2.5 Cell Membranes

Question 1

What is the fluid mosaic model?

Answer 1

Theory of cell membrane structure with proteins embedded in sea of phospholipids

Question 2

Glycolipid

Answer 2

Lipid/phospholipid with a chain of carbohydrate molecules

Question 3

Glycoprotein

Answer 3

Protein with a chain of carbohydrate molecules attached

Question 4

Plasma membrane

Answer 4

Cell surface membrane

Question 5

What are the three types of protein in the cell membrane?

Answer 5

Protein channels
Protein carriers
Signalling proteins

Question 6

Who invented the mosaic model? And when?

Answer 6

Singer and Nicolson, 1972

Question 7

In neurones ( nerve cells ) what composition does the cell membrane have

Answer 7

-

Question 8

What is diffusion?

Answer 8

Movement of molecules from an area of high concentration to an area of low concentration; it may or may not be across a membrane; doesn’t involve metabolic energy (ATP)

Question 9

What is facilitated diffusion?

Answer 9

Movement of molecules from an area of high concentration of that molecule to an area of low concentration, across a partially permeable membrane via protein channels or carriers; does not involve metabolic energy (ATP)

Question 10

Factors that affect the rate of simple diffusion?

Answer 10

-Temperature (higher temp the quicker rate of diffusion)
-Diffusion distance( the thicker the membrane the slower rate of diffusion)
-Surface area( more diffusion can take place across a larger surface area)
-Size of diffusing molecule (smaller ions/molecules will diffuse more rapidly)
-Concentration gradient ( the steeper the gradient, the faster the rate of diffusioon?

Question 11

Example of diffusion

Answer 11

Carbon dioxide diffusing into the palisade mesophyll cells of a plant leaf will then diffuse into chloroplast to be used for photosynthesis