Ch 3B Unit 3

Question 1

Cell Membrane

Answer 1

The cell membrane, or the plasma membrane, forms a boundary between a cell and the outside environment and controls the passage of materials into and out of a cell

Question 2

Phospolipid

Answer 2

a molecule composed of 3 parts 1. charged phosphate group 2. Glycerol 3. two fatty acid chains;

Question 3

Fluid Mosaic Model

Answer 3

describes the arrangement of the molecules that make up the cell membrane

Question 4

Selective Permeability

Answer 4

allows some though not all material to cross the cross; border guards

Question 5

Receptor

Answer 5

Protein that detects a signal molecule and performs an action in response

Question 6

“Head” of Phospholipid

Answer 6

The fatty acids form the“tail.” Because the head bears a charge, it is polar.

Question 7

“Tail” of Phospholipid

Answer 7

The fatty acid tails are nonpolar and cannot form hydrogen bonds with water.

Question 8

Polar vs. Nonpolar Parts of Phospholipid

Answer 8

Polar forms the outer surfaces of the membrane, where they interact with the watery environment both outside and inside a cell. The nonpolar tails are like the filling.

Question 9

Cholesterol Molecules

Answer 9

Cholesterol is an important component of the membranes of cells, providing stability. It is the major precursor for the synthesis of vitamin D, of the various steroid hormones, including cortisol, cortisone, and aldosterone in the adrenal glands, and of the sex hormones progesterone, estrogen, and testosterone. Cholesterol molecules strengthen the cell membrane.

Question 10

Membrane Proteins

Answer 10

Some proteins extend through one or both phospholipid layers and help materials cross the membrane. Other proteins are key components of the cytoskeleton.

Question 11

Carbohydrates

Answer 11

Carbohydrates attached to membrane proteins serve as identification tags, enabling cells to distinguish one type of cell from another.​

Question 12

Selective Permeability

Answer 12

The cell membrane has the property of selective permeability, which means it allows some, but not all, materials to cross.

Question 13

Receptor

Answer 13

A protein that detects a signal molecule and performs an action in response.

Question 14

Intracellular Receptor

Answer 14

A molecule may cross the cell membrane and bind to an intracellular receptor.

Question 15

Membrane Receptor

Answer 15

A molecule that cannot cross the membrane may bind to a receptor in the cell membrane.