1. Chapter 2 Section 2 –Necessities of Life

2. 4 Necessities of Life
Water (Most chemical reactions for “metabolism” – all organisms activities, including getting energy from food, growing. etc – requires water. May get from food.)
Air (Need for chemical process to get energy from food. Some organisms (anaerobic) do not need air; some types of bacteria are examples.)
Shelter (Actually means having a place to live with access to all needs.)
Food (Need to have energy and materials to carry out life processes.)

3. Competition
Organisms often have to compete for food, water, shelter or other necessities.

4. “Making” vs. “Taking” Food
Producers: Make their own (produce) food via
photosynthesis
Consumers: Must eat other (consume) organisms to get food
Types of Consumers: Herbivores (eat producers; ex: zebra)
Carnivores (eat consumers; ex: lion) Omnivores (eat both; ex: brown bear) Detritivores (eat dead organisms; ex: vulture) Decomposers (detritivores that break down complex molecules in dead tissue/ wastes into simpler molecules; ex: mushrooms)

5. Putting It All Together
All organisms need to breakdown food to get/use nutrients.
Nutrients are made of molecules (substance made of >2 atoms).
Organisms’ molecules mostly made from 6 elements: carbon / hydrogen / nitrogen / oxygen / phosphorus / sulfur
Elements combine to make: proteins/ carbohydrates / lipids / ATP / nucleic acids

6. Proteins Necessary for almost all life processes of cell
Made of amino acids (smaller molecules)
Many functions:
Some form structures (hair, spider webs)
Some help cells do jobs ( hemoglobin delivers oxygen thru body)
Some are enzymes (speed chemical reactions)
Needed to build and repair the body

7. Carbohydrates (Carbs)
Made of sugars
Provide and store energy
Simple Carbs
Made from 1 sugar or just a few sugar molecules
Examples: table sugars and fructose (sugar in fruit)
More common than complex carbs
Complex Carbs
Made from 100’s of sugar molecules which are linked
Example: potato starch

8. Lipids Molecules that cannot mix with water Have many jobs
Some store energy
Fats - animals
Oils – plants
Phospholipids
Make cell membranes
Pair up; “heads” attracted to water, and “tails” avoid water

9. ATP Molecules called Adenosine Triphosphate
Job: major energy carrying molecule of cells
Energy from carbs or lipids are transformed to ATP to provide fuel

10. Nucleic Acids Molecules that carry directions for how to make proteins
Made of smaller molecules called nucleotides
Sequence stores information
DNA is an example of a nucleic acid which directs making proteins

11. Additional Information
For additional information…especially chemistry…go to User name: minerva13 password: minerva Then visit the visual concepts for Ch 2 Section2