2.3

Carbohydrates are the first nutrients most organisms catabolize for energy.. What if there is no food? Most organisms possess alternate metabolic pathways. Proteins, lipids, and nucleic acids can be used for cellular respiration.

Protein Catabolism Deamination: amino groups removed from amino acids. Converted to ammonia, a __________ product in animals and a useful byproduct in plants. Other parts of amino acids converted to components of glycolysis or the Krebs cycle Depends on the amino acid Leucine: acetyl-CoA Alanine: pyruvate Proline: alpha-ketoglutarate

Lipid Catabolism (1) Triglycerides first digested into glycerol and Fas. Gluconeogenesis: glycerol converted into glucose, or DHAP  G3P. Fatty acids transported into the matrix Beta-oxidation: 2C acetyl groups removed from fatty acids and then added to coenzyme A  acetyl CoA

Lipid Catabolism (2) c Lipids are harder to break down than carbohydrates Requires energy input Yields more energy (about 2x as much)

Anaerobic Pathways Glycolysis can occur in the absence of oxygen Build-up of NADH  limited NAD+  glycolysis will come to a halt. Usually ETC oxidizes NADH to NAD+, but oxygen is needed. Fermentation: transfer of hydrogen atoms of NADH to organic molecules instead of ETC Ethanol fermentation Lactate Fermentation

Ethanol Fermentation NADH passes hydrogen atoms to acetaldehyde  ethanol. Used in alcoholic beverages NAD+ can be recycled and glycolysis can continue. 2 ATP molecules may satisfy the organism’s energy needs. Yeast: single-celled fungi Breads, pastries, wine, beer, liquor, soy sauce.

Bread: Yeast + starch + water Yeast ferment glucose from Starch and release CO2 and Ethanol. CO2 makes bread rise Ethanol evaporated Wine: Yeast ferments grape & fruit sugars Fermentation ends when concentration of ethanol reaches approx. 12%  yeast cells die. Flooded Plants Undergo ethanol fermentation in the roots. Do not overwater Sally!

FAS Read the section on page 120 on fetal alcohol syndrome. What do you think?

Lactate (Lactic Acid) Fermentation Used during strenuous exercise. Muscle cells used glucose faster than oxygen can be supplied. NADH transfers hydrogen atoms to pyruvate in the cytoplasm  lactate(NAD+ is regenerated) Allows glycolysis to continue. Accumulation of lactate: stiffness, soreness, and fatigue. Lactate  bloodstream  liver. When strenuous exercise ceases, lactate  pyruvate  Krebs Cycle

Exercise Physiology Branch of biology that deals with body’s biological responses to exercise. Aerobic fitness: ability of the heart, lungs, and bloodstream to supply oxygen to the cells of the body. Maximum Oxygen Consumption (VO2 max): The maximum volume of oxygen, in mL, that the cells of the body can remove from the bloodstream in one minute per kg of body mass while the body experiences maximal exertion. Muscle cells need energy to contract ATP production will be increased if more oxygen is absorbed and used by the cells. For humans: forced to run on a treadmill and data collected. Individuals with higher VO2 max values are considered more aerobically fit than those with lower values.

VO2 max of athletes of different sports

Increasing VO2 Max Exercise and training Harder, more frequent, and longer durations Genetic variation (not everyone can be an elite athlete) Decreases with age.

Seatwork/Homework PPs page 124 #1,2,3,7,8,9,10.