1. Diffusion and osmosis
7th grade Life Science

2. Intro to macromolecules
Carbohydrates, lipids, proteins and nucleic acids

3. Macromolecules macro = big
Carbohydrates
lipids
Organic molecules
Supply energy for the cell (break down)
Simple (table sugar) and complex carbs (pasta or starch)
Examples: sugars, starches and fibers
Organic molecules
Store energy in cell (even more energy than carbs)
major part of cell membrane
Do not mix with water
Examples: fats and oils

4. Macromolecules macro = big
proteins
Nucleic acids
Organic molecules
Made of smaller molecules called amino acids
Used to build and repair many structures
Enzymes and scattered in cell membrane
Found in eggs, milk, peanut butter, meats and beans
Large organic molecules
Store important coded info in cells
Dna (deoxyribonucleic acid) – genetic material in cells
Rna (ribonucleic acid) – needed to make proteins, such as enzymes

5. To maintain homeostasis, cells must: - exchange materials
Homeostasis stability – keep a constant internal state in a changing environment
To maintain homeostasis, cells must: - exchange materials
- eliminate waste
- obtain and use energy
- make new cells

6. Exchange of materials for the cell
Cell membranes are semipermeable – only certain particles can move in or out of cell (selective)
Passive transport: transport of materials straight through the cell membrane (does not use energy)
Active transport: transport of materials through protein channels in cell membrane (requires energy)
Protein channel
energy

7. Diffusion and osmosis (passive transport)
Movement of molecules from high concentration to low concentration
Movement of water through a semipermeable membrane from areas of higher to lower concentration

8. In Which direction will the particles move or diffuse?

9. Answer: The particles diffuse from more concentrated to less concentrated!

10. In Which direction will the water move? (osmosis)

11. Answer: The water moves from less concentrate to more concentrate!

12. DIFFUSION and osmosis
Concentration gradient: uneven distribution of a substance across a border
Solute: particles dissolved in water
SOLUTION: MIXTURE OF WATER AND SOLUTE
Isotonic: Equilibrium, same concentration in 2 different areas
Hypertonic: the area with higher concentration of solute (less water)
Hypotonic: the area with lower concentration of solute (more water)

13. water Essential for cells
Water moves across the cell membrane by osmosis
it depends on the concentration of water inside and outside the cell

14. Vesicle transport exocytosis Endocytosis
Process in which particles are enclosed in a vesicle in the cell and then released from the cell
Opposite of endocytosis
Exo = out
Process in which cells surround and enclose a particle in a vesicle to bring it into the cell
It requires energy
Endo = in
ENDO
EXO

15. Diffusion lab Groups: A) Warm water x 2 B) cold water x 2
C) room temperature water x 2
d) room temp water with stirring x 2

16. Instructions Group d only: stir! 
Identify people in your group and what group you are in (a, b, c, or D) on your worksheet
Add 200 mL of water in your beaker, according to what your group needs (warm - a, cold - b, or room temperature – c and d)
Add 1 drop of food coloring in your water – start the timer
Group d only: stir! 
Stop timer when the food coloring has spread out evenly in the water
Write down how long it took for food coloring to be evenly distributed
ENTER YOUR INFO ON TABLE AT FRONT

17. Carrot lab
experiments:
1 – fresh water
2 – salt water

18. Why do you predict this? Give some rationale!
instructions
Identify people in your group
with your group, write a prediction of what is going to happen to the carrot stick in experiments 1 and 2, add an explanation
PREDICT:
1. What will happen to a carrot stick that soaks in fresh water overnight? (texture, shape, or other characteristics)
2. What will happen to carrot sticks that soak in salt water overnight?
EXPLAIN:
Why do you predict this? Give some rationale!
OBSERVE:
TOMORROW

19. Bellringer 12/3/15 - answers
Too much water enters the cell cell gets swollen, maybe bursts
Too much water leaves the cell cell gets shriveled (dehydrated)
2) diffusion; particles will move from area of high
concentration to low concentration

20. Diffusion lab part 2 Which particles will diffuse:
iodine, starch or both?
Important information: iodine is an “indicator”
* it changes color when it encounters starch *

21. Bellringer 12/4/15 - answers
1) Isotonic more concentrated (more particles, less water)
Hypertonic less concentrated (less particles, more water)
hypotonic same concentration, equilibrium
2) Cell membrane encloses particles to bring them into the cell
3) Cell membrane encloses particles from the inside of the cell to release them to the outside