Microbiology EXAM ONE (CH. 1-6 HW)

Short, bristle-like structures that extrude from the surface of a prokaryotic cell are called

fimbriae

Which does not describe eukaryotic flagella? flagellin protein plasma membrane-enclosed whip-like motion 9+2 arrangement of microtubules anchored by a basal body connected to a centriole

flagellin protein

You have isolated a new organism which has eukaryotic cells, is multicellular, grows as hyphae, does not perform photosynthesis, and has a cell wall. This organism most likely belongs to which kingdom?

fungi

Prokaryotic cells house a single circular chromosome in their __________.

nucleoid region

What does the plaque assay determine?

number of bacteriophage in a sample Submit

Why are most prokaryotic cells small?

nutrient diffusion is more efficient for smaller cells

Which of the following is a valid difference between the leading and lagging strands in DNA replication?

on the leading strand, only a single RNA primer is needed to initiate continuous DNA synthesis.

Bacteria with flagella distributed all over the cell surface are described as having:

peritrichous flagella

You observe that when you grow Serratia marcescens at human body temperature, the resulting bacterial colonies appear white. However, when you grow the same bacterium at room temperature, the colonies that grow are red. This difference in pigmentation is best described as a ____________.

phenotype difference

Which of the structure allows bacteria to transfer genetic information through conjugation?

pili

You have isolated a new eukaryotic organism which is unicellular and performs photosynthesis. The organism is most likely classified as a(n)

plant-like protist

Which of the following would not move freely across the cytoplasmic membrane?

positively charged hydrogen ions

Which of the following are contributors to viral genome evolution? quick replication time and superior proofreading by RNA polymerases compared to DNA polymerasessuperior proofreading by RNA polymerases compared to DNA polymerasesquick replication timethe large number of virions released within a hostquick replication time and the large number of virions released within a host

quick replication time and the large number of virions released within a host

Which grouping of parasitic helminths includes hookworms? View Available Hint(s) Flukes Cestodes Roundworms Flatworms

roundworms

Which is not a cancer linked to a specific virus?

skin cancer (UV)

Oncogenic viruses

stimulate uncontrolled host cell division.

Considering the process of osmosis, what will occur if a bacterial cell is put into a hypotonic solution?

the cell will take on water and lyse if the cell wall is damaged

The rough ER and the smooth ER are distinguished from each other by

the presence or absence of membrane-bound ribosomes.

The rabies virus primarily affects the nervous system. The specificity that the rabies virus has for neuronal host cells is primarily dictated by __________________________.

the spikes that protrude from its viral envelope

Viruses are considered to be non-living pathogens for which reason?

their lack of metabolic processes

Which property is not used to classify viruses?

tissue types infected

Why are chemical agents like lysozyme more likely to damage Gram-positive bacteria than Gram-negative bacteria?

Gram-negative bacteria have an outer membrane as part of their cell wall.

Which of the following is not needed to carry out excision repair in Escherichia coli? View Available Hint(s) Excision complex DNA ligase DNA polymerase I Helicase

HELICASE

HIV, the virus which causes AIDS, interacts with two receptors on the host cell membrane: CD4 and CCR5. A small percentage of individuals have a genetic mutation which causes their cells to lack CCR5. These individuals will never develop AIDS nor are they able to pass HIV on to others. Which part of viral replication is being blocked by the lack of a receptor?

HIV cannot attach to the host cell without the proper membrane recepto

A young patient who underwent surgical placement of depth electrodes for epilepsy treatment contracted a prion disease. Cortical electrode probes are known to be reused in patients. Based on this information, which of the following prion diseases did the young patient most likely contract?

Iatrogenic Creutzfeldt-Jakob Disease

_____________ is a type of sexual reproduction that occurs in eukaryotes and results in four genetically unique haploid daughter cells.

Meiosis

Which of the following statements about mutations is false? Multicellular organisms evolve faster than unicellular organisms. A mutation in a single-celled organism is more likely to be passed to daughter cells than a multicellular organism. Mutations are essential to variation within species. Mutations are essential to evolution within species. A mutation is a change in the genetic material of a cell or virus.

Multicellular organisms evolve faster than unicellular organisms.

