micro test 2

sources of essential nutrients

heterotroph- obtain carbon in organic form from other living organisms

• saprobes- eat dead organisms

• parasites- derive nutrients from the host

autotroph- uses CO2 as carbon source

chemotroph- gain energy from chemical compounds

phototrophs- gane energy through photosynthesis

temperature adaptations

psychrophiles- below 15C capable of growth at 0C

• psychrotroph- capable of growth below 7C but optimum above 20C

mesophiles- optimum 20C-40C (most human pathogens)

thermophiles- optimum temp greater than 45C

• hyperthermophile- optimum temp above 80C

categories of oxygen requirement

obligate aerobe- needs oxygen

facultative anaerobe- utilizes oxygen but can grow in its absence

microaerophilic- requries small amount of oxygen

obligate anaerobe- cannot survive in envt with oxygen

aerotolerant anaerboes- do not utilize oxygen but can survive and grow in its presence

halophiles require high salt concentration

barophiles can survive under extreme pressure and will rupture if exposed to normal atmospheric pressure

ecological associations

obligate mutualism- both benefit, dependent

nonobligate mutualism- both benefit but can live independently

commensalism- commensal member benefits, other neither harmed nor benefited

parasitism- parasite is dependent and benefits, host is harmed

population growth

Nf = initial cell number x 2^n

where n is number of generations

population growth curve: lag phase, exponential growth, stationary phase, death phase

enzyme structure

holoenzymes- contain protein and nonprotein enzymes (conjugated)

apoenzyme- protein portion

cofactors- nonprotein portion

• metallic (iron, copper, mg), coenzymes (vitamins, organic molecules)

lock and key- enzyme fits perfectly to substrate

induced fit- substrate changes shape to perfectly fit enzyme

constitutive enzymes- always present, always made in equal amounts regardless of amount of substrate

regulated enzymes- not constantly present (induced or repressed in response to changes in substrate concentration)

ATP formation mechanisms

substrate level phosphorylation- transfer of phosphate group from substrate to ADP

oxidative phosphorylation- redox rxns occurring during respiratory path

photophosphorylation- ATP formed utilizing energy of sun

metabolic strategies

aerobic

• glycolysis: glucose split into 2 molecules of pyruvic acid, 2 ATP, and 2 NADH

• TCA: processes pyruvic acid and generates 3Co2, Nadh and fadh2

• ETC: accepts e- from nadh and fadh, generates energy from sequence of redox rxns called ox phosphorylation

anaerobic

• utilizes oxygen containing ions instead of free oxygen as final e- acceptor (nitrate and nitrite)

fermentation

• incomplete oxidation of carbs in absence of oxygen that uses organic compounds as e- acceptors and yield small amount of ATP, acid, gas

photosynthesis

• light dependent stage- photons absorbed by pigments, water split, o2 released (ATP and NADPH made)

• dark rxns- uses ATP to fix CO2 to ribulose-1,5-bisphosphate to convert it to glucose

schistosomiasis (parasitic disease) life cycle

adult flukes like in humans who release eggs into water → early larva develops in freshwater snail to 2nd larva which penetrates human skin and matures in liver → migrate to intestine/bladder to shed eggs → chronic organ enlargement

DNA replication (semiconservative)

at origin of replication helicase unwinds DNA and RNA primer is synthesized by primase

DNA pol 3 addes nucleotides 5’→3’ (leading strand is continuous, lagging strand is in short segments)

DNA pol1 removes RNA primers and replaces with DNA

transcription and translation

TRANSCRIPTION

initiation: promoter binding

propagation: RNA pol adds nucleotides 5’→3’

termination: release of RNA transcript

TRANSLATION

initiation, elongation, termination, protein folding, post-translational processing

operons and regulation

operon: set of genes regulated as a single unit

inducible: operon is turned on by substrate; catabolic means enzymes needed to metabolize a nutrient are produced when needed

repressible: genes in a series are turned off by product synthesized; anabolic means enzymes used to synthesize aa stop being produced when they are not needed

regulator: gene that codes for repressor

control locus: promoter and operator

structural locus: made of 3 genes each coding for an enzyme needed to catabolize lactose

mutations

missense- 1 aa change

nonsense- causes stop codon

silent: alters a base but not aa

back- mutated gene reverses to original base composition

frameshift- reading frame of mRNA is altered

recombination in bacteria

CONJUGATION

• transfer of plasmid from donor cell to recipient via direct connection (G- donor has F plasmid that allows synthesis of conjugative pilus)

• high freq recombination- donor’s F plasmid has been integrated into bacterial chromosome

TRANSFORMATION

• chromosome fragments from lysed cell are accepted by recipient (Griffith experiment)

TRANSDUCTION

• bacteriophage serves as DNA carrier from donor to recipient

• generalized- random fragments of disintegrating host DNA picked up by phage during assembly

• specialized- highly specific part of host genome is regularly incorporated into the virus

vibrio cholera

comma shaped bacteria ingested from food/water (alkaline conditions)

releases cholera toxin → electrolyte and water loss through rice water stool → muscle, heart, neuro symptoms

treatment: oral rehydration