5' direction.

Which enzyme removes the RNA primer and fills the gap during DNA replication in bacteria?

DNA polymerase I

Replication termination in E. coli involves which two proteins?

Tus protein and topoisomerase II

What is the term for a special sequence at the end of the chromosome in eukaryal cells?

Telomere

Which enzyme is responsible for adding the final bases to the end of a chromosome during DNA replication in eukaryal cells?

telomerase

Which of the best differentiates DNA and RNA?

RNA usually is single stranded, and DNA usually is double stranded; RNA contains ribose and DNA contains deoxyribose, and RNA contains the base uracil in place of thymine, which is in DNA

A gene can best be described as a segment of DNA that:

is transcribed

The DNA replication process in Archaea more closely resembles that in Eukarya than in Bacteria.

True

In DNA replication, nucleotides are always added in the 5' to 3' direction.

True

Replication of eukaryal DNA requires RNA primer synthesis.

True

In the same bacterial cell, different sigma factors are able to control the expression of large blocks of genes.

True

Basic proteins that help to package the DNA in eukaryal cells are called

histones

For the initiation of transcription in bacteria, RNA polymerase binds to what region on the DNA?

Promoter

What is the sigma factor of the RNA polymerase holoenzyme responsible for?

recognition of the promoter region

Most bacterial promoters consist of two regions: __________ and ___________.

Pribnow box; -35 region

What does Rho-independent termination of transcription in bacteria involve?

The formation of a hairpin loop followed by a poly U sequence

Transcription termination in eukaryal cells is more complex than in bacterial cells as the RNA molecule undergoes further processing before becoming a functional mRNA. Which of these BEST describes this processing?

Capping the 5' end with 7-methyl guanosine, adding a poly-A sequence at the 3' end, and removing internal sequences called introns

Initiation of translation in bacteria starts with the binding of the 30S ribosomal subunit to the mRNA molecule. The ribosomal binding site is nearer the _________ end of the mRNA molecule and is called the ________.

5'; Shine-Dalgarno sequence

The mRNA of bacterial cells is often polycistronic. What does this term mean?

it contains the code for multiple peptides

The RNA polymerase in Archaea is more similar to Bacteria RNA polymerase than Eukarya RNA polymerase II

False

The site on the DNA molecule that is recognized by the sigma subunit of the RNA polymerase for binding to start transcription is called the _________.

Promoter

The -10 element of the bacterial promoter is also referred to as the

Pribnow box

The Shine-Dalgarno sequence on a mRNA is recognized by the __________ of the 30S ribosome

16S rRNA

Viral genomes may consist of which of these molecules?

Double-stranded RNA; Double-stranded DNA; Single-stranded RNA; Single-stranded DNA; All choices correct

What is the viral capsid composed of?

Protein

What protective structure contains the viral nucleic acid?

Capsid

What is the most common way for non-enveloped viruses to enter animal cells?

Through endocytosis of the virion

What is the most common way for enveloped viruses to enter animal cells?

By the virion fusing with the plasma membrane

How do bacteriophages invade bacterial cells?

By the bacteriophage injecting its nucleic acid

Which choice best explains the lack of enveloped viruses infecting plants and bacteria?

The cell walls of plants and bacteria would prevent budding from occurring

What technique is usually used for the quantification of a bacteriophage suspension?

A plaque assay

Which Domain contains the viruses?

They aren't classified at the domain level

In Mad cow disease, prions act in which of the following ways?

PrPᶜ is converted to PrPˢᶜ

Viroids are infectious RNA particles that cause infections in

Plants

What is a prion?

An infectious protein particle

How do prions cause disease?

By causing naturally occurring proteins in the cell to change shape

Gene therapy technologies may use viruses

As gene-carrying vectors for delivery to target cells

Enveloped viruses acquire their envelope from host cell membranes. T/F

True

The zone of clearing as a result of a phage infection on a lawn of E. coli growing on the surface of an agar plate is called a/an ______________

Plaque

Most likely, "host specificity" of a virus is determined by

Interactions between viral attachment proteins and host cell receptors

A non-enveloped virus will have its attachment proteins present in its

Capsid spikes

The second step in viral replication is entry. For bacteriophage, entry usually involves

Direct entry of the nucleic acids into the cell

The influenza virus gains entry into a host cell by

Receptor-mediated endocytosis

The influenza virus gains entry into a host cell by an endocytotic process. The viral nucleocapsid leaves the endosome and enters the cytoplasm through a membrane fusion mechanism. Fusion of the viral envelope with the endosomal membrane is facilitated by

A conformational change in the hemagglutinin to expose a fusion protein

Most non-enveloped animal viruses enter the host cell by

Receptor-mediated endocytosis

Plant viruses often gain entry into host cells by

Injury caused by insects to host cells

The Baltimore classification scheme for viruses divides all viruses into seven groups based on

How they produce mRNA and replicate their genome

The Baltimore classification scheme classifies viruses based on their mechanism of mRNA and genome synthesis. Using this classification scheme, all viruses are placed into one of ________ classes.

seven

Most enveloped viruses exit the cell by

Budding

Most non-enveloped viruses exit the cell by

Cell lysis

Most enveloped viruses exit the host cell through cell lysis. T/F

False

HIV enters the cell through a/an _________ mechanism.

Membrane fusion

The quiescent phage genome, whether it exists as a plasmid or integrated into the host genome, is referred to as a

Prophage

A cell containing a prophage is called a

Lysogen

Initiation of translation in bacteria starts with the binding of the 30S ribosomal subunit to the mRNA molecule. The ribosomal binding site is nearer the _____ end of the mRNA molecule and is called the _____.

5′ end; Shine-Dalgarno sequence

After the translational process, the polypeptide folds into the appropriate conformation for proper functioning. What group of proteins aids in protein folding?

Chaperones (chaperonins)

Which of these would a signal peptide be used for?

To move a protein to the outside of the cell

Which of these is a term for a point mutation that results in a change in the amino acid specificity of the codon?

Missense

Which of these is a point mutation that results in changing a codon from an amino acid codon to a stop codon?

Nonsense

Which of these results from a deletion of base pairs such that the amino acid sequence is disrupted from that point downward?

Frameshift mutation

All living organisms use the same genetic code for the translation of mRNA

True

Which of the following does a tRNA interact? (Select all that apply)

Codon

Ribosome

DNA

mRNA

Amino Acid

✔️ Codon (via its anticodon)

✔️ Ribosome

✔️ mRNA

✔️ Amino Acid

Which of the following correctly describes the genetic code?

The codon, AUG, usually serves as the start codon.

It consists of codons made up of RNA.

All organisms share the same genetic code.

Identify the similarities in translation between Bacteria and Eukarya?

The codon, AUG, usually serves as the start codon.

Chaperonins help facilitate protein folding.

Sixty-one codons code for the 20 amino acids commonly found in proteins.

Which of these is a term for when a segment of a chromosome breaks off and reattaches to a different chromosome or a different location within the same chromosome?

Translocation

Which of these is a term for when DNA literally are flipped around and reinserted into the genome at the same location?

Inversion

Which of these is the result of ionizing radiation?

Double-stranded DNA break