ch 3- cellular energy Flashcards
where do chylomicrons go
leave enterocytes and enter leacteals (lymphatic vessels that take fats to the rest of the body)
how are fats released into circulation
adipocytes have hormone sensitive lipase enzymes that release triglycerides back into circulation as lipoproteins or free fatty acids bound by albumin (protein)
proteins as energy source
least desirable energy source (4
kcal/gram) because the processes to get them into cellular respiration take considerable energy and proteins are needed for many essential functions in the body.
fats as energy source
Fats are harder to catabolize than carbohydrates as they must undergo beta-oxidation and transport away from fat cells. However, per carbon molecule, fats are the most efficient source of energy containing about ~9 kcal/gram.
what happens when fats undergo beta oxidation
convert to acetyl co-A
where does beta oxidation occur
in the mitochondrial matrix of eukaryotic cells
- requires initial investment of ATP
-then FA chain cleaved into 2 carbon acetyl coA moleucules
what happens to the 2 carbon acetyl coa molecules made from beta oxidation
can be used in the krebs cycle for ATP generation and in the process, we make FADH2 and NADH
electron carriers in Electron transport chain (NADH and FADH2- produces more ATP
lipases
digest fats into Free fatty acids and alcohols during lypolysis
diested peices then are absorbed into enterocytes in small intestine to reform triglycerides
glycogenesis
conversion of glucose into glycogen to be stored in the liver and muscle cells when energy and fuel is sufficient.
preferred energy source
Carbohydrates are the preferred energy source since they are easily catabolized and are high yield (4 kcal/gram).
glycogenolysis
release of glucose-6-phosphate from glycogen,h
how do dissacharides enter glycolysis
Disaccharides can undergo hydrolysis to release two carbohydrate monomers, which can enter glycolysis.
obligate aerobes
only perform aerobic respiration
need oxygen to survive
obligate anaerobes
only undergo anaerobic respiration or fermentation
o2 is poisonous to them
facultative anaerobes
anaerobes: Can do aerobic respiration, anaerobic respiration, or fermentation
PREFER AEROBIC RESPIRATION BC IT GIVES THEM MORE ENERGY
found all throughout the tube but most conc in the top
microaerophiles
Only perform aerobic respiration, but high amounts of oxygen are harmful to them.
aerotolerant organisms
Only undergo anaerobic respiration or fermentation, but oxygen is not poisonous to them.
found interspersed throughout the tube
alcohol fermentation
uses
-2 NADH from glycolysis
to convert 2 pyruvate to 2 ethanol
producing NAD+ allowing glycolysis to continue
1 GLUCOSE uses 2NAD+ and 2 ADP to form 2 pyruvate (3 carbons each)
each pyruvate loses CO2 producing 2 acetaldehydes
each is reduced by NADH reforming NAD+ to produce 2 two carbon ETHANOLs
which type of fermentation has an extra step
alcohol fermentation
involves decarboxylation of pyruvate into acetaldehyde which is then reduced by NADH into ethanol
lactic acid fermentation
one glucose- 2 NAD+ and 2 ADP turns it into 2 pyruvate
2 NADH reduce the two pyruvates into two 2 carbon lactates
NAD+ reformed to go back to glycolysis
cori cycle
convert lactate back into glucose once oxygen is available again.
transports the lactate to liver cells, where it can be oxidized back into pyruvate. Pyruvate can then be used to form glucose
where does lactic acid fermentation occur
in muscles when Oxygen is low
and ALWAYS in red blood cells that lack mitochondria needed for aerobic respiration
where does fermentation occur
in the cytosol
what does fermentation rely on
glycolysis by converting the
produced pyruvate into different molecules in order to
oxidize NADH back to NAD+
Regenerating NAD+
means glycolysis can continue to make ATP.
