PHOTOSYNTHESIS AND CELLULAR RESPIRATION

CHAPTER 8 & 9

ENERGY & ATP•Compounds that store energy:*ATP *NADH*NADPH *FADH2

–ATP•chief energy storing molecule; composed of:–adenine–Phosphates–Ribose (5 carbon sugar)

High energy bonds

•ATP does three types of work:–mechanical functions for cell

–active transport for movement of molecules across membrane

–breakdown and synthesis of large molecules

•ATP releases energy when a bond between 2 phosphates (P) is broken–Becomes ADP + phosphate

A – P ~ P ~ P A – P ~ P +P + energy

(releasing P & energy)

•ATP can be regenerated by bonding a phosphate back to ADP

SOURCES OF ENERGY

•Autotrophs -- organisms that make food from carbon dioxide and energy like sunlight; organisms that make their own food

•Heterotrophs -- organisms that depend on autotrophs or other heterotrophs for food; organisms that cannot make their own food

PHOTOSYNTHESIS•Energy from sunlight

–Introduction to Photosynthesis•Process in which autotrophs convert light energy into chemical bond energy of carbohydrates (sugar and starch)

–Pigment -- molecule that absorbs certain wavelengths of light•chlorophyll -- absorbs violet, blue, and red light

Reflected wavelengths determine what color you perceive an object to be;Absorbed wavelengths provide energy for photosynthesis

History–Van Helmont’s studies of mass accounted for contribution of water to plant growth.

–Priestley’s “candle” experiments showed oxygen needed for burning and that plants produced oxygen.

• Ingenhousz – effect shown by Priestley only occurs when the plant is exposed to light

•Conclusion of all 3: –in light, plants transform CO2 and water into carbohydrates and oxygen

•Chloroplasts–organelle that performs photosynthesis•thylakoid •grana

LEAFPLANT CELLS

CHLOROPLAST

•Thylakoid - sacs of membrane, chlorophyll containing structure in the chloroplast

•Grana - stacks of thylakoid, light collecting photosystems

•Stroma - gel-like material

stroma

thylakoid

grana

Chloroplast

Overview of Photosynthesis 6CO2 + 6 H2O ---------> C6H12O6 + 6O2

–Occurs in the chloroplast

–Produces glucose

-Requires light energy to start–Uses ATP & NADPH–Divided into 2 main parts

•Light Dependent Reactions

•Light Independent Reactions (Calvin Cycle)

•Light Dependent Reactions–first stage of photosynthesis requires light and water

–Takes place on thylakoid membrane•water is split

•O2 is released

•Electrons are harvested and used to make ATP and NADPH

•Light-Independent Reactions or The Calvin Cycle–Takes place in the stroma–requires the products of the light-dependent reactions

–CO2 is used to build carbohydrates (glucose)

Cellular Respiration

•Energy-Yielding Processes in Cells–Involves Breaking Down Food

–Series of Chemical Reactions that Produce ATP

Two Main Types:

•Cellular Respiration•Fermentation

•Cellular Respiration–process by which glucose molecules are broken down to release energy

C6H12O6 + O2 6CO2 + 6H2O + ATP(Energy)

–Fats, carbohydrates, and proteins may be broken down

•Cellular Respiration (continued)–requires oxygen; aerobic process

–produces 36 ATP molecules for each glucose molecule

–reverse equation of photosynthesis

•Overall Chemical Reaction Glucose + Oxygen -->Carbon dioxide + Water +

Energy (ATP & Heat)

C6H12O6 + 6O2 -----> 6CO2 + 6H2O + Energy (ATP

& Heat)

•Complete Cellular Respiration has Three Parts:–Glycolysis–Krebs Cycle–Electron Transport Chain

•Glycolysis–process by which glucose is converted to pyruvate and energy is released

–occurs in the cytoplasm

During the process, glucose yields 2ATP and pyruvates

Krebs Cycle–Pyruvates used–Occurs in mitochondria

–two ATP formed for each glucose

Electron Transport

•Energy from Krebs powers ETC

•requires oxygen•occurs in the mitochondria (powerhouse)

•produces 32 molecules of ATP

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Fermentation–extraction of energy from food

–does not require oxygen

–includes steps of glycolysis

–produces 2 ATP molecules

Fermentation (continued)

•two important types include

• Alcoholic Fermentation

•Lactic Acid Fermentation

•Alcoholic Fermentation•pyruvate converted to ethanol and carbon dioxide

•carried out by yeast and bacteria

•Lactic Acid Fermentation–pyruvate converted to lactic acid

–carried out by fungi and bacteria in making cheese and yogurt

•carried out by animals in muscle cells during early stages of strenuous exercise (blood cannot supply oxygen fast enough) – makes your muscles sore!

Anaerobic Respiration

•Some organisms do not ever use oxygen in the process of respiration –use sulfur, nitrogen, or carbon

Energy Flow in the Biosphere

•Making Food–most photosynthetic organisms produce more sugars than they need

•animals eat photosynthetic and heterotrophic organisms

•when plants or animals die, their energy stores are released to the environment