1. Key Idea #11
Cells in multicellular organisms are specialized to take in nutrients, which are used to make the materials that a cell or organism needs.

2. Nutrients taken in by the cell provide materials to build
cell structures (organelles) and
specialized molecules used by the organisms:
carbohydrates
lipids (fats)
proteins
nucleic acids: DNA and RNA

3. Organic and Inorganic Compounds
contain carbon
include carbohydrates, proteins, lipids, and nucleic acids
Inorganic Compounds
do not contain carbon*
includes water, sodium chloride (table salt) and carbon dioxide* - an exception

4. Carbon dioxide and water are used to produce carbohydrates, proteins and fats (lipids).

5. Carbohydrates
are energy-rich compounds made of the elements carbon, hydrogen, and oxygen
are an important part of cell membranes and cell walls
include sugars
fruits and some vegetables
include starches
potatoes, noodles, rice, and bread contain starch that your body breaks down into glucose (a sugar)

6. Proteins
are large organic molecules make of carbon, hydrogen, oxygen, nitrogen and sulfur.
are found in foods such as meats, eggs, fish, nuts and beans
form parts of cell membranes
make up many of the organelles found in cell
are used by cells in your body to build body parts such as hair.

7. Lipids are energy-rich compounds made of carbon, hydrogen, and oxygen.
include fats, oils, and waxes.
includes cholesterol
an important part of animal cell membranes
Meat, cheese, and eggs are all high in cholesterol

8. Nucleic Acids
are very large organic molecules made of carbon, oxygen, hydrogen, nitrogen, and phosphorus.
contain the instructions needed to carry out life.
DNA
genetic material that contains the information that is passed from parent to offspring
RNA
important for protein production
found in the cytoplasm and nucleus

9. Water must be present for most chemical reactions to take place.
helps cells keep their size and shape

10. Diffusion and Osmosis

11. Cell Membrane acts as a gatekeeper is selectively permeable
controls what substances can enter or leave the cell
is permeable to oxygen, water, and carbon dioxide to pass through it
is not permeable to some large molecules and salts

12. Substances that can move into and out of a cell use one of three methods:
Diffusion
Osmosis
Active Transport

13. Diffusion – Molecules in Motion
Diffusion is the main method by which small molecules move from an area of higher concentration to an area of lower concentration.

14. What causes diffusion?
Molecules bump into each other and eventually spread out evenly throughout an area.
Example: Air freshener spreads out when you spray it.

15. When there is a higher concentration of molecules outside a cell than inside a cell
the molecules diffuse (move) into the cell until there is an equal number of molecules inside and outside the cell.
These molecules can be oxygen, carbon dioxide or water

16. When the molecules are equal on both sides of the cell membrane, it is called equilibrium.
Googleimages.com

17. Osmosis is a type of diffusion.
is the diffusion of water molecules through a selectively permeable membrane.
is important to cells because they can’t function properly without adequate water.
Note: Only water molecules pass through the membrane during osmosis

18. occurs when water molecules move from an area of higher water concentration to an area of lower water concentration until equilibrium is reached.
Note: other dissolved particles can’t pass through the membrane

19. FYI: A simple rule to remember is:
                               
When salt is concentrated inside or outside the cell membrane, it will draw the water in its direction.
This is why
you get thirsty after eating something salty because the excess salt draws water to the cells in the body.
people lost at sea will speed up dehydration (and their death) by drinking sea water.
“salting fields" was a common tactic used during wars to cause food shortages.

20. Osmosis & different concentrations of solute:

21. In normal cells:
the amount of dissolved salt molecules is equal on both sides of the cell membrane.
the water moves back and forth but the overall amount of water on either side remains the same.

22. When there are more dissolved salt molecules inside the cell than outside the cell:
water moves into the cell since “salt sucks”.
the cell grows larger.

23. In plant cells this causes
the central vacuoles to fill with water and the plant becomes rigid.
Note: The cell wall keeps the plant from bursting.

24. In animal cells the cells may be in danger of bursting.
contractile vacuoles pump water out of the cell to prevent this.
Googleimages.com

25. When there are more salt molecules outside the cell than inside the cell
the water is sucked outside the cell.
the cell shrinks.

26. In plant cells, the central vacuole loses water and the cells shrink, causing wilting.
In animal cells, the cells also shrink and shrivel up.
In both cases, the cell may die.

27. FYI: Why can’t fish live in both fresh and salt water?
Salt water fish
have cells that don’t contain as much salt as the salt water they live in
cells lose a lot of water into the water around them by osmosis
must drink a lot of water and produce little urine to compensate
Fresh water fish
have cells that contain more salt than the fresh water they live in
cells gain water from their surroundings by osmosis
don’t usually drink water and produce large amounts of urine to compensate

28. Substances move in and out of cells by
passive transport
no energy is needed
diffusion
osmosis
active transport
cell uses energy (ATP)
engulfing
contraction of vacuole wall eliminates waste
transport proteins in the cell membrane pick up molecules outside the cell and carry them in

29. Nutrients that can’t pass through the cell membrane by diffusion can be taken into the cell through active transport.
Active transport uses the cells energy to accomplish this.

30. Active Transport

31. Active transport examples:
engulfing
transport proteins in the cell membrane pick up molecules outside the cell and carry them in
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