Micro Quiz Chapters 7 and 13

Ionizing radiation

(x-rays, gamma rays) ionizes water to release OH, damages DNA (can break DNA) used to sterilize medical supplies and food products

cancer

activated oncogenes transform normal cells into cancerous cells

Antibiotics

Nisin (bacteriocin) and nitamycin prevent spoilage of cheese

DNA makes RNA

RNA makes proteins

hepa filters are used to remove microbes from?

air

iodine

alter protein synthesis and membranes tinctures: in aqueous alcohol iodophors: in organic molecules, iodine and organic molecules (common used in betadine)

disk diffusion tests

antibotic efficiency

which of the following is not used as a antiseptic?

aqueous glutaraidehyde

viruses that infect bacteria are called?

bacteriophages

viruses must be grown in living cells

bacteriophages form plaques on a lawn of bacteria animal viruses may be grown in living animals or in embryonated eggs or in cell cultures

which agent inhibits the growth of bacteria?

bacteriostatic agent

why are the pseudomonads less affected by the four chemicals shown?

because of gram negative outer membranes that are resistant to antibiotics

what is the general size of most viruses?

bigger than a protein

what is the general size of virsuses?

bigger than a protein, most bacteria bigger than viruses

release

by budding (enveloped viruses) or rupture (non enveloped viruses)

release AV

by budding (enveloped viruses) or rupture (non enveloped viruses)

morphology

by different structures in coat helical viruses polyhedral viruses enveloped viruses complex viruses

penetration AV

by receptor mediated endocytosis or fusion

uncoating AV

by viral or host enzymes

which of the following best describes the pattern of microbial death?

the cells in a population die at a constant rate

what can be a problem if a viral vaccine is produced using embryonated eggs?

can cause allergic reactions in people who are allergic to eggs

capsid

capsomeres, enveloped or non enveloped, spikes

papilloma viruses

cause uterine (cervical) cancer, virtually all cervical and anal cancers are caused by human papillomavirus (HPV), a vaccine is available

chlorine

chlorine gas: water, sewage, waste water, inanimate objects -blech, hypochlorous acid (HOCI) -chloramine: chlorine + ammonia (used to clarify water) -oxidizing agents

what is host-cell deterioration due to animal viral infections termed?

cytopathic effect

the skin is swabbed with alcohol before antibiotic injection, this process is called?

degermation

microbial contamination of milk should be measured quickly, so which method below is most appropriate for that?

direct colony counting using the cell counter

persistent

disease process occurs over a long period, generally is fatal, ex. measles

If you remove microorganisms from your computer mouse using 5% bleach, this is?

disinfection

phenol and phenolics

disrupt plasma membranes, phenol is the gold standard of disinfectants and other disinfects are often compared to it to rate their effectivness, phenol and o-phenylphenol (cresols)

chlorhexidine (a biguanide)

disrupts plasma membranes, used as skin degerming agents for preoperative scrubs, skin cleaning, and burns, is not absorbed into the skin

microwaves

do not have much direct effect on microorganisms and bacteria can readily be isolated from the interior of recently operated microwaves

which nucleic acid do viruses use as a genetic material?

either DNA or RNA, never both

alcohols

ethanol, isopropanol denature proteins, dissolve lipids (destroys protein shapes and membranes) 70% ethanol is more effective than 100% (better protein coagulant) hand sanitizers contain alcohols, kills microbes very well, pure alcohol doesn't kill microbes well

Gaseous sterilants

ethylene oxide -alkylation then crosslinking of nucleic acids and proteins -denature proteins -sporicidal use: heat sensitive material and prepackaged devices (ex. disposable lab plastics) toxic and highly explosive

ionizing radiation (gamma rays and xrays) cannot be used to sterilize medical supplies and food products because they are too dangerous?

false

Viral Multiplication

for a virus to multiply, it must invade a host cell and take over the hosts metabolic machinery, usually causes host cells death, in a few viral infections cells survive and continue to produce viruses

Are quats most effective against gram positive or gram negative bacteria?

gram positive

Why are cancerous cells (transformed cells, continuous cell lines) used for cell cultures?

grow more cells because they grow continuous, used to grow viruses, ex. hela cells

bisphenols

hexachlorophene, triclosan (found in hand soaps) disrupt plasma membranes hexachlorophene-found in prescription lotion triclosan-in antibacterial soap

