Cell Energy: ATP, Photosynthesis & Cellular Respiration Chapters 8 & 9

Energy for the Cell ATP= Adenosine Triphosphate 3 major parts to ATP: 1. Adenine Adenosine 2. Ribose (sugar) 3. Three phosphates

Adenosine Triphosphate

adenine three phosphates ribose

How is energy released from ATP? Break a bond between 2nd & 3rd phosphates This releases ENERGY to be used by cells!

3rd phosphate is broken off

ATP breaking down to ADP and releasing ENERGY!

ADP= Adenosine Diphosphate Only 2 phosphates instead of 3 ADP is recycled to make ATP [add a phosphate] If ADP/ATP is not reused, we would eat 24/7 just to have enough energy!

ADP being recycled to create ATP once again.

PHOTOSYNTHESIS Photosynthesis = process trapping light energy to make GLUCOSE [chemical (food) energy]

6CO2 + 6H2O + sunlight C6H12O6 + 6O2 6 carbon dioxide 6 water 1 glucose 6 oxygen

Where does photosynthesis take place? PLANTS only; in the LEAVES In plant cell, inside CHLOROPLASTS

Chlorophyll = pigment that captures light energy from sun found in THYLAKOID DISCS in chloroplasts

http://www. nicerweb. com/doc/class/bio100/Locked/media/ch06/DB06100 http://www.nicerweb.com/doc/class/bio100/Locked/media/ch06/DB06100.jpg

Why are Plants Green? Chlorophyll absorbs all wavelengths of light EXCEPT for green. Green wavelengths are REFLECTED most

Green wavelength Green not absorbed so it gets reflected – that’s why plants look green!

Photosynthesis occurs in 2 phases: 1. Light Dependent Reactions 2. Light Independent Reactions

Light DEPENDENT rxns (Occurs in thylakoids) takes light energy to make ATP & NADPH (needed for light indep. rxns) converts H2O to O2

Three Processes: a. Electron transport chain (ETC) 1) light hits chlorophyll & energizes e- 2) e- move down a chain to make NADPH (a form of energy)

b. Photolysis = splits water to make oxygen , hydrogen ions & electrons (to replace e- used in ETC) 2H2O  4H+ + 4e- + 02

c. Chemiosmosis moves H+ (made in photolysis) to stroma (space inside chloroplast) to make ATP

http://www.mun.ca/biology/singleton/Topic%2012/lPlantNutrition&Metabolism.htm

2. Light INDEPENDENT Reactions (CALVIN CYCLE) = makes glucose from CO2 using NADPH & ATP made in light dep. rxns

a. Occurs in light or dark b. Occurs in stroma c. Glucose has 6 carbons & CO2 has only 1 carbon Calvin cycle must go around 6 times to make 1 glucose

Light O2 Sugars CO2 NADPH ATP ADP + P NADP+ Chloroplast Light Dependent Reactions Calvin Cycle

CELLULAR RESPIRATION = process that breaks down glucose to make ATP occurs PLANT & ANIMAL cells

C6H12O6 + 6O2 6CO2 + 6H2O + ATP 1 glucose 6 oxygen 6 carbon dioxide 6 water

Glucose Glycolysis Oxygen present No oxygen present Aerobic Respiration Fermentation

Glycolysis – breaking down glucose into pyruvic acid occurs in cytoplasm ANAEROBIC = does not require oxygen (can still occur if O2 present)

Makes : 4 ATP Uses: 2 ATP NET TOTAL: 2 ATP

A. Aerobic Respiration = breaks down glucose to make ATP when O2 is available occurs in MITOCHONDRIA 2 major stages (after glycolysis)

1) Citric Acid Cycle (Kreb’s Cycle) – uses pyruvic acid (from glycolysis) to make ATP & CO2 occurs in MATRIX [space within mitochondria] AEROBIC = requires oxygen makes 2 ATP

2) Electron Transport Chain (ETC) – Makes H2O & ATP from O2 and H+ Occurs in CRISTAE (inner membrane) AEROBIC makes 34 ATP

38 ATP! ENERGY MADE FROM AEROBIC RESPIRATION: Glycolysis = 2 ATP Citric Acid Cycle = 2 ATP (Kreb’s Cycle) ETC = 34 ATP From 1 glucose 38 ATP!

Glucose Cytoplasm Mitochondrion Glycolysis Cytoplasm Pyruvic acid Electrons carried in NADH Krebs Cycle Electrons carried in NADH and FADH2 Electron Transport Chain Mitochondrion

B. FERMENTATION (Anaerobic Respiration) = breaks down glucose to make ATP when no O2 is available begins after glycolysis

2 major types: 1) Lactic acid fermentation –glucose breaks down to make lactic acid & CO2 makes 2 ATP (including glycolysis)

occurs in bacteria [yogurt, cheese, etc.] occurs in human muscle cells [under heavy exercise, not enough O2 – lactic acid builds up in muscles & makes you sore]

2) Ethyl alcohol fermentation –glucose breaks down to make ethyl alcohol & CO2 makes 2 ATP (including glycolysis) occurs in yeast [bread rises because CO2 bubbles formed in dough]