Zusammenfassung der Ressource
CH 7: How Cells Harvest Energy
- organisms classified on
how they gain energy
- HETEROTROPHS
- live on organic
compounds made
by other organisms
- AUTOTROPHS
- produce their own
organic molecules
through photosynthesis
- "troph" means to feed
- "hetero" means different
- RESPIRATION
- all organisms use some
form of cellular respiration
to extract energy from
organic molecules
- METABOLIC PROCESSES
- AEROBIC RESPIRATION
- final electron receptor
is oxygen (O2)
- energy released in
steps not all at once
- ANAEROBIC RESPIRATION
- final electron acceptor
is an inorganic
molecule (not O2)
- FERMENTATION
- final electron
acceptor is an
organic molecule
- ELECTRON CARRIERS
- OXIDATION OF GLUCOSE
- oxidation of glucose happens in stages:
- GLYCOLYSIS
- converts 1 glucose (6 carbons)
into to 2 pyruvate (3 carbons)
- net production of 2 ATP molecules
bu substrate-level phosphorylation
- 2 NADH produced by
reduction of NAD+
- NADH must be recycled
- occurs in cytoplasm
- PYRUVATE OXIDATION (PREP STEP)
- in the presence of oxygen,
pyruvate is oxidized
- EUKARYOTES
- occurs in
mitochondria
- multienzyme complex called
pyruvate dehydrogenase
catalyzes reaction
- for each 3-carbon pyruvate molecule:
- 1 carbon dioxide (CO2)
- decarboxylation
by pyruvate
dehyrdogenase
- 1 NADH
- 1 acetyl-CoA
- consists of 2
carbons from
pyruvate attached
to coenzyme A
- PROKARYOTES
- occurs in plasma
membrane
- KREBS CYCLE
- oxidizes acetyl group
from pyruvate
- biochemical pathway of
9 steps in 3 segments
- acetyl-CoA +
oxaloacetate --> citrate
- citrate rearrangement
and decarboxylation
- for each acetyl-CoA that enters:
- regeneration of
oxaloacetate
- release 2 molecules of CO2
- reduce 3 NAD+ to 3 NADH
- reduce 1 FAD (electron carrier) to FADH2
- produce 1 ATP
- occurs in matrix
of mitochondria
- ELECTRON TRANSPORT CHAIN & CEMIOSMOSIS