cellular respiration Flashcards
cellular respiration
- opposite of photosynthesis
- depends on O2 (aerobic)
- extracts energy from food (glucose and others)
- yields 34-38 atp
4 parts of mitochondria
- outer membrane
- inner membrane
- matrix
- intermembrane space
glucose
- only 40% of E in glucose gets stored as atp
- 60% is lost as heat to environment
- glucose is completely broken down into CO2 and H2O
electrons
- glucose’s energy is stored as e-
- during cellular respiration, e- are transferred to various receptors, such as oxygen
- you can’t see the transfer of e-, just the H distribution (representation of e- transfers)
redox
reduction/oxidation reaction
oxidation
loss of e- or H+
reduction
gain of e- or H+
coenzymes
NAD+ (nicotinamide adenine dinucleotide)
FAD (flavin adenine dinucleotide)
CoA (coenzyme A)
enzymes
- dehydrogenase
- NAD (oxidized) -> NADH (reduced)
5 stages of glucose breakdown
- glycolysis
- acetyl CoA
- Krebs cycle / citric acid cycle
- electron transport
- chemisomosis
location of glycolysis
cytosol
location of acetyl CoA
matrix
location of Krebs/cac
matrix
location of electron transport
inner membrane
location of chemiosmosis
intermembrane space, inner membrane and matrix
products of glycolysis
- net 2 ATP
- 2 NADH
- 2 pGAL/G3P
- 2 pyruvic acid / pyruvate
glycolysis
all organisms do this
irreversible
phosphofructokinase
regulates glycolysis in step 3
ATP inhibits phosphofructokinase
acetyl CoA step
- 2 oxygen pulls off a C and leaves as CO2
- 2 NADH
- ES complex, acetyl CoA
Citric Acid / Krebs Cycle
- 6 NADH
- 2 FADH2
- 4 ATP
- 4 CO2
Krebs Cycle
- lies at the intersection of anabolism and catabolism
- high ATP = anabolism
- low ATP = catabolism
electron transport
- the pathway of an electron from one carrier to another
- electrons are released when a carrier becomes oxidized
- mitochondria in eukaryotes and cell membrane in prokaryotes
electron transport chain
- cytochrome
- special membrane proteins that transport electrons
cytochrome
special membrane proteins that transport electrons
intermembrane vs matrix
- matrix has low H+
- matrix is constantly being drained of its H+
- this creates an electrochemical gradient
NADH and FADH2
- for every 1 NADH and FADH2, 3 H+ move into the intermembrane space against the concentration gradient without ATP
- 10 NADH = 30 H+ removed
ATP synthase
- (aka ATP synthetase)
- because of the gradient, ATP wants to go back into the gradient
- the only way back is through a protein complex called ATP synthase
- the outflow of H+ works like a turbine and actually uses the free energy to change ADP back to ATP
oxidative phosphorylation
- the energy from all the Cs is transferred to phosphorous bonds in ATP
- chemiosmosis only
how much ATP?
- glycolysis: net 2
- acetyl CoA: 0
- Krebs: 2-4
- E- transport: 0
- chemiosmosis: 28-32
- total: 30-38
why does atp synthesis vary in chemiosmosis
- NADH and FADH2 don’t always donate 2 e = less
- they may not have picked up 2 e in the first place = less
- more than 10 NADH or FADH2 may be involved = more
poisons that interrupt cellular respiration
insecticides
antibiotics
research to understand mechanisms
anaerobic
- no oxygen
- some prokaryotes require this (Clostridium botulinum)
- can show up in muscles while exercising
lactic acid fermentation
- fermentation (cytoplasm)
- must use pyruvate to reduce NADH and NAD+
- lactic acid (lactate) produced
- if O2 is added it will switch to the Krebs cycle
uses of lactic acid fermentation
- used to make cheese
- turns soy beans into soy sauce
- cabbage turns into sauerkraut
alcohol fermentation
- yeast/bacteria
- converting pyruvate to CO2 (bubbles) and ethanol
- yeast: alcoholic beverages
- wine: yeast dies at 14% (alc)
strict aerobes
must have oxygen
strict anaerobes
must be without oxygen (stagnant ponds / deep in soil)
facultative anaerobes
can go back and forth between O2 and no O2
other organic molecules for fuel
- digestion breaks polymers to monomers, enzymes change monomers into intermediates for cellular respiration
- simple sugars -> glucose and isomers
- fatty acids -> acetyl CoA
- amino acids -> pyruvate, acetyl CoA, Krebs cycle