An individual uses an in-home test kit one week after engaging in high-risk behavior for HIV infection. The test kit uses a saliva sample that is mailed to a lab where an agglutination test to detected HIV antibodies is run. The results come back negative for HIV. What should the patient consider regarding these test results?

One week may not be enough time for HIV antibodies to be detected.

A nurse experienced an accidental needle stick while treating a patient who has hepatitis C. The seroconversion window for hepatitis C is approximately 6-8 weeks. Given this information, which of the following viral detection methods would be most appropriate for detecting a hepatitis C infection in the nurse one week following the needle stick?

PCR-based detection of hepatitis C RNA

Choose the statement which best defines a pleomorphic organism. View Available Hint(s) Pleomorphic organisms lack the ability to take on different forms such as shape or arrangement. Pleomorphic organisms can alter their size but not their shape. Pleomorphic organisms can take on different forms, which enhances their survival and transmission to a human host. Pleomorphic organisms do not impact an organism's ability to form a biofilm.

Pleomorphic organisms can take on different forms, which enhances their survival and transmission to a human host.

chromatin is

The combination of DNA and proteins that make up the chromosome

RNA is distinguished from DNA because only RNA:

Typically exists as a single-stranded molecule

nonspecific permeases

allow a variety of molecules to cross the cytoplasmic membrane.

viral spikes

allow the virus to attach and enter host cells, may be a target for the host immune system, and show specificity in binding to particular structures on the host cell

Which stage of animal virus replication may be blocked by a drug that binds with the viral spike?

attachment

In the Spring of 2009, a novel H1N1 virus emerged that had a new combination of genes from pigs, humans, and birds. As a result, the virus spread quickly, resulting in a swine flu pandemic. Which of the following concepts explains why the outbreak occurred?

(FAST) Antigenic shift

Which direction are phosphodiester bonds of DNA usually built in?

5'-3'

Which description of antigenic drift and antigenic shift in the influenza virus is incorrectly matched? Antigenic drift: A host vaccinated against an influenza strain before antigenic drift may lack effective immunity and be susceptible to infection.Antigenic drift: Spontaneous mutation leads to a minor change in HA or NA spikes.Antigenic shift: Often leads to viral strains with new features such as increased infectivity or expanded host range.Antigenic shift: May result in a pandemic outbreak due to widespread lack of immunity.Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans.

Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans.

Which of the following statements is false about quorum sensing? Quorum sensing allows unicellular organisms to coordinate their processes. Coordinated protein synthesis through quorum sensing is the foundation for forming biofilms. Bacteria can communicate using chemical messengers called autoinducers. Bacteria that experience quorum sensing have a decreased chance of survival. Quorum sensing allows bacteria to alter their protein synthesis in response to changes in population density.

Bacteria that experience quorum sensing have a decreased chance of survival.

A patient presents with symptoms of severe gastrointestinal distress. Bacterial and viral pathogens are ruled out. A protozoan which moves via hair-like appendages is observed upon microscopic examination of the patient's stool. The most likely cause of the infection is

Balantidium coli, a ciliated protozoan.

Which statement is not true about the virus capsid? The capsid functions as a package for the viral genetic material.Both bacteriophage and animal viruses have capsids.Because the capsid is not essential to the virus, it is not a useful target for antiviral drugs.The capsid is made of one or more types of protein subunits.The capsid determines the shape of the virus.

Because the capsid is not essential to the virus, it is not a useful target for antiviral drugs.

Which statement is not true about eukaryotic ribosomes? Both bound and free ribosomes consist of a 40S and a 60S subunit. Ribosomes found in mitochondria are 70S rather than the 80S type found in the cytoplasm. Bound ribosomes are attached to the endoplasmic reticulum (ER). Bound ribosomes produce proteins that are destined for secretion from the cell. Bound ribosomes are always bound while free ribosomes are always free.

Bound ribosomes are always bound while free ribosomes are always free.

Which of the following does not represent a shape or arrangement that a prokaryote can assume? View Available Hint(s) Clusters of bacilli form a Pallisade arrangement. Stella are star shaped cells. Clusters of bacilli form a Staph arrangement. Vibrio are comma shaped cells.

