Cellular respiration -Animal cells take sugar (glucose) made by plants during photosynthesis & break it down for E. Process uses enzymes and e- carriers to convert glucose into intermediate products.

As products are formed, E is released Process occurs SLOWLY as glucose Δ’s from 1 product to another so E won’t be released once & be lost as heat or light.

Chemical Energy and Food 1 g. of sugar glucose releases 3800 calories of heat E. calorie- amt of E needed to raise temp of 1 g. of water 1 Celsius degree. The Calorie (capital C) on food labels = 1 kilocalorie (1000 calories.)

The process -There are 2 phases -1 st - Anaerobic respiration (glycolysis) *does NOT require oxygen *takes place in cytoplasm

-2 nd - Aerobic respiration *requires oxygen *takes place in the mitochondria *glucose is completely broken down

1 st -Glycolysis occurs in cytoplasm Converts glucose to pyruvic acid = anaerobic stage= glycolysis releases 2 ATP

If O present, glycolysis leads to Kreb cycle & electron transport chain releasing 34ATP &CO 2.

No O present- leads to fermentation, only releasing some E

2 nd- Kreb & electron transport If O present will go into this phase Process moves into mitochondria & enters Krebs cycle. Pyruvic acid is broken down into smaller & smaller compounds, releasing E w/ each breakdown. Results in 34 ATP and CO 2 38% of total E in glucose is used for cell processes, 62% is lost as heat for body temp & exercise.

No O present The 2 main types of fermentation are alcoholic fermentation and lactic acid fermentation. After glycosis, if no O present - pyruvic acid is converted into ethyl alcohol & CO 2 plus E in organisms such as yeasts –pyruvic acid is converted into lactic acid & small amount of E. Occurs in animal cells (ie. Muscle). Too much lactic acid causes the burning sensation or cramping! (see activity)