Download Unit 06 Lecture Notes: Metabolism and Respiration

Unit 06 Lecture Notes: Metabolism and Respiration
1. Respiration and photosynthesis are interrelated!
A. Chloroplasts supply to mitochondria:
1)
2)
B. Mitochondria supply to chloroplasts:
1)
2)
2. Mitochondria "burn" glucose, making ATP in the process
A. Equation for respiration:
C6H12O6 +
―—
6 CO2
+
+ energy
B. The energy is used to do what?
3. Breathing and cellular respiration are related!
A. Cardiopulmonary circuit:
1) Obtain oxygen from environment using respiratory mechanism
a) Air-breathing animals use lungs
b) Water-breathing animals use gills or other respiratory epithelia
2) Respiratory mechanism delivers oxygen to blood
3) Blood delivers oxygen to tissues
4) Tissues give CO2 (waste) to blood
5) Blood gives CO2 to respiratory mechanism
6) Respiratory mechanism releases CO2 to external environment!
B. Cells then take O2 and carry out cellular respiration, CO2 being waste product
4. Cellular respiration is a redox reaction
A. "Redox" means what?
B. Energy is in the electrons which create chemical bonds
C. Oxygen take electrons from glucose, breaking oxygen-hydrogen bonds
1) Glucose is oxidized (loses electrons to oxygen)
2) Forms oxygen-hydrogen bonds of water; oxygen is reduced (gains electrons)
3) More energy in glucose than in water; energy goes to gluing ADP + P into ATP
5. Overview of Cellular Respiration
A. Glycolysis: Occurs in cytoplasm
1) Converts glucose into 2 pyruvates, yielding 2 ATPs net
B. Kreb's Cycle (Citric Acid Cycle): Occurs in matrix (fluid) of mitochondria
1) Preliminary step converts pyruvate into acetyl + CO2
Putman/Biol 160 Unit 06 Lecture Notes/20130201/Page 1
2) Acetyl converted into hydrogens, electrons and CO2
3) ATP produced
4) Hydrogens and electrons taken by NAD and FAD to oxidative phosphorylation
C. Oxidative Phosphorylation: Occurs in inner membrane (crista) of mitochondria
1) Electrons from NADH and FADH2 passed through membrane to O2 (final electron
acceptor).
a) Flow of electrons used to pump hydrogens out into intermembrane space.
b) Hydrogens flow back through enzyme, energy produced fixes Ps onto ADPs
making ATPs
6. Detailed overview of cellular respiration
A. See class notes!
7. GLYCOLYSIS
A. Phase 1
1) Glucose (6 C) into two G3P (3 C each)
2) Requires 2 ATP
3) Phosphofructokinase
a) Inhibited by citric acid & ATP
b) Why is fructose bad?
B. Phase 2
1) Two G3P into two pyruvates
2) Makes 4 ATP via substrate level phosphorylation
3) Makes 2 NADH+H from 2 NAD
a) Thus NADs are required for glycolysis to occur!
b) Get NADs from
1. Oxidative phosphorylation if sufficient O2
2. Fermentations if insufficient O2
4) Fate of the two pyruvates:
a) If insufficient O2, go to fermentation
b) If sufficient O2, transported into mitochondria (pyruvate transporter)
1. Pyruvate dehydrogenase enzyme, catalyzes
a. NAD removing two hydrogens from pyruvate
b. CO2 removal from pyruvate, forming acetyl
c. Joining acetyl to CoA
8. KREB'S CYCLE
A. Acetyl-CoA enters Kreb's cycle
1) Oxaloacetate joins with acetyl, forming citrate
a) CoA goes back to get another acetyl...
b) Inhibits step 3 of glycolysis (phosphofructokinase)
2) Oxidized into two CO2s
3) Hs and electrons to go form NADH & FADH2
a) They go to oxidative phosphorylation (electron transport chain)
Putman/Biol 160 Unit 06 Lecture Notes/20130201/Page 2
9. OXIDATIVE PHOSPHORYLATION (= Electron Transport Chain)
A. Membrane proteins receive Hs and electrons from NADH & FADH2
B. Electron flow from protein to protein in membrane powers pumping of Hs out into
intermembrane space.
1) Forms hydrogen gradient (lots of Hs outside, few inside)
C. O2 is final electron acceptor; must have O2 to allow electron flow!!!
1) Accepts electrons and forms
D. Hydrogens then flow through ATP synthase.
1) Gradient (kinetic energy!) of Hs powers phosphorylation of ADP to ATP.
E. Effects of poisons on oxidative phosphorylation
1) Rotenone
a) Use: Broad spectrum insecticide and piscicide
b) Effect:
2) Cyanide
a) Use: HCN in warfare; NaCN rat poison; tobacco smoke
b) Effect: Blocks
c) Note: CO has same effect
3) Oligomycin
a) Use: Topical antifungal agent
b) Effect: Blocks ATPsynthase H+ channel
10. Recap of cellular respiration
A. With O2, makes 36 ATP
B. W/o O2, makes
1) In order to make ATP without O2, you must do two things:
a)
b)
11. Fermentations
A. What two important things do fermentation do (which allow ATP production w/o O2)?
B. Types
1) Lactic acid
a) Occurs
1. Most animal cells
2. Some bacteria (example
Putman/Biol 160 Unit 06 Lecture Notes/20130201/Page 3
b) Converts pyruvate into lactate
c) Generates NAD+
d) When do muscles go anaerobic?
2) Alcoholic
a) Yeasts and some bacteria
b) Converts pyruvate into CO2 + acetaldehyde, acetaldehyde into ethanol
c) Requires NADH, produces NAD+
d) When do yeasts go anaerobic?
e) Why do you have to cover container when making beer or wine?
12. Fuels for cellular respiration
A. Carbohydrates enter in glycolysis
1) Glucose
2) Fructose enters after phosphofructokinase regulatory step
B. Lipids
1) Glycerol enters as G3P
2) FAs enter Kreb's as acetyl
C. Amino acids
1) Deaminated by liver
2) Carboxylic acids turned into
a) Pyruvate or
b) Acetyl or
c) Kreb's cycle components
13. Cellular respiration provides materials for biosynthesis!
A. Glycolysis can synthesize
1) Glucose and other carbos
2) Glycerol from
3) Some amino acids
B. Acetyl CoA can synthesize
1) Fatty acids
2) Some amino acids
C. Kreb's cycle can synthesize
1) Some amino acids
D. How can the body make glucose if it doesn't get enough from foods?
E. How can you gain weight and store fat on a low-fat diet?
Putman/Biol 160 Unit 06 Lecture Notes/20130201/Page 4