8.1 How Do Organisms Obtain Energy?

Many chemical reactions and processes are going on in your body even when you are not aware of it!–These cellular activities require

ENERGY!

Energy

Energy = the ability to do work

Thermodynamics1st Law = energy can be converted

from one form to another, but it cannot be created nor destroyed.

Thermodynamics

2nd Law = energy cannot be converted without the loss of useable energy

–Usually lost as heat

–Disorder (entropy) increases

Entropy

All organisms need energy to live Autotrophs =

organisms that make their own food

– Example: Plants

Heterotroph = organisms that ingest food to obtain energy- Example: You!

How do cells release energy? Energy stored in food molecules is

released in a series of enzyme-catalyzed chemical reactions.

When cells break down molecules, some of the energy released is in the form of heat.

The rest of the energy is stored as ATP.

ATP“Energy Currency” –

It is like money

that can be

spent throughout

the cell!

How is ATP constructed?

Adenosine triphosphate: is made of• Adenine• Ribose sugar• 3 phosphates

Adenosine diphosphate:• remove 1 phosphate,

you have ADP

ATP ADP + P

When one phosphate breaks off the energy is RELEASED

When one phosphate is added the energy is STORED in the phosphate-phosphate bond

Cellular Respiration Series of reactions that break down

organic molecules into carbon dioxide, water and creates ATP

Photosynthesis Series of reactions that change light

energy from the sun into chemical energy to be used by the cell

Metabolism: all of the chemical reactions in a cell

Two Metabolic Pathways:

Catabolic: the breakdown of nutrient molecules into useable forms - “count them down”

example = Cellular Respiration

Anabolic: build new molecules from the products of catabolic pathways

“add them up” example = Photosynthesis