Unit 2 Section 3

Energy Use

• Energy is essential to life.

• All living organisms must be able to obtain energy from the environment in which they live.

• Organisms can be classified according to the origin of their energy.

A.Autotrophs - organisms that make their energy, via photosynthesis; All life depends on autotrophs. AKA: Producers

B. Heterotrophs - organisms that must consume their energy by eating autotrophs and/or other heterotrophs. AKA: Consumers

I. CELLS CHEMICAL ENERGY

ATP - (adenosine triphosphate) Cells

energy molecule that can be used

easily and quickly. - ATP molecule has two parts: adenosine

(adenine + ribose) and phosphate groups

Energy is found in the bonds between the

phosphate groups

II. Photosynthesis

• Definition: Converts solar energy (radiant, light) into chemical energy stored as carbohydrates (sugars).

• Who: Autotrophic organisms

• Where: Chloroplast of plant cells.

internal leaf structure

chloroplastsouter membrane

inner membrane

thylakoid

• Reactants: Carbon Dioxide, water and

Sunlight

• Products: Carbohydrates (sugar) and

Oxygen

• Equation:

6 CO2+ 6 H2O + light energy C6H12O6 +6 O2

A. Chloroplast

• Organelle of plant cells• Function: Site of

photosynthesis• Chlorophyll – pigment Chlorophyll – pigment

found in chloroplast that found in chloroplast that traps sunlight and gives traps sunlight and gives plants their green color.plants their green color.

B. Gas Exchange

• Stomata – Pore of the leaf where gas exchange takes place (CO2 and O2)

• Closes to conserve water and opens to release water

Photosynthesis Summary

The plant absorbs carbon dioxide from the atmosphere, draws water up through its roots and uses light to photosynthesize sugars,which it uses as food. It also excretes oxygen as a by-product of the process.

III. Cellular Respiration

• Definition: Process of synthesizing

ATP by breaking down carbohydrates (organic compounds)

• Where: Mitochondria

• Reactants: Carbohydrates (sugars) and Oxygen

• Products: Carbon Dioxide, Water and

ATP

• Equation: C6H12O6 + 6 O2 6 CO2+ 6 H2O + ATP

Cellular Respiration

• Types:

1. Aerobic – means with oxygen – normal type of respiration that has already been described.

2. Anaerobic – means without oxygen – special type of respiration

when the oxygen supply is absent.

COMPARISON Aerobic

Respiration

Anaerobic

Respiration

Reactants Oxygen and Carbohydrates

Carbohydrates

ATP Large Amounts36 total

Small Amounts2 total

Types Alcoholic Fermentaion – Bacteria / Fungi

Lactic Acid Fermentaion – Animal Cells

Produces ATP and Carbon Dioxide

Alcohol or Lactic Acid, ATP and Carbon Dioxide

IV. Biochemical Pathways• A complex series of chemical reactions, in

which the product of one reaction is consumed in the next reaction.

• Example:

Photosynthesis

Cellular Respiration

6 CO2+ 6 H2O + light energy C6H12O6 + 6 O2

C6H12O6 + 6O2 6 CO2 + 6 H2O + ATP

What are we missing?

V. ATP-ADP CYCLE

• Definition: Process where energy is released from the bonds of an ATP molecule for the cells activities.

• Where: Mitochondria

• How: It works by breaking off ATP’s phosphate groups which releases energy.

• Reactant: ATP

• Product: ADP (Adenosine Diphosphate) and usable ENERGY!!!!

Adenine

P P P

High-Energy Bond

Although we classify organisms according to their food energy, in an indirect way all organisms get their energy from light. Why and How?

VI. Energy Pathway - Putting it all together -

• Autotrophs:

Sun Plants Chloroplast (Photosynthesis) Carbohydrates Mitochondria (Cellular Respiration) ATP ATP-ADP Cycle (Mitochondria) USABLE ENERGY IS MADE FOR CELLS ACTIVITIES!!!!!!

VI. Energy Pathway - Putting it all together -

• Heterotrophs:

Sun Plants Chloroplast (Photosynthesis) Carbohydrates Heterotroph eats Autotroph (Digestion) Carbohydrates Mitochondria (Cellular Respiration) ATP ATP-ADP Cycle (Mitochondria) USABLE ENERGY IS MADE FOR CELLS ACTIVITIES!!!!!!