1. Temperature can
affect the rate at
which chemical reactions
happen
Low temp = slow reactions
High temp faster reactions
Enzymes are special ‘helper’ proteins that help a chemical reaction to happen quicker

2. Macromolecules
Atoms come together to form macromolecules important to life
Macro = big
1. Proteins (single most important macromolecule for life)
2. Carbohydrates (energy)
3. Lipids (fats, oils, waxes)
4. Nucleic acids (DNA, RNA)

3. Water is also an important molecule but it is not made by the body
It is used in virtually every chemical reaction in our body
Water has an unusual structure called a polar molecule that allows for all these different types of reactions to happen
A polar molecule has one side that has a slight positive charge & one side that has a slight negative charge

4. The 7 Characteristics of Life
In order for an organism to be considered alive it MUST meet all 7 of the characteristics of life!!!
1. Cells & Organization
The cell is the smallest unit that can perform all life’s processes
One celled organisms are called unicellular (singlecelled)
- Organisms made up of two or more cells are called multicellular

5. 2. Response to their environment
A living organism can respond to a stimulus
A stimulus is a change in the organisms environment
Temperature, too much or not enough water, fertilizer, pollution...

6. 3. Maintain balance (homeostasis)
An organism must have a stable inside environment even when the outside environment is constantly changing
Ex. You shiver when it is cold to maintain body temperature
All living organisms must maintain balance in order to be healthy

7. 4. Metabolism
Metabolism is the process of using energy to power functions & growth
This energy is in the form of food or nutrients

8. 5. Growth & Development
All living things grow & increase in size
Development is the process by which an organism becomes a mature adult

9. 6. Reproduction
This is the process of producing a new organism that looks like the original
During reproduction, hereditary information is passed onto the next generation (DNA, RNA)

10. Sexual reproduction: when DNA from two different organisms combine to form a new organism
The offspring is similar to but not identical to the original organism
Asexual reproduction: when there is no comb ination of DNA from two organisms
The offspring is genetically identical to it’s parent

11. 7. Change through
time (Evolution)
Although individual
organisms experience many changes during their lifetime, their basic genetic characteristics do not change.
However, populations of organisms change through time (evolve)
This is important for the survival of species