1. Biology Notes Cells Part 2 Pages 81-91

2. Standard Essential Question:
2.6
____ Explain the role of cell membranes as a highly selective barrier (passive and active transport)
Essential Question: 1.
How do materials enter and leave cells?

3. I. Cell Communication & Cell Membranes
Cells must communicate with each other in order to keep an organism in ____________ Homeostasis = regulation of an organism’s ________ environment in order to maintain balance e.g.
homeostasis
internal
pH, body temperature, heart rate, etc.

4. Cells send messages to other cells about what they _____ and what they need to get rid of in order to keep this homeostasis
messages can be sent between cells that are _________ or _________
need
chemical
electrical

5. Cell Membrane = the organelle that surrounds cells to provide ________ and protection as well as to regulate what _______ and______ the cell
support
enters
exits
a.k.a. – plasma membrane

6. The cell membrane plays a vital role in cell communication by regulating what messages can ______ and ____ the cell
The cell membrane also plays a vital role in homeostasis by regulating what molecules can ______ and ____ the cell
e.g.
selective permeability = the ability of the cell ___________ to allow some materials to ______ into a cell while keeping others out
enter
exit
enter
exit
in = H2O, food out = waste, CO2
membrane
enter

7. II. Cell Membrane Structure
Protein-lipid bilayer = a strong double layer of _____ containing embedded ________ make up the majority of the cell membrane structure
Also called the _____ mosaic model
lipids
proteins
fluid
Why would the cell membrane be made out of lipids???
- It needs to be waterproof

9. The lipids are called ______________ because each one has a __________ molecule attached
The lipid heads are not ________ whereas the tails are ________
phospholipids
phosphate
soluble
soluble
lipid heads = hydrophilic &
polar
lipid tails = hydrophobic &
non-polar

11. The embedded ________ carry out most of the functions of the plasma membrane
- some proteins serve as _________ and destroy any material that could ______ the cells
- cholesterol serves to ____________ the cell
membrane
other proteins have ______________ attached that serve as a “beacon” for materials needed ______ the cell
proteins
enzymes
harm
strengthen
carbohydrates
inside

12. DIAGRAM:

13. III. Cell Membrane Action
In order to maintain ____________, the concentration of most substances in and out of the cell must be _________
Concentration = in a ________, the amount of ______ in a given volume of _______ (mass / _______)
e.g. What is the concentration of salt if there are 12 grams of salt in 3 liters of water?
homeostasis
balanced
solution
solute
solvent
volume
4g/L

14. Concentration gradient = the difference in _____________ across a space
If the concentration of substances are not ______ in and out of cells, then the cell membrane may take _______ to balance the concentrations
there may be exceptions to this rule
e.g.
concentration
equal
actions
food always in / CO2 always out

15. A. Diffusion = the net movement of particles from an area of _____ concentration to an area of ____ concentration until dynamic equilibrium is reached
Substances are said to be moving ______ their concentration _________
Dynamic equilibrium = when the concentration of particles are ______ both inside and outside of the ____
Diffusion requires no _______
high
low
down
gradients
equal
cell
energy

16. DIAGRAM:

17. Diffusion will only occur with small molecules like _____, ____, _____ and ___. Other larger molecules, like ________________, cannot use _________ to enter or exit a cell.
CO2
H2O
NH3 O2
glucose (C6H12O6)
diffusion

18. B. Osmosis = the diffusion of ______ from an area of _____ concentration to an area of low _____________ through a selectively permeable ___________
requires no _______ because it is _________
occurs in solutions when the solute is too ______ to pass through the membrane so the water will move until the concentrations on either side of the membrane are ______
water
high
concentration
membrane
energy
diffusion
large
equal

19. Why is this picture wrong?

21. Isotonic solution = a solution in which the concentration of ________ is the same on both sides of the _____
there is no net movement of ______
DIAGRAM:
solution
cell
water

22. Hypotonic solution = a solution in which the concentration of ________ is lower ________ the cell than ______ the cell
water will move ____ the cell
and the cell will appear
________
osmotic pressure =
pressure created inside
the cell when water moves ___
solution
outside
inside
into
swollen in

23. DIAGRAM:

24. Hypertonic solution = a solution in which the concentration of ________ is higher ________ the cell than ______ the cell
water will ______ the cell a
and the cell will appear
_______
plasmolysis = the drop of ________ pressure inside a cell when water _______ the cell
solution
outside
inside
leave
wilted
osmotic
leaves

25. DIAGRAM:

29. C. Facilitated Diffusion = movement of materials across a ____ membrane by means of _________ proteins
allows ______ molecules like ________ to cross
does not require _______
molecules still move ______ their concentration gradient
cell
transport
a.k.a. passive transport
larger
C6H12O6
energy
down

31. DIAGRAM:

32. D. Active Transport = the movement of materials across a ____ membrane when it is ________ their concentration gradient
requires _______ to move materials from ____ to high concentration
DIAGRAM:
cell
against
energy
low

35. E. Endocytosis = a process of taking material ____ the cell by means of _______ the entire cell membrane 1. phagocytosis = a type of endocytosis in which extension of the __________ surrounds a particle and packages it within a food ________ e.g.
into
moving
membrane
vacuole
How amoebas intake food.

38. 2. pinocytosis = a process by which cells take in _______ from the surrounding environment by forming ________ along the cell ___________ F. Exocytosis = a process by which material is _________ from a cell by ______ with the cell membrane e.g.
liquids
pockets
membrane
excreted
fusion
lysosomes

40. IV. Everyday Cell Membrane
Food Preservation
Adding ____ to make food last longer
creates a ___________ solution so that water moves out of the _____
prevents food from ________ by killing any ________
Works through _________
salt
hypertonic
cell
spoiling
bacteria
osmosis

42. B. Kidneys

43. The nephron filters the ______ as it moves through the kidneys
substances like ___, ____ and waste or excess ____ are removed and sent for _________
e.g.
Substances are removed by _________, __________________ and active _________
blood N2
NH3
H2O
excretion
urine in bladder
osmosis
facilitated diffusion
transport

47. C. Lungs

48. The alveoli exchanges _____ for ___ through simple _________
CO2 O2
diffusion