Metabolism
What is metabolism?
Sum of all chemical reactions; Converting fuel to energy
What is phosphocreatine?
Holds a phosphate (Pi) that can be transferred to ADP in a single step
What is glycolysis? Where does it occur in a cell?
Breakdown of glucose
Occurs in cytoplasm
Where does aerobic metabolism occur? What is required for aerobic metabolism to occur?
mitochondria
Pyruvate is broken down to CO2 and energy is released
Glucose -->Pyruvate -->Ac-CoA -->Citric Acid Cycle --> Electron Transport Chain --> ATP Synthase
What role does oxygen play in the electron transport chain?
Final electron acceptor is O2
Reduced to H2O by 4 electrons
What is the difference between anabolic and catabolic processes?
A: build up; energy absorbed
C: break down: release energy
Write the equation for the ATP-PC system
PC + ADP <--> ATP + C
What is the net production of ATP and NADH from a molecule of glucose in glycolysis?
2 ATP and 2 NADH
What is the transition step?
Pyruvate --> Acetyl-CoA + CO2 + NADH
What does ATP synthase do? Where does it get the energy for this work?
Enzyme embedded in the mitochondrial inner membrane
Contains a channel that allows H+ to re-enter matrix
H+ flows “downhill”
Harnesses energy to generate ATP
H+intermembrane space + ADP + Pi --> H+matrix + ATP
What is energy?
Capacity to do work
W= Fxd
Under what condition does the muscle make phosphocreatine?
At rest: ATP is broken down to produce phosphocreatine and ADP (right to left)
What are the two molecules that pyruvate can be converted to? What is the determining factor between the two reactions?
Acetyl-CoA (O2)
Lactate (no O2)
What is produced by the citric acid cycle? Why are two “turns” of the citric acid cycle required to metabolize glucose?
Ac-CoA --> 2 CO2 + 3 NADH + FADH2 + ATP (1 turn)
2 turns per glucose (because 2 acetyl-CoA come from glycolysis)( think 2 pyruvate were formed so they both have to have a turn)
How many molecules of ATP can be produced from one molecule of glucose via aerobic metabolism?
Total 32 ATP per molecule of glucose
What is the body’s energy currency? Write an equation to show how it works.
ATP
ADP + Pi + energy <--> ATP
Under what condition does it use phosphocreatine?
During exercise: ATP is produced from phosphocreatine and ADP (left to right)
What happens to lactate that is formed in a muscle fiber? What happens to NADH/NAD+ when lactate is formed?
Lactate is released to the blood
NAD+ is regenerated
What are NADH and FADH2?
NADH and FADH2 donate electrons
What pathway provides extra ATP when a person increases exercise intensity?
anaerobic glycolysis supplements aerobic metabolism
When is each pathway an important source of ATP?
ATP-PC
Immediate
Anaerobic glycolysis
Short term
Aerobic metabolism
Long term
For how long can the ATP-PC system provide energy during exercise?
•Very short term – about 10 seconds, a maximum of 30 seconds
What is the electron transport chain? What work does it do?
ETC releases energy that is used to pump protons (H+) “uphill” out of the matrix into the intermembrane space
5 carriers (or cytochromes) receive and then donate electrons
They are reduced (gain electrons) and then oxidized (lose electrons)
Each step releases energy
What are the effects of aerobic and anaerobic exercise training?
Aerobic training increases the amount of oxygen that can be consumed
Increase in VO2max (maximal oxygen consumption)
More mitochondria
Bigger mitochondria
Increased enzyme efficiency
Better blood flow