Cellular Respiration

C 6

-

the breaking down of food molecules in the presence of oxygen

to release energy

H 12 O 6 (glucose) + O 2 CO 2 + H 2 O +

ATP

(energy)

Metabolism • • • The set of chemical reactions in an organism’s cells that converts food into energy (ATP) “Burning calories” refers to how efficiently cells can perform cellular respiration More exercise = more energy required = QuickTime™ and a TIFF (Uncomp resse d) de com press or are nee ded to s ee this picture.

more food required = faster metabolic rate

What is ATP?

• • • Molecule that is used as an energy source in the cell Produced in mitochondria Food molecules are needed to make ATP QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

ATP

Adenine Ribose P P P

3 Phosphate groups

Adenine

ATP

ENERGY

stored in bonds

P P P

3 Phosphate groups

Ribose

A D P ATP

P P

ENERGY RELEASED

3 Steps of Cellular Respiration (each produces some ATP) 1) 2) 3) Glycolysis

- splitting of glucose (2 ATP) (

anaerobic

- no O 2 needed

Citric Acid (Kreb’s) cycle

) (2 ATP) (

aerobic

- O 2 needed )

Electron transport chain

(32-34 ATP) (

aerobic

) *steps 2 and 3 happen in mitochondria *step 1 happens in the cytoplasm outside the mitochondria

What happens without oxygen?

• Citric acid cycle and electron transport chain (ETC) cannot occur • • Glycolysis is followed by

fermentation

There are two types of fermentation:

alcoholic

and

lactic acid

See diagram

O 2

Glucose

Is split apart in

Citric acid cycle and Electron transport chain

Glycolysis

No O 2

Alcoholic Fermentation • Happens in microorganisms (yeast and bacteria) in the absence of oxygen ( anaerobic ) • • Alcohol and CO 2 are produced Does not produce ATP, but it does allow glycolysis to occur again and again • Used in the beer and wine industry

Lactic Acid Fermentation • Happens in muscle tissue of humans and other animals in the absence of oxygen ( anaerobic ) • • Lactic acid and CO 2 are produced Does not produce ATP, but it does allow glycolysis to occur again and again • Produces burning feeling during exercise

When oxygen is present… • • • • • Kreb’s cycle (citric acid cycle) and electron transport chain occur Both happen inside the mitochondria 2 ATP come from the Kreb’s cycle 32-34 ATP come from the electron transport chain Total of 36-38 ATP from cellular respiration (includes 2 ATP from glycolysis) * ATP amounts shown are produced from ONE glucose molecule

Aerobic vs. Anaerobic • • • •

Anaerobic Respiration

Energy produced quickly No oxygen needed Glycolysis and fermentation Few ATP produced • • • •

Aerobic Respiration

Energy produced more slowly Oxygen needed Citric acid cycle and ETC More ATP are produced per molecule of glucose

What is Photosynthesis?

The process of using sunlight to convert CO 2 and water into glucose and oxygen

QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

CO 2 + H 2 O C 6 H 12 O 6 + O 2 Reaction takes place in the chloroplast

Converting Solar Energy • • • Plants trap the sun’s energy using a green pigment called

chlorophyll

Chlorophyll is inside the chloroplast Solar energy is used to transform CO glucose 2 into QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Factors that Affect Photosynthesis

• •

Water availability Light intensity (varies from species to species)

•

Temperature (extremes slow down photosynthesis - below 0 o C and above 35 o C)

Photosynthesis is divided into two processes:

Overview of Light Dependent Reactions

• • •

Require light to occur Produce oxygen gas Produce ATP

The Calvin Cycle

Uses energy stored in ATP to produce glucose from CO 2 .

* Six CO 2 molecules from the atmosphere are needed to produce one glucose molecule

Summary of the Reactions of Photosynthesis

What is the glucose used for?

• Energy source for plant and consumers • To build starches (stored food source) • To build new cell walls

CO 2 Cellular Respiration (from cell respiration) vs. Photosynthesis O 2 + carbohydrates (from photosynthesis)