Honors: Ch. 6 Cell Respiration - Review Topics
Introduction
- Energy needs in cells, ATP- ADP cycle
- Aerobic, anaerobic – organisms, pathways, energy yield
- Interplay with photosynthesis: reactants, products,energy
- Gas exchange, glucose delivery and entry into cells
- Calorie, amount in carbs, fats, and proteins
Mitochondria – compartments, sites for reactions
NAD, FAD - Hydrogen/electron acceptors, their role
3 pathways – where is each in cell, energy yield
Aerobic Respiration
Glycolysis - In cytoplasm
- Uses 2 ATP; glucose splits
- Forms 2 pyruvic acid (3 C)
- forms 4 ATP, NADH
- Net yield: 2 ATP
Krebs Cycle (Citric Acid cycle)
- In mitochondrial matrix
Prep: pyruvate forms acetyl CoA and CO2
Cycle Completes glucose breakdown
- 4-carbon oxaloacetate recycles
- NAD+ FAD take H+ and e- from glucose
- Yield: 1 ATP each cycle, 2 per glucose
Electron Transport Chain – In cristae
- chemiosmosis
- NADH and FADH2 release H and e-
- e- passed along series of acceptorproteins
- H+ gradient powers ATP synthesis
- OXYGEN + e- + H+ H2O
- Yield: 32-34 ATP/glucose
Chemiosmosis
- energy from e- pumps H+ across membrane
- H+ concentrate in space between membranes
- H+ diffuse through ATP synthase to make ATP
Total energy from one glucose = 36 ATP
AnaerobicRespiration – when oxygen is NOT present
- in cytoplasm
- Glycolysis is followed by fermentation
- No additional ATP made (2 made in glycolysis)
- NAD+ is returned, can be used again
Lactic acid Fermentation: pyruvic acid lactic acid (or other acids)
- Some bacteria
- Muscle cells – only temporarily
- Oxygen debt – muscles cramp and burn – need oxygen
Alcohol Fermentation
- Yeast
- Makes ethyl alcohol and CO2
Other Foods
- Digested to monomers first (must be small enough to enter cells)
- Fats – burned after glucose and glycogen used up
- Proteins – last choice, needed for other roles
- make nitrogen wastes, strain kidneys and liver
Foods NOT used for energy
raw materials to make other biologic molecules in biosynthesis