1.4 Cell Membrane

Question 1

Cell membranes are

Answer 1

Selectively permeable

Question 2

Fluid Mosaic Model

Answer 2

Membranes are held together by weak interactions (fluid) and are composed of phospholipids, proteins, and carbs (mosaic)

Question 3

Amphipathic

Answer 3

Hydrophilic head, hydrophobic tail

Question 4

Function of hydrophobic barrier (core)

Answer 4

Keeps hydrophilic molecules out, including ions and large polar molecules

Question 5

What does the cell membrane allow in

Answer 5

Small molecules (polar or nonpolar) cross easily (hydrocarbons, hydrophobic molecules, CO2, O2)

Question 6

Polar

Answer 6

Unequal sharing of electrons (H2O, SO2)

Question 7

Non-polar

Answer 7

Equal sharing of electrons (O2, CO2)

Question 8

Function of cholesterol in cell membranes

Answer 8

Resist changes in membrane fluidity; limit fluidity at high temperatures and hinder close packing at low temperatures

Question 9

How are cell membranes adapted at low temperatures

Answer 9

Contain phospholipids with unsaturated tails; kinks prevent close packing

Question 10

2 types of membrane proteins

Answer 10

Integral proteins and peripheral proteins

Question 11

Integral proteins

Answer 11

Embedded in membrane; contain transmembrane with hydrophilic heads/tails and hydrophobic middles

Question 12

Peripheral proteins

Answer 12

Extracellular side of membrane; held in place by ECM or cytoskeleton and provides stronger framework

Question 13

Functions of membrane proteins

Answer 13

Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to ECM

Question 14

Function of carbohydrates in cell membrane

Answer 14

Cell-cell recognition and cell protection (glycolipids and glycoproteins)

Question 15

Example of carbohydrate function in cell membrane

Answer 15

Type-specific blood transfusion