Clusters of bacilli form a Staph arrangement.

Which of the following statements about constitutive genes is false? Constitutive genes are referred to as housekeeping genes. Constitutive genes function differently than facultative genes. Constitutive genes produce their proteins when a cell encounters a specific environmental change. Constitutive genes account for less than 20 percent of a cell's genes. Constitutive genes are expressed at any given time.

Constitutive genes produce their proteins when a cell encounters a specific environmental change.

Choose the false statement about cellular transport mechanisms. View Available Hint(s) Active transport requires energy and uses carrier proteins to move substances against their concentration gradient. Osmosis is the passive movement of water from a low-solute concentration to a high-solute concentration. Facilitated diffusion does not require energy and uses membrane proteins to move substances down their concentration gradient. Diffusion is the passive movement of substances from areas of low concentration to areas of high concentration.

Diffusion is the passive movement of substances from areas of low concentration to areas of high concentration.

Which of the following is an unsuitable culture method for an animal virus?

Direct inoculation of virus onto blood agar

An elderly patient who contracted chickenpox as a child now has shingles as an adult. You explain to your patient that both diseases are caused by the same virus, which lays dormant in the body prior to reactivation. Based on this information, choose the true statement.

During dormant periods, the virus exists episomally inside of infected host cells.

Which of the following statements about plasmids is false? Molecular biologists often use plasmids to generate cell lines that make useful products for medical applications. Plasmids are easily manipulated in the laboratory. If present, plasmids are always essential to cell survival. Plasmids are nonchromosomal DNA segments found in bacteria and a number of eukaryotic cells. Plasmids are commonly shared among cells by horizontal gene transfer mechanisms.

If present, plasmids are always essential to cell survival.

Which of the following is an example of phage conversion?

Infection of Streptococcus pyogenes with T12 phage enables the bacteria to produce erythrogenic toxins, allowing it to cause scarlet fever.

Which of the following terms is correctly matched with its description? Insertion mutations: Occur when a cell adds one or more nucleotides to its genome sequence. Substitution mutations: Occur when an incorrect fatty acid is added. Substitution mutations: Occur when an incorrect amino acid is added. Point mutations: Occur when an incorrect carbohydrate is added. Deletion mutations: Occur when one or more amino acids are removed from a protein sequence.

Insertion mutations: Occur when a cell adds one or more nucleotides to its genome sequence.

Choose the false statement about the eukaryotic cytoskeleton. View Available Hint(s) It assists with maintaining the cell's shape. It is an extension of the glycocalyx. It arises from the centrosome. It protects against external mechanical stress forces.

It is an extension of the glycocalyx.

Which of the following statements about the lagging strand is false? It synthesizes many RNA primers. It uses only one molecule of DNA polymerase I. It builds in the opposite direction of the helix unwinding. It is a discontinuous process. It is where one would find Okazaki fragments.

It only uses one molecule of DNA polymerase I

Choose the true statement about post-translational modifications. View Available Hint(s) Post-translational modifications are added to a limited number of distinct proteins in eukaryotes. Post-translational modifications include phosphorylation, trimming, and addition of organic factors. Post-translational modification occurs at the ribosome. Post-translational modifications affect how quickly an mRNA molecule is degraded following translation.

Post-translational modifications include phosphorylation, trimming, and addition of organic factors.

features of the prokaryotic ribosome that support the endosymbiotic theory.

Prokaryotes have a ribosome with a 70S sedimentation rate.

What is true about viral evolution?

RNA viruses mutate faster than DNA viruses due to a lack of proofreading replicative enzymes.

Which of the following is true about retrotransposons? Retrotransposons never remain in their original location. Retrotransposons can use a "copy-and-paste" strategy. Retrotransposons can use a "cut-and-paste" strategy. Retrotransposons rely on an RNA intermediate to insert into a new part of the genome. Retrotransposons do not require an RNA intermediate.

Retrotransposons rely on an RNA intermediate to insert into a new part of the genome.

Which of the following statements about reverse transcription is false? Reverse transcription uses RNA as a template. Reverse transcription builds copy DNA (cDNA). Reverse transcription uses special enzymes called reverse transcriptase. Reverse transcription requires a particular initiation sequence. Reverse transcription is performed by certain viruses and human cells.

