N4110 Microbiology Week 2_Else

Polyhedral capsids

Capsid is a polyhedral icosahedron (20-sided structure with 12 vertices) surrounding a nucleic acid Poliovirus, rhinovirus

Helical capsid

Capsid is cylindrical or rod-shaped with genome fitting just inside the length of the capsid Tobacco mosaic virus, Ebola virus

Steps of the lytic cycle

Attachment, entry/penetration, biosynthesis of new viral components, maturation, lysis

Steps of the lysogenic cycle

Attachment, penetration, phage DNA incorporated, replication, phase DNA excised and enters the lytic cycle at biosynthesis of new viral components and ending in lysis

Which of the following species of bacteria is known to live in the stomachs and duodenums of many people and is a leading cause of ulcers, gastritis, and stomach cancer? Helicobacter pylori, Salmonella typhi, Vibrio cholerae, Haemophilus influenzae

Helicobacter pylori

Neutralism

Neither organism is affected

Oxidase Positive

Bacteria which use oxygen as the final electron acceptor in aerobic respiration

Pathogen

A disease-causing agent that disrupts the normal physiology of the infected organism

Fermentation

A metabolic process that produces chemical changes in organic substrates through the action of enzymes

Parasite

A microorganism that depends on another living organism host for its life cycle; it may or may not cause any disease or affect the health of the host

Motile

Ability of bacteria to move independently using metabolic energy

Oligotroph

An organism that can survive in a nutrient-poor environment

Eutroph/copiotroph

An organism that requires a copious amount of organic nutrients

Mechanical vector

Arthropod carries a viral pathogen on the outside of its body, transmits via physical contact

Biological vector

Arthropod carries viral pathogen within its body and transmits it to a new host via bites

Among the bacterial species that live in the human GI tract, which one of the following bacteria groups comprises 30% of the population? Bacteriodes, Spirochetes, Fusobacterium, Cytophaga

Bacteriodes

Viruses that infect bacteria are referred to as... Bacteriophages, retro viruses, bacteriophillic viruses, enveloped virsus

Bacteriophages

Complex viral shape

Bacteriophages with features of polyhedral and helical viruses Genome located within polyhedral head, sheath connects head to tail fibers Poxviruses (brick shaped, complex surfaces)

Mutualism

Both organisms benefit (e.g., E. coli in human GI tract)

Viruses contain genetic material in the form of DNA and RNA but not both, both DNA and RNA, ATP and polymerase enzymes, none

DNA or RNA but not both

Fastidious

Difficult to culture, complicated nutritional requirements

How are Chlamydia species classified? Gram-negative obligate intracellular pathogens, Gram-negative pneumotrophes, Gram-negative non-proteobacteria, Gram-positive obligate intracellular pathogens

Gram-negative obligate intracellular pathogens

Retroviral life cycle

HIV fuses to host cell surface HIV RNA, reverse transcriptase, integrase, and other viral proteins enter the host cell Viral DNA is formed by reverse transcription Viral DNA is transported across the nucleus and integrates into the host DNA New viral DNA is used as genomic RNA and to make viral proteins New viral RNA and proteins move to the cell surface and a new, immature HIV forms The virus matures when protease release the proteins that form the mature HIV

Qualities of viruses

Infectious, acellular pathogens Obligate intracellular parasites with host and cell-type specificity DNA or RNA genome (never both) Genome is surrounded by a protein capsid and sometimes a phospholipid membrane studded with viral glycoproteins Lack genes for many products needed for successful reproduction, requiring exploitation of host-cell genomes to reproduce

The bacteria Staphylococcos aureus is an organism that causes frequent pathogenic infections in humans and belongs to which group of bacteria? Low G+C Gram positive Bacilli, Low C+B Gram positive Lactobacillales, High G+C Gram negative Bacilli, High G+C Gram negative Cocci

Low G+C Gram positive Bacilli

Highly virulent viruses go through a life cycle termed: Lytic Cycle Lysogenic Cycle

Lytic Cycle

Which one of the following terms best describes the relationship between humans and the strain of E. coli that lives in the human GI tract, consumes nutrients from the foods we eat, and synthesizes vitamin K? Mutualism, comensalism, parasitism, neutralism

Mutualism

Facultative

Occurs optionally in response to various circumstances or environment

Parasitism

One organism benefits, the other is harmed

Commensalism

One organism benefits, the other is unaffected

Ammensalism

One organism is unaffected, but harms the other

Malaria is caused by Plasmodium, Paramecium, Staphylococcus auereus, Vibrio cholera

Plasmodium

Nitrogen fixation

Prokaryotic process of converting atmospheric nitrogen into ammonia

Carbon fixation

Prokaryotic process of converting carbon dioxide to organic carbon products; animals need prokaryotes to do this

Obligate intracellular pathogen

Relies upon host cell intracellular resources for its reproductive cycle (cannot reproduce outside of host cell)

Anaerobic

Requires an absence of free oxygen

Aerobic

Requires free oxygen

Microaerophilic

Requries low levels of free oxygen

Obligate

Restricted to a particular function or mode of life

Pleiomorphic

The ability of a microorganism to change shape under varying conditions

Zoonose

Virus that can be transmitted from an animal to a human host

Bacteriophage

Virus that infects bacteria

Viruses as infection-causing

Viruses are obligate intracellular parasites because they are not alive (because they are acellular) Virions - new virus particles formed in the host cell

Naked/nonenveloped viruses

Viruses formed from only a nucleic acid and capsid

Enveloped viruses

Viruses formed with a nucleic acid-paced capsid surrounded by a lipid layer

A virus that lives out a lysogenic cycle... incorporates its genes with the host cell's DNA and is replicated when the cell replicates, shuts down replication of the host cell's DNA, Causes the host cell to quickly die and shed new virus, Is a far more virulent virus

incorporates its genes with the host cell's DNA and is replicated when the cell replicates