Respiration (3) Flashcards
Aerobic respiration creates about ____ ATP
30-32 ATP
Respiration occurs in which 4 processes?
Glycolysis, Acetyl Coa formation, Krebs cycle, Oxidative phosphorylation
Where does glycolysis occur?
cytoplasm
Where does Acetyl CoA formation occur?
mitochondria
Where does Krebs cycle occur?
mainly matrix
Where does oxidative phosphorylation occur?
inner membrane of mitochondria
Reduction definition
loss of oxygen or gain of electrons
Oxidation definition
gain of oxygen or loss of electrons
Respiration is an (oxidation/reduction) process
oxidation
A reducing agent (accepts/donates) hydrogen/electrons
donates e-
An oxidizing agent (accepts/donates) hydrogen/electrons
accepts e-
In respiration glucose is the (oxidizing/reducing) agent
reducing agent
In respiration 6O₂ is the (oxidizing/reducing) agent
oxidizing agent
NAD⁺ (4 facts)
- is an electron carrier 2. has one positive charge 3. can carry 2 electrons and 1 proton 4. transfers electrons gained in the oxidation of glucose to drive ATP synthesis
NADH
transfers electrons at a high energy level, creates ~ 3 ATP per NADH
NAD⁺ is a(n) ____ agent
oxidizing agent (accepts e-)
NADH is a(n) ____ agent
reducing agent (donates e-)
FAD transfers electron from ___ to the electron transport system
citric acid cycle
FADH₂ transports at a ____ energy level than NADH, and makes ~ ____ ATP per FADH₂
lower, 2
substrate level phosphorylation creates ATP by ____
transfering a phosphate from a high-energy phosphate compound to ADP by kinases
when does substrate level phosphorylation occur and where
during glycolysis in the cytoplasm
substrate level phosphorylation is (aerobic/anaerobic)
anaerobic fermentation
Where does oxidative phosphorylation occur?
In the inner and intermembrane space of the mitochondria in eukaryotic cells. In prokaryotic cells it occurs in the plasma membrane.
Chemiosmotic theory (by Peter Mitchell)
NADH or FADH₂ transfers electrons taken from food molecules and through the electron transport chain to be accepted by O₂.
Electron transport chain (def)
A series of membrane proteins
Oxidative phosphorylation
NADH or FADH₂ transport electrons taken from food molecules through the electrons transport chain and accepted by O₂. (H⁺ are pumped into the intermembrane space of the mitochondria from the matrix creating a [H⁺] gradient.)
Membrane protein (def)
a proton pump that creates a proton gradient
H⁺ gradient
proton gradient formed from differences in proton concentrations between the inside and outside of a membrane.
ATP synthase
a membrane protein complex that creates ATP by combining ADP with Pi.
When the H⁺s return to the matrix through ATP synthase it releases an ATP.
Pi
inorganic phosphate
Proton motive force
H⁺s returning to the matrix because of their concentration gradient.
glycolysis (simple def)
the breakdown of sugar
glycolysis (short process)
- occurs in the cytoplasm
- 2 stages
- first stage is energy investing (2 ATP are used to break down glycolysis into 2 two trioses)
- second stage is where 4 ATP, 2 pyruates, and 2 NADH are formed
Hexokinase
phosphorylation enzyme that phosphorylates glucose (step 1 of glycolysis)
Phosphofructokinase
kinase that phosphorylates a phospho-fructose.
- complex allosteric enzyme
- enzyme that needs Mg ²⁺
- phosphorylyses fructose 6-phosphate (step 3 of glycolysis)
- can be inhibited by citrate?
What is the key regulatory step of glycolysis?
- step 3
- phosphorylation of fructose 6-phosphate
- also uses ATP like step 1
What is the key regulatory enzyme of glycolysis?
Phosphofructokinase
- because it can make the reaction go faster, slower, or stop
What is the first commited step of glycolysis?
Step 1: glucose is phosphorylated by hexokinase into glucose 6-phosphate
Arsenate poisoning
Competes with PO4^2- for -SH site, creates inhibition so no ATP is made
What are the imputs of glycolysis (4)?
- glucose
- 2 ATP
- 2 NAD⁺
- 2 ADP
- 2 Pi
What are the outputs of glycolysis (4)?
- 2 pyruvate
- 2 NADH
- 2 H⁺
- 2 ATP (net)
Glycerol 3-phosphate shuttle
NADH from cytoplasm transfers electron to DHAP to form glycerol 3-phosphate that enters mitochondria to form FADH2 and DHAP from FAD.
- only makes 2 ATP per NADH
Malate-Aspertate shuttle
In heart and liver cells, NADH transfers electron to mitochondria NADH through malate-aspertate, making 3 ATP per NADH per glycolysis
Acetyl CoA formation
Pyruvate from glycolysis is transported to the mitochondria to be oxidized by the pyruvate dehydrogenase complex into acetyl CoA
- can also be generated through fats and oxidative phosphorylation
- irreversible and highly regulated process
- Acetyl CoA is a common intermediate that can be gotten from carbohydrates, lipids, and proteins
Acetyl CoA reactants and products
R: pyruvate, CoA, NAD+
P: Acetyl CoA, CO2, NADH
What is the first commited step of the Krebs Cycle?
- first step
- performed by citrate synthase
- induced by AMP
- inhibited by ATP
Krebs Cycle first commited step reactants and products?
R: Acetyl CoA, Oxaloacetate, H2O
P: Citrate, CoA, H
Krebs Cycle step 3
- rate limiting step
- Oxidative dicarboxylation of isocitrate by isocitrate dehydrogenase
- stimulated by ADP
- inhibited by high levels of NADH and ATP
Krebs Cycle step 3 reactants and products?
R: Isocitrate, NAD+, H+
P: Ketoglutarate, NADH+, CO2, H+
Krebs Cycle reactions inputs
Acetyl CoA, 3NAD+, FAD, ADP, Pi, 2H2O
Krebs Cycle reactions outputs
2CO2, 3NADH, 3H+, FADH, ATP, CoA
ATP/ADP Translocase
A proton transports the ATP released from the matrix to the cytoplasm through the membrane protein ATP/ADP translocase
What are the three types of respiratory poisons?
1.) Uncouplers of proton gradient
2.) ATP synthase inhibitors
3.) Electron transport inhibitors
Uncouplers of proton gradient (def)
get rid of proton gradient by making the membrane leaky, stops ATP from being made
ATP synthase inhibitors (def)
binds to ATP synthase and inhibits ATP synthesis
Electron transport inhibitors (def)
blocks the electron transport
causes reduced or lack of protein gradient
stops the regeneration of NAD+ and FAD so Krebs cycle cannot function
Alcohol fermentation
2 pyruvates (from glycolysis) are decarboxylated to make acetaldehyde, which is hydrogenated to form ethanol using NADH as the reducing agent.
This regenerates NAD+ allowing glycolysis to continue
Pasteur effect
yeast growing under anaerobic conditions consume more sugar than yeast growing under aerobic conditions
this is because yeast growing under anaerobic conditions also produce less ATP
Lactic acid fermentation
animals do not have pyruvate decarboxylase so they do this instead.
NAD+ is regenerated by converting the pyruvate into lactate to be taken to the liver to be converted to glucose for later use