Radiation

high energy radiations can kill microorganisms -ionizing radiation -non ionizing radiation shorter wavelength = more energy

transformed calls have

increased growth, loss of contact inhibition, chromosomal abnormalities, tumor specific transplant antigens and t antigens, the genetic material of oncogenic viruses becomes integrated into the host cells DNA

halogens

iodine, and chlorine

host range

is determined by specific host attachment sites and cellular factors

how do latent and persistent infections differ?

latent shows up later than persistent and is not fatal

non-ionizing radiation

little penetrating power, so it must be directly exposed 1. UV light creates thymine dimers, which interfere with replication and transcription 2. Disinfection or sterilization *cant kill all but most pathogens/microbes

hepatitis B virus HBV

liver cancer, vaccine available

what is the chemical composition of a capsid?

made up of proteins called capsomeres

to sterilize heat-labile (sensitive) solutions, which one below is the safest method?

membrane filtration

121C for at least 15 mins is the condition of

moist heat, autoclave

maturation AV

nucleic acid and capsid proteins assemble

maturation

nucleic acid and capsid proteins assemble usually a spontaneous process

general characteristics viruses

obligatory intracellular parasites acellular no plasma membrane no ribosomes no ATP generating mechanism (borrow hosts energy) not sensitive to antibiotics (kills bacteria) contain DNA or RNA (never both) contain a protein coat some viruses are enclosed by an envelope some viruses have spikes

chemical food preservatives

organic acids -sorbic acid, benzoic acid and calcium propionate -inhibit metabolism (of microorganisms) -control molds and bacteria in foods and cosmetics -safe

the definition of lysogeny is?

phage DNA is incorporated into host cell DNA

lytic cycle

phage causes lysis and death of host cell

chemical methods of microbial control

phenol an phenolics bisphenols chlorhexidine halogens alcohols quats aldehydes

what is a plaque forming unit (PFU)?

plaque can be made by one bacteriophage-number of clearings, each one corresonds to a single virus in the inital suspension, when more grow together its a PFU

Nitrite (nitrits)

prevents botulism endospore germination but produces the carcinogen nitrosamines (causes cancers)

biosynthesis AV

production of nucleic acid and proteins

what is the bacteriophage genome incorporated into the host chromosome called?

prophage

lysogenic cycle

prophage DNA incorporated in host DNA, phage conversion

oncogenic RNA viruses

retroviruses-provirus reverse transcriptase, viral RNA is transcribed to DNA which can integrate into host DNA, human T cell leukemia virus, HTLV-1 HTLV 2

do all viruses have the same shape?

shapes are different/ how classified

Surface-Active Agents, or Surfactants

soap-mechanical removal of microbes through scrubbing acid anionic detergents (- charge) sanitizing Quats (quatemary ammonium compounds) cationic detergents, batericidal, denature proteins, disrupt plasma membrane

which machine is used to measure the turbidity of bacterial cultures?

spectrophotometer

Aldehydes

sterilants, + can kill microbes and endospores, in between alcohol and acids Formaldehyde (gas) formalin (37% solution) and glutcraldehyde (cidex, 2% solution) -kills microbes can preserve long time inactive proteins by cross linking with functional groups (-NH2, -OH (alcohol) -COOH (acid) -SH) use: medical equipment, embalming by morticians

A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient?

the virus is causing the death of the infected cells in the patient

why is UV not used to sterilize foods?

their power is too weak to penetrate foods

which of the following statements about spikes is true?

they are found mostly on enveloped viruses

which of the following statements about viral spikes is false

they are used for biosynthesis of DNA and proteins, they are used to bind receptors on the host, found on enveloped viruses, composed of carb protein complexes or viral glycoproteins

which chemical cannot be used to preserve foods?

triclosan

a viral envelope is acquired during the release step

true

Of what is a viral envelope composed of?

viral proteins and the host cells membrane which contains phospholipids

viral structure

virion, viruses are classified by -their nucleic acid -differences in the structures of their coats Nucleic acid DNA or RNA (never both) single or double stranded DNA or RNA linear or circular DNA or RNA

latent

virus remains in asymptomatic host cell for long periods, ex. cold sores by simplexvirus, shingles by zoster virus

t antigens

virus specific antigen in nucleus

tumor specific transplant antigens TSTA

virus specific antigen on cell surface

attachment AV

viruses attach to cell membrane, by binding between viral capsid protein or spikes and host proteins or glycoproteins on the plasma protein

Which is not the major target of microbial control agent?

water