Chapter 5
Cell Respiration and Metabolism
Glucose:
l Cellular respiration: glucose is broken down to form ______
– Requires oxygen =
– Lack of oxygen =
• Forms ______as the end product
Metabolism
l Divided into 2 categories:
– Catabolic:
• ______.
• Breakdown larger organic molecules into smaller molecules.
• Serve as primary sources of energy for synthesis of ______
– Anabolic:
• Require ______of energy.
• Synthesis of large energy-storage molecules.
Glycolysis = ______
l Metabolic pathway by which glucose is converted to ______molecules of ______.
l Glucose must be ______first before energy can be obtained.
– ______consumed at the beginning of glycolysis.
l Net gain of 2 ATP, 2 NADH, + 2 H+.
Lactic Acid Pathway
l Metabolic pathway by which glucose is converted to lactic ______
– Oxygen is ______used in the process.
l Produce ______molecule.
Lactic Acid Pathway (continued)
l Some tissues better adapt to anaerobic conditions:
– ______do not contain mitochondria and ______use the lactic acid pathway.
– Occurs in ______and ______when ratio of oxygen supply to oxygen need falls below critical level.
• Skeletal muscle:
– Normal daily occurrence.
– Does not harm muscle tissue.
• Cardiac muscle normally respires ______:
– ______occurs under anaerobic conditions.
Glycogenesis and Glycogenolysis
l Cells cannot store many ______molecules.
l Increased intracellular ______increases ______pressure, drawing ______into the cell.
l Many organs must store ______in form of ______.
– Glycogenesis: ______
– Glycogenolysis: ______
Glycogenesis and Glycogenolysis (continued)
l ______cannot leak out of the cell.
l ______generate glucose-6-phosphate for own glycolytic needs.
l Liver contains the enzyme ______that can remove the phosphate group and produce free glucose.
Aerobic Respiration
l The ______formed by glycolysis enters interior of ______
l Converted by ______to 2 molecules of ______
l Acetyl CoA serves as substrate for mitochondrial enzymes in the aerobic pathway.
Krebs Cycle (Citric Acid Cycle)
l Acetyl CoA subunit combines with oxaloacetic acid to form ______
l Citric acid enters the ______.
– Through a series of reactions, citric acid is converted to ______to complete the pathway.
l Produces:
l 1 GTP, 3 NADH, and 1 FADH2
– NADH and FADH2 transport ______to Electron Transport System (ETC).
Krebs Cycle (Citric Acid Cycle) (continued)
Electron Transport and Oxidative Phosphorylation
l Cristae of inner ______membrane contain molecules that serve as an electron transport system during aerobic respiration.
– Electron transport chain consists of ______), coenzyme Q, and cytochromes.
– Each ______transfers electron pairs from NADH and FADH2 to next cytochrome.
• Oxidized NAD and FAD are regenerated and shuttle electrons from the ______Cycle to the ETC.
l Cytochrome receives a pair of ______.
– ______reduced, then oxidized as electrons are transferred.
Electron Transport
l Cytochrome a3 transfers electrons to O2 (final electron acceptor).
l Oxidative phosphorylation occurs:
– Energy derived is used to ______to ATP.
ATP Balance Sheet
l Direct substrate phosphorylation (glycolysis):
– Net gain of ______.
l Oxidative phosphorylation:
– 2.5 ATP produced for pair of electrons each NADH donates.
– 1.5 ATP produced for each pair of electrons FADH2 donates (activates 2nd and 3rd proton pumps).
– Net of ______ATP produced.
Lipid Metabolism
l When more energy is taken into the body faster than consumed, ______
l Glucose converted into ______..
Lipogenesis
l Formation of ______
l ______subunits from acetyl CoA converted into various lipids.
l Occurs mainly in ______
Lipid Metabolism
l Lipolysis:
– ______
l Triglycerides:______
l ______serve as blood-borne energy carriers.
– Free fatty acids serve as the ______source derived from triglycerides.
Breakdown of Fat: Beta-Oxidation
l Enzymes remove ______acetic acid molecules from acid end of fatty acid chain.
– Forms ______
l Acetyl CoA enters ______.
– ______
Brown Fat
l Amount of brown fat ______.
l Major site for ______in the newborn.
l Brown fat produces an uncoupling protein, ______to leak out of inner mitochondrial membrane.
– Less ______produced, causes electron transport system to be more active.
Ketone Bodies
l ______in adipose tissue broken down and resynthesized.
– Ensure the blood will contain sufficient levels of ______for aerobic respiration.
• May be hydrolyzed to ______.
l If ______sufficient, acetyl CoA channeled into alternate pathway.
– Converted to ______bodies.
Amino Acid Metabolism
l Nitrogen is ingested primarily as ______
l Excess nitrogen is excreted mainly as ______.
l Nitrogen balance:
– ______
l ______N balance:
– Amount of nitrogen ingested more than amount excreted.
l ______N balance:
– Amount of nitrogen excreted greater than ingested.
l In healthy adults the amount of nitrogen excreted = amount ingested.
Transamination
l Adequate amounts of ______are required for ______and repair. A new amino acid can be obtained by ______.
l N = ingested as proteins via ______
l N = excreted mainly as ______
l Excess ______: body takes off N, uses C skeleton for energy/fat
l See figure 5.16
Essential vs Nonessential AA
l Essential Nonessential
l 1. Arginine 1. Alanine
l 2. Histidine 2. Asparagine
l 3. Isoleucine 3. Aspartic Acid
l 4. Leucine 4. Glutamic Acid
l 5. Methionine 5. Glutamine
l 6. Phenylalanine 6. Glycine
l 7. Threonine 7. Proline
l 8. Tryptophan 8. Cysteine
l 9. Valine 9. Serine
l 10. Lysine 10. Tyrosine
Uses of Different Energy Sources
l Not all cells can use ______as the energy source.
l Blood contains a variety of energy sources:
– ______
l Brain uses ______as its major source of energy.
– Blood [glucose] maintained as many organs spare glucose.
Uses of Different Energy Sources (continued)