Microbio quiz 2

hospital or healthcare acquired infections

nosocomial infections

Destruction of ALL living cells, spores, and/or viruses

sterilization

• Removal of disease-causing microorganisms from inanimate surfaces.

• Does not necessarily result in sterilization.

disinfection

• Removal of disease-causing microorganisms from living tissues, such as skin or mucous membrane.

• Does not necessarily result in sterilization

Antisepsis

• Reducing microbe numbers to “safe” levels.

• Does not necessarily result in sterilization

sanitation

(microbials) Lethal effects.

• Bactericidal agents kill bacteria.

• Fungicides, virucides, algicides, etc

Cidal agents

(microbials)

• Slow or stop metabolism or reproduction, but are not necessarily lethal

• Bacteriostatic agents inhibit bacterial growth.

• Fungistatic, virustatic, algistatic, etc.

static agents

External factors that influence the speed at which lethal damage

accumulates

initial population size, type of cells in population, duration of exposure, organic load

The __ ____ is the time required to kill 90% of cells.

D-value

Standard autoclave precautions

121 c, 15 psi for 20 mins

is the amount of time canned food should be

heated under pressure to kill 1012 endospores or reduce the

population size by 12 logs.

12D method

is a heat treatment invented by Pasteur in 1864 to kill bacteria that causes spoilage in fermenting beer and wine, without affecting the texture, color, or taste.

Pasteurization

Refrigeration temperature

4–8 c (39–43 f)

Freezing temperature

-70 C, -94 F

Freeze drying

Lyophilization

Filtration through filter with a pore size of ___ ____ removes

bacteria and bacterial endospores, yeasts, mold spores, algae, and

protozoa, but not viruses.

0.2 micrometers

To remove viruses, filters with pore sizes of ___ ___ are

necessary.

20 nm

Irridation dosage measured in units of ___

Gy

One joule of energy absorbed per kilogram of matter

1 Gy = 1 J/kg

Damages DNA makes them unable to reproduce or function

irridation

usefulness of a chemical agent depends on

organic matter, microbe present, corrosiveness, stability, odor, surface tension

their thick, waxy cell walls, which are rich in lipids and mycolic acids, making them resistant to many antibiotics, disinfectants, and environmental stresses

mycobacteria

a figure greater than __ indicates the disinfectant is more potent

than phenol

1

The _____ _______ _____ was a method once used to compare

disinfectants.

phenol coefficient test

The ___ _____ _____ is a modern test that determines how well a

disinfectant kills microorganisms dried onto a surface.

use-dilution test

List microbes in order from most to least resistant

bacteria spores, mycobacteria, small/non-enveloped viruses, fungi, vegetative bacteria, enveloped viruses

A _____ ____ stains two different kinds of cells in a

distinguishable manner.

differential stain

The most famous differential stain is the

gram stain

____ ______ cells that retain the stain appear dark purple.

gram-positive

____ _______cells are colorless and are counterstained a different color (pink).

gram-negative

Gram stain order (Come In And Stain)

crystal violet, iodine, alcohol, safranin

chromosomes are made up of

DNA

An organic molecule consisting of a nitrogenous base, pentose sugar, and one or more phosphate groups.

nucleotide

______ genomes have long coding regions followed by long non-coding regions, while ______ genomes have short coding (exons) and non-coding (introns) regions.

bacterial, eukaryotic

small, circular, additional pieces of DNA that bacterial cells may contain

plasmids

DNA replication is __________ and ___________.

bidirectional, semiconservative

DNA replication stage: Involves unwinding of the helix, priming, and loading of the DNA polymerase enzyme complex

initiation

DNA replication stage: The sequential extension of DNA by adding deoxyribonucleoside triphosphates (dNTPs) with release of pyrophosphate, followed by proofreading

elongation

DNA replication stage: The DNA duplication is complete and replication stops.

termination

The majority of genes are transcribed to _________ ____ ______, which encodes one or more peptides (proteins) to be translated by a ribosome.

messenger rna (mRNA)

______ ______ is a bacterial transcription initiation protein

that associates with the core RNA polymerase.

• Its main job is to recognize specific promoter sequences and

guide RNA polymerase to the correct starting site for

transcription.

Sigma factor

Once transcription begins, the sigma factor usually

________, and the core RNA polymerase continues

elongating the RNA.

dissociates

All protein synthesis requires ______ of the mRNA message into a peptide by the ribosome.

translation

Genetic code has ____ codons.

