1. Water and Life Processes
Biology

2. Water ¾ of your body is water Water is essential for survival.
Water can dissolve many substances
It serves as a vehicle to carry gases, nutrients, and waste through organisms.
Water is involved in all body processes.

3. Water
The region where the oxygen atom is located is slightly negative.
The region where the hydrogen atoms is located is slightly positive.
This uneven pattern of charge is called polar.
Water’s polarity makes it a useful solvent.

4. Water
Water dissolves other polar substances like sugar, some proteins, and some ionic compounds (like table salt).
When an ionic compound is dissolved in water, it breaks up into charged particle called ions.

5. Homeostasis
The ability of a cell or organism to regulate its internal conditions despite changes to the environment.
Water is an important factor in the regulation of body temperature, which maintains homeostasis.

6. Diffusion
Cells must be able to take in nutrients to carry out life functions.
One way is through diffusion.
Diffusion is the movement of particles from an area of high concentration to an area of low concentration.

7. Passive Transport
The movement of materials into or out of the cell without the expense of energy.
Diffusion is an example of passive transport.
Facilitated diffusion is using protein channels embedded in cell membrane help specific molecules pass through more easily than others. (passive transport)
Ex: Glucose into red blood cells

8. Osmosis
Water molecules moving from a place of high concentration to a place of low concentration.
This is also passive transport.
Water is probably the most important substance that passes through the cell membrane.
Concentration gradient is the difference in concentration that makes osmosis possible

9. Hypertonic vs. Hypotonic Solutions
Hypertonic solution = concentration of solute outside of the cell is higher compared to that in the cytoplasm inside the cell.
Cells shrink inside hypertonic solutions.
Hypotonic solution= The concentration of solute outside the cytoplasm is lower compared with that outside the cell.
Cells placed in hypotonic solution will grow/swell and maybe explode.

10. Isotonic
Solutions with equal concentrations on both sides of a membrane.
The cell should remain the same.
Equilibrium is when concentrations inside and outside the cell are equal.
Once equilibrium is reached, particles continue to diffuse across the cell membrane in both directions.

11. Active Transport Requires energy Can use the protein channels
Example: sodium-potassium pump—sodium ions are pumped out and potassium ions are pumped into the cell by specific channel proteins.

12. Endocytosis vs. Exocytosis
Endocytosis: The cell membrane forms a fold or pocket.
The pocket separates from the cell membrane and forms a vacuole in the cytoplasm of the cell.
The material is taken into the cell.
Exocytosis: The membrane of a vacuole in the cytoplasm of a cell can fuse with the cell membrane.
Any contents in the vacuole can be forced out of the cell.