8.1 How Organisms Obtain Energy 2014

Metabolism Overview

1. 8.1 How Do Organisms Obtain Energy?

2. 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

3. Thermodynamics
1st Law = energy can be converted
from one form to another, but it
cannot be created nor destroyed.

4. Thermodynamics
2nd Law = energy cannot be
converted without the loss of
useable energy
–Usually lost as heat
–Disorder (entropy) increases

5. Entropy

6. 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!

7. 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.

8. ATP
“Energy Currency” –
It is like money
that can be
spent throughout
the cell!

9. How is ATP constructed?
Adenosine triphosphate: is made of
•Adenine
•Ribose sugar
•3 phosphates
Adenosine diphosphate:
•remove 1 phosphate,
you have ADP

10. 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

12. 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

13. 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