64

_____ specifies methionine, and is the START site of translation.

AUG

_____, ______, or ______ specify no amino acids; STOP sites for translation.

UGA, UAA, UAG

______ molecules transport amino acids to mRNA transcripts for

assembly into protein.

tRNA

phases of protein synthesis

initiation, elongation, termination

_______ is a crucial structural and catalytic component of ribosomes, the cellular machinery responsible for protein synthesis. It helps align mRNA with the ribosome and catalyzes the formation of peptide bonds between amino acids, building the polypeptide chain.

rRNA

Some microbes change the DNA sequence to activate or disable a particular gene.

changing the DNA sequence

can be regulated by protein repressors, activators, and alternative sigma factors.

control of transcription

Control of initiation sequences that recognize specific

repressor proteins

translational control

Control of proteins that are already made; for example, activate,

deactivate, or degrade the protein

posttranslational control

lactose operon in E. coli: Repressor binds to operator and blocks transcription.

No lactose

lactose operon in E. coli: Lactose binds to repressor, repressor fails to bind to operator, transcription occurs.

with lactose

A common mechanism bacteria use to sense the outside of the cell and transmit that information inside relies on a series of ___ _______ ______.

two-component regulators

Agent that causes mutations

mutagen

Occur in the absence of a mutagen

spontaneous mutations

• the base sequence must change

• The cell must fail to repair the change before the next round of replication.

requirements for heritable mutation

single nucleotide is changed in DNA sequence

point mutation

changes codon and leads to expression of altered protein

missense mutation

replaces amino-acid coding codon with codon that specifices no amino acid and terminates translation

nonsense mutation

a base-pair substitution changes a codon, but the new codon specifies the same amino acid as the original codon.

silent mutations

Addition or subtraction of one or more nucleotides

insertion/deletion

fragment of DNA is flipped in orientation relative to DNA on either side

inversion

When insertion of 1+ base pairs shift reading frame

frameshift mutation: insertion

When deletion of 1+ base pairs shift reading frame

frameshift mutation: deletion

UV radiation causes ________ _______. This causes a “bump” in the helix that fails to be read properly by the DNA polymerase leading to a gap or insertion of incorrect bases. May cause melanoma

pyrimidine dimers

UV radiation causes _______ ______, which light-repair can seperate.

thymine dimers

Damaged base is removed

base excision repair

In bacteria, the parental DNA strand is methylated. The newly synthesized strand is unmethylated for a short time. The repair machinery uses this difference to identify the new

(wrong) strand.

methyl mismatch repair

If DNA damage is extensive, cell takes drastic measure of introducing mutations into severely damaged DNA

SOS repair

recognize specific base sequences (restriction enzyme sites) and “cut” DNA

restriction endonucleases

__________ _____ is a DNA molecule containing sequences

from different source organisms.

recombinant DNA

Recombinant DNA generally requires a _______ molecule (plasmid DNA, viral genomes) to carry the DNA sequence of interest.

vector

Makes more copies of a portion of DNA

PCR (polymerase chain reaction)

PCR step 1: seperates DNA strands

denaturation

PCR step 2: strands are cooled and joined by primers

Annealing

PCR step 3: make more copies of DNA

DNA synthesis

technique to read sequence of base pairs in DNA molecule

DNA sequencing

extra turns in DNA beyond those generated by shape of base pairs

supercoils

unit of information encoded by DNA that can be copied to form RNA produce

gene

information determining when gene is expressed

promoter

Genes with shared ancestry and related function

homologs

proteins that affect the expression of many different genes

global regulators

virus has no envelope, but has capsid “shield”

naked virus

virus has capsid and envelope viral genomes

enveloped virus

(virus) DNA/RNA, some circular but most linear

viral genomes

Viruses are _______, infecting every taxonomic group of

organisms including bacteria, eukaryotes, and archaea

ubiquitous

Bacteriophages are used routinely as ______ ______, small

genomes into which foreign genes can be inserted and cloned for

gene technology.

cloning vectors

viruses that infect bacteria

bacteriophages

The entire infectious agent and life cycle

virus

the packaged, extracellular particle form of the virus.

virion

Each species of virus infects a particular group of host species,

known as the _____ ______.

host range

Viral genomes mutate faster/slower than bacteria.

faster

The __________ ______ classification of viral groups is based on whether the genome is composed of RNA or DNA; whether it is single- or double-stranded; and, if single-stranded, whether the strand directly encodes proteins or requires synthesis of a complement that encodes proteins

baltimore model

(virus) coding stand, directly used as mRNA

positive sense

(virus) template strand, + is generated from -

negative sense

Group I

Baltimore model: Double-stranded DNA

DsDNA, mRNA

Group 2

Baltimore model: Single-stranded DNA

ssDNA, dsDNA, mRNA