Reverse transcription requires a particular initiation sequence.

Which of the following is mismatched? View Available Hint(s) Mitochondria: site of ATP production in a cell Ribosomes: central to RNA production in a cell Nucleus: houses the cell's DNA Cytoskeleton: maintains the cell's shape

Ribosomes: central to RNA production in a cell

which type of vesicle/vacuole is incorrectly matched with its description? Vacuole: Contains water and substances such as nutrients, toxins, or waste products Peroxisome: Protects the cell from hydrogen peroxide and other toxic oxygen intermediates Transport vesicle: Moves substances to diverse cellular destinations within the cell Secretory vesicle: Replenishes the lipid bilayer and deliver proteins for incorporation into the membrane Lysosome: Contains hydrolytic enzymes that break down substances engulfed by the cell

Secretory vesicle: Replenishes the lipid bilayer and deliver proteins for incorporation into the membrane

Which of the following vesicles is incorrectly matched with its function? View Available Hint(s) Peroxisomes: contain enzymes that break down fats and amino acids and protect the cell from hydrogen peroxide Transport vesicles: move substances around the cell Secretory vesicles: ferry digestive enzymes to the endoplasmic reticulum Lysosomes: contain hydrolytic enzymes and act as garbage disposal tools for the cell

Secretory vesicles: ferry digestive enzymes to the endoplasmic reticulum

Choose the true statement about the Domain Bacteria. View Available Hint(s) The Domains Bacteria and Archaea are genetically identical. The Domain Bacteria is made up of prokaryotes and likely originated 3.8 billion years ago. Bacteria inhabit extreme environments and are not linked to human diseases. The Domain Eukarya is more closely related to the Domain Bacteria than to the Domain Archaea.

The Domain Bacteria is made up of prokaryotes and likely originated 3.8 billion years ago.

What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane?

The cell will lose its interior water, causing it to shrivel up and possibly die.

Choose the true statement about protein synthesis. In eukaryotes, polysomes can develop before transcription finishes, whereas prokaryotic mRNA must first undergo processing. Prokaryotic cells produce polycistronic mRNA as a product of transcription, which must then be spliced to remove introns prior to translation. The first amino acid in a eukaryotic protein sequence is methionine, whereas the first amino acid in a prokaryotic protein sequence is formyl methionine. In eukaryotes, translation occurs in the nucleus; in prokaryotes, translation occurs in the cytoplasm.

The first amino acid in a eukaryotic protein sequence is methionine, whereas the first amino acid in a prokaryotic protein sequence is formyl methionine.

Choose the true statement about the genetic code. View Available Hint(s) The genetic code varies widely among organisms, with each having a different set of codons for a corresponding amino acid. The genetic code encodes 64 amino acids, one for each of the 64 corresponding codons. A cell's mRNA code is read four nucleotides at a time to specify a single amino acid. The genetic code is redundant, with multiple codons specifying a single amino acid.

The genetic code is redundant, with multiple codons specifying a single amino acid. Submit

Which of the following is a key difference between lytic and lysogenic bacteriophage replication cycles?

The lytic replication cycle ends with host cell lysis and release of newly formed bacteriophage particles, whereas lysogenic replication leads to prophage formation.

Choose the false statement about the cell's nucleus. View Available Hint(s) Unless the cell is dividing, the DNA of the nucleus is loosely organized as chromatin. The nucleus is typically visible with a light microscope. The nucleus contains a region called the nucleolus, where DNA is copied. The nucleus has a membrane that gives rise to the endoplasmic reticulum.

The nucleus contains a region called the nucleolus, where DNA is copied.

One ml of a liquid suspension of bacteriophage is mixed with its host bacteria and plated. After incubation, the plate is completely clear. What is the probable explanation?

The phage concentration was so high that all the host bacterial cells were killed.

Which of the following statements about the primosome is false? The primosome includes helicase to unwind the DNA. The primosome is recruited to the origin of replication.The primosome is responsible for starting DNA replication. The primosome includes RNA polymerase to build the protein .The primosome includes primase to lay down RNA primers that will jump-start replication.