what is ATP synthase
channel protein
allows protons to move DOWN electochemical gradient
where do protons more from in ATP synthase
FROM intermembrane space TO mitochondrial matrix
generates energy that is used to concert ADP and P into ATP (endergonic condensation reaction that is non spontaneous)
what is formed in glycolysis
2 ATP
2NADH
what is formed in pyruvate decarboxylation
2NADH
krebs cycle
2 ATP
6 NADH
2 FADH2
what is a trait of the mitochondrial intermembrane space
highly acidic so it can have an electrochemical gradient
chemiosmosis
use the proton electrochemical gradient- PMF to synthesize ATP
what is oxidative phosphorylation
when the ETC and chemiosmosis work together to produce ATP
oxygen is the final electron acceptor and gets reduced to form water
ETC goal
to regenerate electron carriers and create and electrochemical gradient to power ATP production
location of ETC
eukaryotes- mitochondrial inner membrane
prokaryotes- cell membrane
protein complexes I-IV move electrons through a series of redox reactions that each pump protons from matrix to intermembrane space
NADH VS FADH2
NADH is more effective, drops electrons directly at complex I, regenerating NAD+
FADH2 drops electrons off at protein complex II regenerating FAD– fewer protons are pumped bc complex I is bypassed
aerobic respiration- endergonic or exergonic?
exergonic- delta G is -686. kacl/mol glucose
how much ATP does NADH produce
3ATP but less from glycolysis bc varying amounts of ATP must be used to shuttle NADH from cytosol to mitochondrial matrix but prokaryotes dont need to shuttle
2NADH in glycolysis
euk- 4-6 ATP
prok- 6 ATP
how many ATP does FADH2 produce
2ATP
what is the reactant and product of pyruvate oxidation
2 pyruvate -> 2 acetyl coA + 2CO2+ 2NADH
using pyruvate dehydrogenase
what are the steps of pyruvate oxidation
decarboxylation- 3 c pyruvates move from cytosol into mitochondrial matrix- are decarboxylated producing CO2 and 2 carbon molecule
oxidation- 2 carbon mol is converted to acetyl group- reducing NAD+ to NADH
coenzyme A- CoA binds to acetyl making acetyl coA
krebs cycle- reactants and products
acetyl coA( 2C) and oxaloacetate (4C) make citrate (6C)
this produces
4CO2
6NADH
2FADH2
2ATP
krebs cycle steps
- Acetyl-CoA joins oxaloacetate (four-carbon) to form citrate (six-carbon).
- Citrate undergoes rearrangements that produce 2 CO2 and 2 NADH.
- After the loss of two CO2, the resulting four-carbon molecule produces 1 ATP through substrate-level phosphorylation.
- The molecule will now transfer electrons to 1 FAD, which is reduced into 1 FADH2
- Lastly, the molecule is converted back into oxaloacetate and also gives electrons to produce 1 NADH.
- Two acetyl-CoA molecules produce
4 CO2
6NADH
2 FADH2
2 ATP.`
what are the two laws of thermodynamics
- Energy cannot be created nor destroyed, but can be transformed from one form to another.
- The entropy (disorder) of the universe is always increasing. The combined change in entropy (system and surroundings) must be positive.
- The entropy of a substance at absolute zero is 0.
what is more stable, ATP or ADP
ATP is less stable bc of the addiional negatively charged phosphate group
what are the processed involved in aerobic respiration
four catabolic processes
- glycolysis
-pyruvate oxidation
-krebs cycle
-oxidative phosphorylation
where does glycolysis occur
in the cytosol
when does glycolysis occur
in both oxygenic and non oxygenic enviroments
therefore, it can be used during aerobic respiration and fermentation
substrate level phoshorylation
process used to generate ATP in glycolysis by transferring a phosphate group directly to ADP from a phosphorylated compound
glycolysis phases
energy investment phase and payoff phase
hexokinase
uses ATP to phosphorylate glucose to G6P
G6P cant leave the cell
isomerase
turns G6P to Fructose 6 phosphate
phosphofructokinase
uses second ATP to phosphorylate F6P into F6 bisphosphate
- key regulatory step in glycolysis
what happens after we make fructose 6 bisphosphate
it is broken down into DHAP and G3P (in eqm with each other)
G3P can go onto the energy payoff phase- DHAP converts to more G3P so they stay in eqm
G3P undergoes a series of redox reactions to produce 4 ATP through substrate level phosphorylation, 2 pyruvate, and 2 NADH
but since we used 2 ATP initally, our final ATP payoff is only 2
names for krebs cycle
TCA - tricarboxylic acid cycle
CITRIC ACID CYCLE
