CH 7 Flashcards
entropy
disorder, randomness
energy
ability to do work
allows cells to perform functions
how does entropy change in a system?
decrease in entropy locally due to releases of heat + waste
this increases entropy of the system
primary producers
organisms that produce biomass from iorganic carbon
consumers
get nutrients from producers
what are some examples of primary producers?
photosynthetic microbes, plants
what are some examples of consumers?
heterotrophs, decomposers, humans
phototrophy
capure energy from light, light energy makes high-energy molecule that donates e- to acceptor
chemotrophy
high energy food molecule donates e- to acceptor
organotrophy, aerobic
organic molecule donates e- to O2
organotrophy, anaerobic
organic molecule donates to itself or other molecule, not O2
is organotrophy and lithotrophy a type of chemotrophy?
YES!
lithotrophy, aerobic
inorganic molecule donates e- to O2
lithotrophy, anaerobic
inorganic molecule donates e- to other molecule, not O2
metabolism
total of ALL chemical reactions in the cell. done in a series of steps to provide small amount of energy that are carried away by energy carriers
catabolism
breaking reactions, releases energy. source of e-
anabolism
building reactions, energy consumed. needs e-
metabolite
product or substrate of metabolism
enzymes
biological catalysts, control whether reactions occur and speeds up reactions by reducing activation E
activation energy
energy needed for reactants to reach the transition state between reactants and products
ΔG = ΔH - TΔS
Gibbs free energy equation, predicts direction of a reaction
-ΔG
reaction is spon., goes from high energy to low energy, releases energy
+ΔG
reaction isn’t spon., goes from low energy to high energy, consumes energy
is a catabolic reaction have a negative or positive Gibbs free energy?
negative, because catabolic reactions RELEASE energy, and a negative Gibbs goes from a high E state to low E state
what factors affect enzyme activity?
temperature, pH, salt concentrations, cofactors and coenzymes
does a higher temperature help enzymes proceed?
not necessarily, high temperatures denature enzymes. low temperatures slow enzymes as well
feed-back regulation
end-product of a metabolic pathway inhibits the activity of an enzyme used in that pathway
what are the benefits of using multi step pathways?
- store energy
- produce intermediates that can be used elsewhere
ATP is
common “energy currency”, molecule of RNA
what is ATP made up of?
one adenine base, one RNA sugar, and three phosphate groups
how do the phosphate groups facilitate the ATP’s function?
phosphate bonds are high in energy and store or release E
Substrate-level phosphorylation
intermediate in catabolism directly provides energy (and phosphate) to ADP
Oxidative phosphorylation
oxidation of nutrients creates PMF which drives ATP synthase
…. come back to this
ATP synthase
enzyme that converts ADP + P -> ATP
Photophosphorylation
Light energy creates a PMF that drives ATP synthase
light energy excites e-, pumps H+ outside cell
as H+ flow high-low, power ATP synthase
REDOX reactions
reactions that involve the flow of electrons
oxidation
substrate donates e-
reduction
subtrate accepts e-
e- carriers
help the cell transfer/harvest e- E. e- affinity needs to be higher at each step
what are some common microbial food sources?
cellulose and starch
pectin and sugar-acids
lipids
proteins
lipids and proteins
catabolized to products that enter the central pathways of glycolysis and TCA cycle
central carbon catabolism
carbon sources are chemically broken down
oxidative reactions
E is released and transferred to E carriers
(ATP, e- carriers)
what can intermediates of central carbon catabolism be used for?
biosynthesis pathways
how is central catabolism completed?
