LEC 6

Question 1

Plasma membrane

Answer 1

cell membrane
phospholipid bilayer

Question 2

Plasma membrane components (3)

Answer 2

1. phospholipids
2. cholesterol
3. proteins

Question 3

Purpose of cholesterol in cell membrane

Answer 3

increases strength and rigidity

Question 4

Purpose of proteins in cell membrane

Answer 4

embedded in membrane
helps move materials in and out of the cell
communication b/w cells

Question 5

Receptor proteins def (2)

Answer 5

embedded in the plasma membrane
transmit information (to make something happen in the cell)

Question 6

How do receptor proteins work?

Answer 6

signaling molecule binds to receptor site and triggers a series of chem reactions

Question 7

Open Channel (2)

Answer 7

always open
allowing free movement in/out of the cell

Question 8

Gated channel (3)

Answer 8

Is closed
limits what can enter/leave the cell
“Right” material triggers or signals it to open

Question 9

Transport Protein (2)

Answer 9

Allows specific molecules to enter/leave the cell
Protein physically changes shape to transport the material

Question 10

Glycoprotein

Answer 10

Has specific carbohydrate groups attached to the surface
Used in cell-to-cell recognition and communication

Question 11

Membrane polar or non-polar?

Answer 11

polar

Question 12

Types of movement across the membrane ()

Answer 12

1. Diffusion
2. Active transport
3. Bulk transport
4. Osmosis

Question 13

Diffusion

Answer 13

Movement of molecules from one region to another

Question 14

Passive Diffusion

Answer 14

Move from area of high concentration to that of low concentration until equilibrium

Question 15

Passive Diffusion (through lipid bilayer)
(2 + example)

Answer 15

1. allows some molecules through and restricts others
2. Small, uncharged non-polar molecules pass easily (dissolve)
   e.g. O2, CO2, urea

Question 16

Passive Diffusion (through channels)

Answer 16

1. water and many ions diffuse though
2. some channels are always open, others gated
3. gated channels for Na, K, Ca

Question 17

Facilitated Diffusion steps (3)

Answer 17

1. molecule attaches to “transport” or “carrier” protein
2. protein changes shape to physically transfer the molecule to the other side of the membrane and release it
3. “carrier” protein returns to OG shape

Question 18

Facilitated Diffusion example

Answer 18

Glucose and other simple sugars

Question 19

Osmosis

Answer 19

diffusion of water across a selectively permeable membrane

Question 20

Osmosis direction of water

Answer 20

opposite direction of the solutes

Question 21

Active Transport

Answer 21

needs energy and moves against the concentration gradient (from low to high concentration)

Question 22

Endocytosis

Answer 22

into the cell

Question 22

sodium-potassium pump

Question 23

Exocytosis

Answer 23

out of the cell

Question 24

What is endocytosis & exocytosis used for? (2)

Answer 24

1. Larger molecules that won’t “fit” through channels or proteins
2. Bulk transport of several kinds of molecules at the same time

Question 25

Endocytosis steps

Question 26

Exocytosis steps

Question 27

Tonicity

Answer 27

the concentration of solutes in two fluids (inside and outside of the cell)

Question 28

Water will always move to the area with the _____________ solute concentration

Answer 28

higher

Question 29

Types of extracellular solutions (3)

Answer 29

1. Isotonic
2. Hypertonic
3. Hypotonic

Question 30

Isotonic

Answer 30

solute concentrations equal both inside and out
Water movement is equal

Question 31

Hypertonic

Answer 31

higher solutes outside compared to inside
Water moves OUT and cell undergoes crenation

Question 32

Hypotonic

Answer 32

higher solutes inside compared to outside
Water moves INTO the cell and the cell undergoes lysis

Question 33

Crenation

Answer 33

cells are exposed to a hypertonic solution

Question 34

Lysis

Answer 34

cells are exposed to a hypotonic solution will swell and burst