Cellular Respiration Flashcards
1
Q
Stepwise oxidation of glucose
A
- Start with sugars and O2
- oxidize in small steps- small activation energies to overcome body temp
- energy in forms of electrons carried by NADH– will be converted into ATP
- Result in CO2 and H2O
2
Q
2 different ways to make ATP
A
- substrate-level phosphorylation
- chemiosmotic synthesis
3
Q
substrate-level phosphorylation
A
- Enzyme takes ADP and a Phosphate from PEP
- release ATP and pyruvate (phosphate deprived PEP)
- the high energy bond of PEP has a more negative deltaG for hydrolysis of PEP than the positive deltaG of adding 3rd phosphate onto ADP–> drives the formation of ATP
4
Q
Chemiosmotic synthesis
A
- happens in the mitochondria
- Rotor embedded in the membrane of the mitochondria
- Head sticking out into the mitochondrial matrix
- higher concentration of H+ in Inintermembrane space, more positive than in mitochondrial matrix
- Concentration sends things out and causes the head to rotates around
- This rotation takes ADP + Pi and releases ATP
**The process depends on the presence of the proton (H+) gradient–> which supplies the energy
The catalytic head of ATP Synthase
5
Q
Glycolysis
A
- breakdown of large macromolecules to simple subunits
- happens in cytoplasm
- DOES NOT require oxygen
- IN- glucose, 2ATP, 2NAD+, 2Pi (phosphates) and get
- OUT 2 pyruvate, 4 ATP-2ATP (2 ATPs net), and 2 NADH
- yield- 2% (not efficient)
6
Q
fermentation leading to lactic acid
A
- if oxygen is not available
- pyruvate (from glycolysis) does not go to mitochondria
- -> take e- on NADH, and put them on pyruvate (reduced it), via enzyme lactate dehydrogenase–> get lactic acid
- Fermentation- to use an organic molecule (pyruvate) to receive electrons off of NADH to recycle NAD+ back into glycolysis –> and convert pyruvate to lactate
7
Q
ferementation leading to excretion of alcohol and CO2- Yeast
A
- glycolysis like us, and if no oxygen then fermentation
- pyruvate decarboxylase (we don’t have this)
- takes pyruvate (from glycolysis) and removes a carbon in the form of CO2–> into acetaldehyde–> CO2 released that makes bread rise
- acetaldehyde–> put 2 electrons on–> ethanol
- regenerates NAD+, which goes back and makes it keep going
(in beer- vat keeps out oxygen so fermentation occurs)
8
Q
Oxidation of Pyruvate by Pyruvate Dehydrogenase (multi-subunit enzyme complex)
A
- if oxygen is available, pyruvate (from glycolysis) is brought to mitochondria
- Pyruvate dehydrogenase decarboxylates it (part of the CO2 that you breathe out), now have a 2 carbon molecule (acetyl) and attach it to carrier molecule (CoA), at the same time, strip off some electrons and put onto NAD+ to make NADH
- begin with 2 pyruvate + 2NAD + CoA+ –> get 2 acetyl CoA, 2 CO2, 2 NADH
9
Q
Citric Acid Cycle (CAC)/Tricarboxylic Acid Cycle (TCA)/Krebs Cycle
A
- for every 1 pyruvate that comes in–> make 3NADH, 1FADH2, 1 ATP equivalent (GTP), 2 carbons lost
10
Q
Electron transport System (ETS)
A
- Inner mitochondrial membrane- ETS
- NADH comes in–> strip off e- and p+ to give NAD+ (called NADH dehydrogenase)
- Hs come off and hang out in mitochondrial matrix, electrons with energy pass some energy into complex and pumps protons from matrix to intermembrane space
- pass e- to Co enzyme Q which pumps protons, then end up with e- depleted in energy
- -> end with proton electrochemical gradient–> use gradient to make ATP
- Deprotonated NAD+ and FADH are recycled
- OXYGEN is driving force here
11
Q
ALL products of oxidative steps
A
Glycolysis
2ATP (by SLP)
2NADH (2ATP/NADH)–> 4ATP
Oxidation of Pyruvate
2NADH (3ATP/NADH)–> 6ATP
Krebs Cycle
Go around twice–> 3*2= 6 NADH (3 ATP/NADH–> so get 18 ATPs out of this from chemiosmotic synthesis)–> 18 ATP
2ATP (by SLP) (actually 2GTP) –> 2 ATP
2FADH2 (2ATP/FAD)–> 4ATP
Theoretical total= 36 ATP
Bacteria sometimes make 38ATP
12
Q
energy efficiency
A
glycolysis 2%
with the rest of oxidative steps- 38%
13
Q
Racker experiement
A
- proved that it was the proton gradient that you have to have that is powering the formation of ATP
- if no gradient–> no formation of ATP
14
Q
Endosymbiont Hypothesis (and evidence)
A
- Proposed that mitochondria originated as bacterial calls that were consumed (phagocytosis) by eukaryotic cells that had nucleus but didn’t have mitochondria
- Proposed that some bacteria could do oxidative respiration before eukaryotic cells could do it
1. Duel membrane- inner and outer mitochondrial membrane (outer membrane is more eukaryotic, inner membrane has more bacterial features)
2. Size- of bacteria
3. Replicates autonomously (divides whenever) by cell fission (divide in half)
4. Mitochondria have their own genomic DNA, and this DNA is circular (not linear)
5. Small ribosomes
15
Q
DNP
A
- makes inner mitochondria membrane leaky
- protons come out and do not do ATP synthesis
- reduces ATP made
- for weight loss–> reduces ATP made, which causes cells to breaks down more macromolecules to make more ATP (metabolic rate increases)