The primosome includes RNA polymerase to build the protein.

You observe that a novel virus penetrates the host cell through membrane fusion. Which of the following statements must also be true regarding this virus and its replicative cycle?

The virus releases from host cells by budding

Choose the true statement about pre-transcriptional regulation. View Available Hint(s) This form of regulation controls when and how often pre-mRNA is processed to mature RNA. This form of regulation controls when and how often DNA is replicated. This form of regulation controls when and how often protein is built from mRNA. This form of regulation controls when and how often RNA is produced from a DNA template.

This form of regulation controls when and how often RNA is produced from a DNA template.

How does transformation differ from conjugation?

Transformation takes up DNA from the environment.

A previously undescribed infection has been detected among inhabitants in an isolated village in a remote tropical rainforest. When serum from an infected individual is passed through a filter, the infection can be transmitted to laboratory animals. Nothing is observed when the serum is examined with a light microscope at the highest magnification. Biochemical tests show the presence of RNA and protein but no carbohydrates or lipids. This data is consistent with what type of infectious agent?

VIRUS The infectious agent, invisible when viewed through a light microscope, was given the name virus

Hyphae are

a collection of tubular structures that result from fungal growth

How does the cell wall of bacteria and archaea differ?

bacteria use peptidoglycan

Which of the following is not a mechanism for horizontal gene transfer? View Available Hint(s) Conjugation Binary fission Transduction Transformation

binary fission

Viruses which infect many different tissues types are said to have a(n)

broad tropism

Prokaryotic and eukaryotic ribosomes share which of the following features? composed of a large and a small subunit and composed of protein and rRNA contain a large and a small subunit composed of protein and rRNA function is making DNA composed of protein and rRNA, composed of a large and a small subunit, and function is making DNA

composed of a large and a small subunit and composed of protein and rRNA

the genetic code

contains sense and nonsense codons

Bacterial cells use DNA replication to:

copy their genetic material prior to binary fission.

A similarity between mitosis and meiosis is

copying DNA before the cell divides

Cell shape is determined by

cytoskeleton and cell wall components

During lytic replication of bacteriophage, which process uses factors from the host cell, rather than coded by the viral genome?

enzymes which transcribe and translate viral genes

Which type of cellular transport uses transport proteins and moves substances from an area of high concentration to an area of low concentration?

facilitated diffusion

The _______ resembles a series of flat sacs called cisternae. This organelle modifies, builds, sorts, and distributes products to the cell membrane to be secreted. View Available Hint(s) Rough endoplasmic reticulum Smooth endoplasmic reticulum Plasma membrane Golgi apparatus

golgi apparatus

_____________ bacteria lack an outer membrane, have a thick layer of peptidoglycan, contain teichoic acid, and lack mycolic acid.

gram-positive

The primary function of the nucleus is

housing of cells DNA

__________ are a collection of tubular structures, either septate or aseptate, which allow for growth in most fungi.

hyphae

To maintain a fluid plasma membrane in cold conditions, bacteria may modify their plasma membranes by

incorporating short, unsaturated fatty acids into their membrane phospholipids

Prions are

infectious proteins misfolded proteins which can cause normal versions to also misfold.

When a virus has an envelope, When a virus has an envelope,

it likely escapes its host cell by budding.

Protozoans are mainly grouped by their __________.

means of motility

Once equilibrium is reached,

molecules move, but there is no net movement in a particular direction.

Mitochondria do not participate in which function? production of ATP programmed cell death production of amino acids and vitamins motility regulation of cell division

motility

Why is it so difficult to kill acid-fast bacteria?

mycolic acid limits drug entry

Fungal infections are called

mycoses

Helicase whats

unwinds the DNA

Where are cilia found in the human body?

upper respiratory tract

Which of the following nitrogen bases is found only in RNA and NOT in DNA? uracil guanine thymine adenine cytosine

uracil

Which of the following prion diseases may be acquired by eating beef contaminated with a cattle prion?

variant CJD

Challenges in developing effective antiviral drugs with minimal side effects to the patient include

viruses use the cell's own machinery and metabolism for replication.