microbiology exam 2

biol 250

haemophilus influenzae (HiB)

invasive, can be transmitted by direct contact or airborne

pure culture

single species

solid media

firm surface to form multiple colonies

isolation streaking (streak method)

ability to get a pure culture

spread plate technique

isolating pure colonies by diluting original culture on agar plates

minimal medium

least amount of nutrients needed for an organism to grow

complex medium

more nutrient-rich, less defined, in labs

enriched medium

used to grow fastidious organisms

selective media

only want one bacteria

differential media

2 different organisms

E. coli

number 1 cause of UTIs, gram negative bacillus

binary fission

bacteria reproduce, 1 cell becomes 2

exponential growth

population size doubles at a fixed rate

generation (doubling) time

bacteria will divide at a constant interval

phases of growth for bacteria

lag, log, stationary, death

lag phase

preparation

log phase

multiplying

stationary phase

no growth

essential nutrients

compounds a microbe must gather from environment in order to grow and divide

autotrophs

makes CO2

heterotrophs

obtains CO2

phototrophs

use light as an energy source (photosynthesis)

chemotrophs

use potential energy in chemical compounds as energy source

nitrogen

obtained from protein (animals), needed top make proteins and nucleic acids

"normal" physiologic conditions of microbes

68-104F and near neutral pH

extremophiles

bacteria, archaea, and some eukaryotic microbes that can grow in extreme environments

thermophiles

like hot temps (158F)

hyperthermophiles

like extremely hot temps (up to 250F)

psychrophiles

like cold temps as low as 14F

mesophiles

middle/regular common microorganism

barophiles

likes pressure (high)

halophiles

loves salt

neutraphiles

bacteria grow between pH 5-8

acidophiles

like acidic environments

alkaliphiles

like alkaline environments

strict aerobes

needs oxygen

strict anaerobes

can't have oxygen

microaerophiles

live in low oxygen

aerotolerant

doesn't want O2 but can TOLERATE it

facultative anaerobes

can like with or without oxygen

biofilm

mass of bacteria that sticks to surface (ex. teeth)

cystic fibrosis (CF)

thick sticky mucus buildup in lungs due to chloride transportation

endospores

gram-positive bacteria, heat-resistant, resist drying, freezing and chemical disinfectants

examples of endospores

bacillus, clostridium

shigella

number 1 cause of bloody diarrhea, transmitted from drinking contaminated water

catabolism

energy-releasing reactions (releases), macromolecules are broken down

anabolism

energy-capturing reactions (absorbs), macromolecules are built

oxidation

substrate donates electrons (loses)

reduction

substrate accepts electrons

electron carriers

NAD, FAD, ATP

carbohydrate (sugar) catabolism

glycolysis splits sugar molecules and energy is transferred to ATP

glycolysis

the breakdown of glucose releasing energy and pyruvic acid.

fermentation

anaerobic, makes organic acids and alcohols (yeast)

TCA cycle (Krebs)

removes remaining electrons leaving CO2, electrons are transferred by NADH and FADH2, some ATP is made

Respiration

aerobic, makes a lot of ATP

bacterial genomes

organized differently than eukaryotic organisms (contained on single chromosome)

plasmids

smaller pieces of DNA that replicate separately from the genome

translation

mRNA is converted into amino acids in the ribosome

start codon

AUG

stop codons

UAA, UAG, UGA

tRNA

one end with anticodon of mRNA, other end contains amino acid

RNA polymerase

always required for growth

transcription

in nucleus, DNA converted to mRNA

induction

to make a protein

repression

to not make a protein

repressor proteins

stop gene expression (ex. iron for toxin)

no lactose

repressor blocks transcription

with lactose

lactose binds to repressor and transcription occurs

point mutation

changes a single nucleotide

two basic requirements for a heritable mutation

base sequence must change, cell fails to repair change

missense mutation

changes amino acid

nonsense mutation

creates stop codon

silent mutation

codon changes but same amino acid

pyrimidine dimers

DNA mutations that result from UV exposure

base excision repair

damaged base is removed

methyl mismatch repair

enzymes bind to strand and fix damage

SOS repair

coordinated cellular responses can introduce mutation to save the cell

recombinant DNA

DNA produced by combining DNA from different sources

vector molecule

generally required for recombinant DNA, include plasmids and viral genomes

horizontal gene transfer

transformation, conjugation, transduction

transformation

process of importing free DNA into bacterial cells

conjugation

cell to cell contact (sex) to transfer DNA

bacteriophages (phage)

viruses that infect bacteria

generalized transduction

phage capsid mistakenly fills with a fragment of bacterial DNA instead of phage DNA

specialized transduction

phage genome initially integrates into a specific DNA sequence in the host genome

endosymbiosis

mutualistic relationship between host and symbiont where each is required for normal growth and development

taxonomy

classifying bacteria by classification, phylogeny, nomenclature

classification

organizing life into groups

phylogeny

evolutionary history and relatedness of organisms

nomenclature

system of naming living things

gram positive bacteria

thick cell walls, produce endospores, staph and strep

gram negative bacteria

diverse phylum, includes bacteroidetes, e. coli and salmonella

spirochaetes

tightly coiled cells with flagella underneath a sheath

spirochaetes examples

borrelia burgdorferi

cyanobacteria

include tiny marine bacteria as well as massive filamentous species, only bacteria that produce oxygen

chlamydiae

intracellular pathogens that grow as inclusion bodies within host cell (parasite)

chlamydiae example

chlamydia trachomatis

bacteria with positive gram-positive cell walls

firmicutes, actinobacteria

firmicutes

tough skin, several layers of peptidoglycan supported with teichoic acids

actinobacteria

peptidoglycan with additional thick waxy coat, antibiotic producers, decomposers, pathogens