bacterial metabolism - notes and lecture Flashcards
how does bacterial metabolism compare with eukaryotic metabolism?
in general, the same - but we’re focusing on glucose metabolism
what occurs in glycolysis?
glucose is oxidized to pyruvate
how does glycolysis allow for energy generation?
transfer of electrons from the glucose allows for production of ATP via direct, substrate-level phosphorylation
other electrons transfered to NAD+ to make NADH
what is the molecular equation for the formation of NADH?
NAD+ + 2e- + H+ –> NADH
what is the energy requirement and production of glycolysis?
for every mole of glucose, 2 moles ATP consumed, 4 moles of ATP produced, and one equivalent of NADH if formed from NAD+
what is the tricarboxylic acid cycle?
liberates reducing equivalents that drive ATP formation via oxidative phosphorylation
what is the glyoxylate shunt?
similar to krebs cycle but lacks many krebs cycle enzymes
consumes acetyl CoA, which is generated from acetate
goes from icoselate to malate
what is the major product when microbes grow on FA?
acetate (this pathway generally absent in mammals)
describe the electron transport chain in bacteria.
NADH donates electrons
transfer of electrons through electron transport chain converts energy of electrons into a proton gradient
proton gradient used to make ATP
what is the terminal electron receptor in the electron transport chain?
in aerobic respiration = O2
O2 + 2e- => H2O
in some bacteria, can respire anaerobically - use terminal electron acceptor other than O2, such as NO3-
what is oxidative phosphorylation? where does it occur?
production of ATP by electron transport chain process
in mammalian cells happens in mitochondria
in bacteria occurs across cytoplasmic membrane
when does fermentation occur? what is the process?
when there’s a lack of O2 => ETC and TCA cycles “back up” => some of the pyruvic acid made from glucose during glycolysis is reduced using NADH => NAD+ regeneration and fermentation product
how does fermentation produce energy?
ATP made by transfer of high-energy phosphate to ADP
no respiratory chain involved
via substrate-level phos only
how do the different forms of energy production compare in terms of efficiency? what are the equations for these processes?
aerobic respiration yields more energy per mole of glucose than fermentation does aerobic respiration: glucose + 6O2 --> 6CO2 + 6 H2O -deltaF = 688,000 cal fermentation: glucose --> 2 lactic acid -deltaF = 58,000 cal
what is the most simple fermentation pattern?
lactic acid fermentation
direct reduction of pyruvic acid by NADH and lactic dehydrogenase enzyme
what is the role of NADH in respiration and fermentation?
in respiration: donates its electrons to teh ETC in cytoplasmic membrane => NAD+ and proton gradient => ATP generation
in fermentation: NADH donates electrons to carbon-based substrate to generate fermentation product that’s excreted - NAD+ generated, but no additional ATP made in this step
which types of phosphorylation make ATP in respiration and in fermentation?
in respiration, oxidative phos
in fermentation, substrate level pho
what happens to the carbon from the growth substrate in respiration and fermentation?
in respiration, either as CO2 or assimilated into cellular material - nearly completely oxidized
in fermentation - reduced fermentation products in order to regenerate NAD+