either by respiration or fermentation
glycolysis (AKA EMP pathway)
the oxidation of gluocse to pyruvate
input of glycolysis
1 glucose, 2 ATP
glucose breaks down into 2 pyruvic acids
ATP phosphorylate the sugar
output of glycolysis
4 ATP (NET 2 ATP)
2 NADH
2 pyruvate
substrates for biosynthesis (intermediates)
investment phase of glycolysis
6-C glucose requires energy to become 2 G3P
E required for controlled breakdown
pay-off phase for glycolysis
releases energy as 2 G3P is broken down into 2 pyruvate
alternative sugar catabolism
diff environments/species of bacteria catabolize sugars differently
can be sources of NADH, ATP, NADHP
overlap with glycolysis (G3P is common intermediate)
can occur in absence of O2
Entner-Doudoroff (ED) pathway
yields
1 NADPH
1 NADH
1 ATP
2 pyruvic acid
needed to metabolize certain sugar sources
Pentose Phosphate (PP) pathway
yeild can vary:
~2 NADPH
1 ATP
how must metabolism be completed?
e- and waste carbon from pyruvate need to be released from the cell via fermentation or respiration
cellular (aerobic) respiration
donates e- from NADH to ETS (electron transfer system), stores E by pumping H+ across the membrane
pyruvate oxidation (preparatory step)
input: 1 pyruvate (2 per glucose)
output: 2 CO2, 2 NADH, 2 Acetyl-CoA
TCA Cycle
transfers all e- to NADH & FADH2, releases stored energy through the oxidation of Acetyl-CoA into ATP
input/output of TCA
input: 2 Acetyl-CoA
output: 6 NADH
2 FADH2
2 ATP
4 CO2 (waste/carbon loss)
can a bacterial cell obtain a TCA intermediates from the environment and use them to make energy?
Yes if the cell has transporters to take up such molecules from the environment
Does the TCA cycle produce any useful intermediates ?
Yes, the TCA cycle produces substrates for biosynthesis such as amino acids, lipids, pigments, cofactors, etc
Electron transport chains (systems)
series of oxioreductase enzymes
oxidoreductase enzymes
- are membrane bound protein complexes
- pass e- from a stronger e- donor to a stronger e- acceptor
- release E which allows some complexes to move/pump H+ across the membrane
-generate a gradient (PMF)
chemiosmosis
protons moving down their concentration gradient
H+ gradient (charge + concentration gradient)
drives production of ATP and powers active transport
Is ATP snythase part of the ETC?
No, ATP only needs protons to work
ATP Snythase for bacteria occurs where?
embedded in the cell membrane
ETC starts and ends how?
ETC starts when e- carriers pass off e- to ETC. it ends when e- are passed to the final e- acceptor
does NADH or FADH2 produce more ATP?
NADH produces ~3 ATP while FADH2 produces ~2 ATP
what is the theoretical ATP yield from 1 glucose in aerobic conditions?
38.
from glycolysis, 2 NADH = 6 ATP
from pyruvate oxidation, 2 NADH = 6 ATP
from the TCA cycle, 6 NADH = 18 ATP, 2 FADH2 = 4 ATP
why is theoretical maxium never reached in bacteria?
Bacteria use PMF forces used for ATP production for other cellular processes + to maintain stable ion gradients during extreme changes
where does TCA reactions and ETC occur in eukaryotic cells?
Mitochondria. TCA occurs in the matrix and ETC is located in the inner membrane
where does TCA reactions and ETC occur in prok cells?
cytoplasm and cell membrane
where does glycolysis, oxidoreductases, and ATP synthase occur in cells?
the locations are highly similar for both proks and euks. gylcolysis occurs in the cytoplasm for both
What is different about ETC and PMF in prok?
No mitochondria - occurs across the cell membrane
number/arrangement of complexes
cytochrome C placement
final complex
what is the same?
general redox centers
the goal - step-wise transfer of E from e- to proton gradient to ATP
a membrane is needed
ATP synthase is the enzyme used for the final step of oxidative phosphorylation
fermentation also completes catabolism!! how?
partially!
how does fermentation to complete catabolism work?
e- E transferred to pyruvic acid.
glycolysis + fermentation occurs:
ATP is made, no O2 is needed, and pyruvic acid is the final e- acceptor
two main types of fermentation
lactic acid and alcohol
alcohol fermentation steps
- pyruvic acid is converted to acetaldehyde, CO2 is released
- acetaldehyde is reduced to ethanol
what is detecting fermentation end products useful for?
indentifying microbes
