1. Cell Membrane

2. Functions of Cell Membrane
communication via cell receptors
transport, controls what enters and leaves the cell
encloses all other organelles
CANNOT keep harmful substances out of cell

3. Cell Receptors
Notes from background reading of cell receptor activity

4. Cell Receptors are in cell membrane attach to specific chemicals
receives message from those chemicals
specific, like enzymes
are proteins

5. Examples of messengers
from background reading of cell receptor activity

6. Examples of messengers
hormones
bee venom
pollen
viruses like HIV
steroids
fertility drugs

7. Cell Receptors Receptor must fit with hormone or other chemical
Receptor receives message from messenger like hormone
Receptors are specific because of their shape.

8. Perform activity

9. Target cells
Hormones are produced in one area of the body and are transported by the bloodstream to the target cell.

10. Cell Receptors Cell A is the target cell for the circular messenger.
Cell B is the target cell for the triangular messenger.
receptor
messenger

11. Structure of Cell Membrane
Fluid Mosaic Model
lipids
proteins
Pearsonsuccessnet
Activity 6.2

12. Cell Membrane - Cheek Cell
cell membrane - lipid bilayer

13. Cell Membrane - micrograph
lipid bilayer seen through electron microscope

14. Types of Membrane Transport
Passive transport
molecules move from high concentration to low concentration
occurs because of a concentration gradient, no energy required

15. Types of Membrane Transport
Active transport
molecules move from low concentration to high concentration
requires energy in the form of ATP

16. Examples of passive transport
diffusion, osmosis
Where occurs
Lungs, oxygen diffuses from lungs to blood
Lungs, carbon dioxide diffuses from blood to lungs
Small intestine, nutrients diffuse into blood
diffusion animation
gas exchange animation

17. Diffusion in the Digestive System
equilbrium
high concentration
low concentration

18. Diffusion in the Respiratory System
oxygen diffuses from lungs into bloodstream
carbon dioxide diffuses from blood into lungs

19. Diffusion into body cells
oxygen diffuses from blood into cells
carbon dioxide diffuses from cells into blood

20. represents cell membrane
Diffusion
dotted line
represents cell membrane

21. Diffusion
permeable to small molecules, not permeable to large molecules

22. Diffusion Size of the molecule determines if it can cross the membrane
Cell membrane is semi-permeable
Net result of diffusion is equilibrium

23. Size of molecules PearsonSuccessnet Activity 6.3 big molecules
small molecules
sugars, ex. glucose
amino acids
fatty acids
nucleotides
oxygen, water, carbon dioxide
carbs, ex. starch
proteins
lipids
nucleic acids

24. Osmosis
diffusion of water

25. Osmosis in a red blood cell
in distilled water (100% water)
in blood plasma H
water diffuses into cell L
equal concentration inside and outside of cell

26. Transport in and out of cells
Water diffusing in cell
Water diffusing out of cell

27. Water concentrations Tap water around 95% water
Distilled water is 100% water (always considered high concentration)
Cytoplasm is around 75% water
Salt water is from 85%-94% water (always considered low concentration)

28. Osmosis in a Paramecium
Water is pumped out of the paramecium.
Active transport: low to high conc., using ATP
75% water in cytoplasm
99% water
Water moves into the cell by osmosis.
paramecium video

29. Plasmolysis
Shrinkage of the cell membrane and cytoplasm due to water loss
Water leaves the cell by osmosis

30. Elodea cell in distilled water
water moves into cell by osmosis

31. Elodea cell in salt water
water moves out of cell by osmosis

32. Elodea cell
cell wall
cell membrane
chloroplasts
400x
cytoplasm

33. Plasmolyzed elodea cell
elodea video
cell wall
cell membrane
chloroplasts
cytoplasm
400x

34. Types of Transport Passive
movement of molecules from high concentration to low concentration
no energy used
molecules move because of a difference in concentration - a concentration gradient

35. Examples
Diffusion and osmosis

36. Types of Transport Active Transport Examples
movement of molecules from low
concentration to high concentration
energy is needed
Examples
paramecium pumping water out of cell