C9- Energy in a Cell Pp

Table of Contents Section 9.1-The Need for Energy Section 9.2- Photosynthesis: Trapping the Sun’s EnergyPhotosynthesis: Trapping the Sun’s Energy Section 9.3- Getting Energy to Make ATPGetting Energy to Make ATP

9.1-The Need for Energy Essential for life Active transport, cell division, movement, & production, transport & storage of proteins require energy. Energy molecule ATP adenosine triphosphate

Forming & Breaking Down ATP Phosphate groups are positive so they repel each other. Bonding them requires an input of energy. AMP adenosine monophosphate 1 group ADP adenosine diphospate 2 groups ATP With 3 groups, break down releases even more energy.

Forming & Breaking Down ATP ATP With 3 groups, breakdown releases even more energy. ADP-ATP cycle is renewable The cell doesn’t have to store all the energy it needs.

Forming & Breaking Down ATP When ATP is broken down to ADP, it can be released from the binding site in the protein and be made available to another ATP.

Uses of Cell Energy Making new molecules Building cell membranes & organelles To maintain homeostasis To eliminate waste Transmit nerve impulses

9.2 Photosynthesis Trapping Energy from Sunlight Process of changing sunlight to glucose in 2 steps  Light Dependent RXN converts it to chemical E in form of ATP  Light Independent RXN uses ATP to make glucose

9.2 Photosynthesis

Photosynthesis- light-dependent Occurs in the chloroplast in the membranes of the thylakoid discs Pigment chlorophyll absorbs light (reflects green)

Photosynthesis- light-dependent Energy from light is transferred to electrons Electron are passed to a series of proteins or electron transport chain Water is split to release oxygen; H ion joins carrier molecule NADP (photolysis)

Photosynthesis- light-dependent NADPH transfers energy to stroma H ions are pumped into thylakoid & provide energy for ATP or chemiosmosis Second Phase is light independent- The Calvin Cycle

Photosynthesis- light-independent oThe Calvin Cycle oSeries of carbon dioxide reactions to form sugar. oC atom from CO 2 bonds w/ 5 carbon sugar ribulose. (Carbon fixation) o6C sugar divides into 2 3C sugars

Photosynthesis- light-independent oCalvin Cycle o bonds w/ 5 carbon sugar ribulose. o6C sugar divides into 2 3C sugars oSeries of rxn convert 3C molecules into higher energy PGAL (phosphoglyceralde- hyde)

Photosynthesis- light-independent oCalvin Cycle oSeries of rxn convert 3C molecules into higher energy PGAL (phosphoglyceralde- hyde) o5 PGAL make 3 RuBP to replenish what was used so process can continue

9.3 Getting Energy to Make ATP Cellular respiration- process that mitochondria use to break down food molecules to ATP. 3 stages of respiration  Glycolysis  Citric Acid Cycle  Electron Transport Chain

Respiration Glycolysis series of chemical reactions in cytoplasm to break glucose (6C) to pyruvic acid (3C). Anaerobic process Takes 2 ATP to start glycolysis but only makes 4 ATP. Not effective

Respiration Glycolysis uses an electron carrier, NAD +, which forms NADH when it accepts 2 electrons. After glycolysis, the PGAL moves into the mitochondria where 2 more stages occur.

Respiration Citric Acid Cycle (Krebs)- another series of chem RxNs changing acetyl-CoA (2C) to form ATP & CO 2. NAD + & FAD pick up energized electrons & pass them to ETC.

Respiration Electron Transport Chain- inner membrane of the mitochondria- energized electrons are passed from protein to protein releasing energy as they go.

Respiration Electron Transport Chain- some energy is used to make ATP & some is used to pump H + into mitochondrion center Final e acceptor is O which reacts w/ H to form 2 water molecules Overall, 32 ATP made aerobicly + 4= 36 total

Fermentation Anaerobic process to produce ATP w/out oxygen during heavy exertion. Two types:  Lactic acid fermentation  Alcoholic fermentation

Fermentation Lactic Acid Fermentation- supplies energy when O is scarce 2 pyruvic acids use NADH to make 2 lactic acid molecules. 2 ATP formed for each glucose and lactic acid goes to the muscle cells & on to the liver to be broken into pyruvic acid. Lactic acid causes muscle fatigue.

Fermentation Alcoholic fermentation- used by yeast cells & some bacteria to produce CO 2 & ethyl alcohol. CO 2 produced by yeast makes bread rise.

Comparing Photosynthesis & Respiration Food synthesized Sun’s energy stored CO 2 used Oxygen given off Requires light Produces sugars Food broken down Glucose energy released CO 2 produced Oxygen used Does not need light Produces CO 2 & water