Chapter 7 - Membranes

Question 1

3 Functions of cell membranes

Answer 1

1. Selectively permeable barrier (in and out)
2. Protein Anchor
3. Energy Metabolism

Question 2

Phospholipids are not:

Answer 2

Stationary

Question 3

Animal Cell Membranes containing cholesterol: (2)

Answer 3

• cholesterol hinders packing

- membranes become less fluid at low temperatures due to tight packing of lipids

Question 4

Peripheral proteins

Answer 4

Loosely bound to the membranes surface

Question 5

Integral protein

Answer 5

Penetrate the hydrophobic interior of the lipid bilayer. They SPAN the membrane and are mostly trans membrane proteins

Question 6

Amphipathic molecule

Answer 6

It has both a hydrophobic and hydrophilic region

Question 7

Transmembrane Receptor Proteins

Answer 7

Attachment sites for other cells, viruses, molecules recognition, communication, signal transduction.

Ex: insulin binds to a membrane receptor and triggers a response

Question 8

Transmembrane Enzymes

Answer 8

Enzymes involved in energy metabolism

Question 9

Membrane Transport Proteins (3)

Answer 9

• lipid bilayer is impenetrable to most molecules
• nonpolar molecules pass through hydrophobic core of membrane
• polar and ionic molecules cannot cross and must be transported by specific transmembrane channels or carrier proteins

Question 10

Passive Diffusion Across Membrane

Answer 10

• substances diffuse from region of high concentration to region of low concentration (down concentration gradient)
• concentrations in both regions are equal
• doesn’t require energy

Question 11

Diffusion

Answer 11

The movement of particles of any substance so that they spread out into available space

Question 12

Prefix GLYCO

Answer 12

Referring to carbohydrates

Question 13

Concentration Gradient

Answer 13

The region along which the density of a chemical substance increases or decreases

Question 14

Passive Transport

Answer 14

The diffusion of a substance across a biological membrane

Question 15

Osmosis

Answer 15

The diffusion of free water across a selectively permeable membrane, whether artificial or cellular. Moves down concentration gradient

Question 16

Tonicity

Answer 16

The ability of a surrounding solution to cause a cell to gain or lose water

Question 17

Isotonic Solution

Answer 17

Solute concentration on both sides of membrane is the same. No net movement of water

Question 18

Hypertonic solution

Answer 18

When external environment has higher solute concentration relative to cytoplasm. Cells lose water and shrink

Question 19

Hypotonic Solution

Answer 19

When external environments has a lower solute concentration relative to the cytoplasm. Cells gain water and burst

Question 20

Facilitated Diffusion (4)

Answer 20

• specific transport proteins increase rate of diffusion
• solutes diffuse through protein down concentration gradient
• proteins often change shape when solute Binds
• change in shape permits translocation of solute

Question 21

Active Transport

Answer 21

To move solutes against their concentration gradient, which requires energy (often atp)

Question 22

Bulk Transport

Answer 22

• large substances transported across membrane via membrane bound vesicles.
• vesicles and cell membrane FUSE

Question 23

Exocytosis

Answer 23

Export of large molecules from cell

Question 24

Membrane Potential

Answer 24

The voltage across the membrane

Question 25

Endocytosis

Answer 25

Large substances can ENTER cells via endocytosis