How Energy Cycles: Photosynthesis & Cellular Respiration Biology

How Energy Cycles

How Energy is Cycled

Photosynthesis: A Review

Photosynthesis Only in plants (Some bacteria/some protists) Occurs in those cells that have  chloroplasts Chlorophyll – necessary for chloroplasts to work correctly Formula: Light + CO 2 + H 2 O  C 6 H 12 O 6 + O 2

Photosynthesis, cont. 3 (simplified) stages 1. Energy from sunlight is captured by chloroplasts 2. Light energy is converted into chemical energy by chlorophyll enzymes 3. ATP and NADPH are formed

Rate of Photosynthesis What factors do you think affect the rate of photosynthesis? Light intensity Carbon dioxide Temperature Amount of water available

Cellular Respiration * The process that releases energy by breaking down glucose and other food molecules * Occurs in ALL living cells

Understanding Cellular Respiration: First we need to understand that while photosynthesis happens in plants and some bacteria/protists (those which can have chlorophyll present), cellular respiration happens in all cells. What do most cells need to have in order for cellular respiration to take place…

Mitochondria!!: Cytoplasm: glycolysis Matrix (inner space): Prep Step and the Kreb’s Cycle Cristae (the folds): contains the carriers used in The Electron Transport System

Aerobic (Oxygen) Cellular Respiration Occurs in the presence of oxygen Major energy releasing process Occurs in 3 stages:  GLYCOLYSIS  KREBS CYCLE  ELECTRON TRANSPORT CHAIN FORMULA: C 6 H 12 O 6 + O 2  CO 2 + H 2 O + ATP What does this formula remind you of?

GLYCOLYSIS Occurs in the cytoplasm 1. Glucose converted into pyruvic acid 2. Produces a net total of 2 ATP molecules 3. 2 NADH molecules are formed 4. Does not require oxygen

Krebs Cycle (aerobic) Occurs in mitochondria Pyruvic acid from glycolysis is broken down into CO 2 1 molecule of ATP is produced ADPATP Energy released -P Energy stored +P

Electron Transport Chain The Krebs Cycle generates high-energy electrons that are passed to the electron transport chain Here they are used to change ADP to ATP Water is formed

Anaerobic Cellular Respiration  Without oxygen  Also called fermentation  Yields 2 molecules of ATP  Glycolysis is followed by either: lactic acid fermentation Alcoholic fermentation

Lactic Acid Fermentation Lactic acid produced Build up of lactic acid causes you to have sore muscles after working out

Alcoholic Fermentation Ethyl alcohol is produced Fermentation- used to make beer and wine Bread Baking- Yeast are anaerobic organisms