Download Respiration: Harvesting Chemical Energy

Respiration: Harvesting Chemical Energy
Metabolism and Respiration
A. Catabolism
1. Processes that break down compounds and produce
ATP and energy
B. Anabolism
1. Processes that produce more complex molecules and
consume ATP
C. Cellular Respiration
1. Breaks down complex molecules to CO2, H2O and energy
a. Energy is used in the form of ATP
2. Provides the carbon skeletons necessary for anabolic processes
3. Raw Materials
a. Carbohydrates
b. Fat
c. Protein
4. Net reaction
C6H12O6 + 6O2
Æ
6CO2 + 6H2O + energy
The Stages of Cellular Respiration
A. Glycolysis
1. Glucose breaks into two 3-carbon molecules
B. Krebs Cycle
1. 3-carbon molecules are broken down into CO2
C. Electron transport system
1. ATP is synthesized
D. Formation of water
E. Hydrogen carriers
1. NADH NADPH
FADH2
Glycolysis
A. Formation of pyruvate (3-carbon molecule)
1. Phosphates are added to glucose by ATP
2. Carbon chain breaks into two 3-carbon chains
B. Products of Glycolysis
1. Two molecules of ATP (net)
2. Two molecules of NADH
3. Two molecules of pyruvate
C. Aerobic (with oxygen)
1. Pyruvate enters the mitochondria and 38 ATP molecules are
produced
D. Anaerobic (without oxygen)
1. In animals:
1. pyruvate forms lactic acid
2. two ATP are produced
2. In bacteria and yeast:
1. pyruvate forms alcohol
Mitochondria and Respiration
A. Mitochondria
1. Powerhouses of the cells
2. Vary in number in cells from 10 to several thousand
B. Structure
1. Outer Membranes
a. regulates movement of molecules in and out
2. Inner Membrane
a. infoldings of the inner membrane called Cristae
b. enxymes for
(1) electron transport
(2) ATP formation
(3) some of the krebs cycle
3. Matrix
a. inside area of mitochondria where most of Krebs cycle
takes place
The Krebs Cycle
A. Acetyl CoA
1. Pyruvate is converted to acetate
2. Acetate is converted to Acetyl CoA
3. Acetyl CoA enters the Krebs Cycle
B. Krebs Cycle
1. Acetyl CoA enters cycle by joining with 4-carbon oxaloacetate
to form 6-carbon citrate
2. Cycle removes two carbons in the form of CO2
a. Produces 1ATP, 3NADH, 1FADH2
3. Oxaloacetateis available to react with another acetyl CoA
Electron Transport System
A. Cytochromes
1. Enzymes and other proteins in cristae that separate hydrogen
atoms into protons and electrons
H
Æ
H+ + e-
B. Electrons
1. Release free energy through several steps
C. Protons
1. Combine with oxygen to form water in the last step
Oxygen, Respiration and Photosynthesis
A. Importance of Oxygen
1. Cellular respiration in anaerobic without oxygen
2. Only a fraction of the energy of glucose can be made
available to the cell
B. Balance Cycle
1. Respiration produces CO2 and H2O
a. Raw materials for photosynthesis
2. Photosynthesis produces glucose and O2
a. Raw materials for respiration
The Krebs Cycle in Metabolism
A. Fat Metabolism
1. Fat is converted to Acetyl CoA
a. Oxygen is necessary to get energy from the process
B. Protein Metabolism
1. Amino acid backbones can be used to assemble carbon chains
a. must be deaminated (nitrogen removed)
b. energy inefficient
C. Synthesis
1. Carbon backbones from Krebs Cycle are used in making many
important molecules
Respiration and Heat Production
A. Brown Fat
1. High number of mitochondria designed for rapid heat production
2. Common in mammals born hairless
a. On back of the neck and between the shoulders
B. Heat in plant respiration
1. Heat may convert compounds to gases that attract insects
Control of Respiration
A. High energy demand
1. Cells convert glucose to ATP
B. High energy demand, low glucose
1. Cells convert glycogen to glucose
C. Low energy demand
1. Glucose Æ
glycogen Æ
fat