Unit 3: Membrane Transport and Functions

Question 1

This controls what enters and exits the cell to maintain homeostasis

Answer 1

Cell Membrane

Question 2

This provides protection and support for the cell

Answer 2

Cell Membrane

Question 3

What is the structure of the cell membrane?

Answer 3

• lipid bilayer
• hydrophilic phosphate head
• hydrophobic fatty acid tail
• proteins embedded in membrane

Question 4

[…] and […] proposed in 1972 that the membrane is a mosaic of proteins dispersed within the bilayer, with only the hydrophilic regions exposed to water

Answer 4

• S.J. Singer
• G. Nicolson

Question 5

The 6 membrane proteins

Answer 5

• integral proteins
• pumps
• channel proteins
• carrier proteins
• enzyme proteins
• receptor proteins

Question 6

Membrane Protein

Make up 70% of cell membrane proteins, permanently embedded within the cell membrane

Answer 6

Integral Proteins

Question 7

Membrane Protein

Transfer substances against concentration and electrical gradients using ATP

Answer 7

Pumps

Question 8

Membrane Protein

Transfer substances down concentration and electrical gradients, opened and closed by “gates”

Answer 8

Channel Proteins

Question 9

Membrane Protein

Involved in the transport of specific substances by changing shape when bound to certain substances

Answer 9

Carrier Proteins

Question 10

Membrane Protein

Catalyze membrane reactions

Answer 10

Enzyme Proteins

Question 11

Membrane Protein

Bear appropriate sites for recognition of specific ligands

Answer 11

Receptor Proteins

Question 12

The 2 types of membrane proteins

Answer 12

• peripheral proteins
• integral proteins

Question 13

Type of Membrane Protein

Bound to the surface of the membrane

Answer 13

Peripheral Proteins

Question 14

Type of Membrane Protein

Penetrate the hydrophobic core

Answer 14

Integral Proteins

Question 15

The 6 functions of cell membrane proteins

Answer 15

• transport
• enzymatic activity
• signal transduction
• cell-cell recognition
• intercellular joining
• attachment to cytoskeleton and extracellular matrix

Question 16

Cell recognize each other by […]

Answer 16

binding to surface molecules (often containing carbohydrates)

Question 17

HIV binds to this receptor protein to infect a cell

Answer 17

CCR5

Question 18

These proteins allow passage of hydrophilic substances across the cell membrane

Answer 18

Transport Proteins

Question 19

Transport proteins with a hydrophilic channel that certain molecules or ions can use as a tunnel

Answer 19

Channel Proteins

Question 20

Channel proteins called […] facilitate the passage of water

Answer 20

aquaporins

Question 21

Transport proteins that bind to molecules and change shape to shuttle them across the membrane

Answer 21

Carrier Proteins

Question 22

The tendency for molecules to spread out evenly into available space down their concentration gradient

Answer 22

Diffusion

Question 23

The diffusion of a substance across a biological membrane

Answer 23

Passive Transport

Question 24

The 5 factors that influence diffusion rates

Answer 24

• distance
• molecular size
• temperature
• steepness of concentration gradient
• membrane surface area

Question 25

Diffusion across membranes that do not require membrane proteins nor energy

Answer 25

Simple Diffusion

Question 26

Diffusion across membranes that requires membrane proteins but not energy

Answer 26

Channel-Mediated Diffusion

Question 27

The diffusion of water across a selectively permeable membrane

Answer 27

Osmosis

Question 28

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

Answer 28

Tonicity

Question 29

**Tonicity** Solute concentration is equal outside and inside the cell; No net water movement

Answer 29

Isotonic Solution

Question 30

**Tonicity** Solute concentration is greater outside than inside the cell; cell loses water

Answer 30

Hypertonic Solution

Question 31

**Tonicity** Solute concentration is less outside than inside the cell; cell gains water

Answer 31

Hypotonic Solution

Question 32

Effects of hypotonic solution to [animal] and [plant] cells

Answer 32

- lysed - turgid (normal)

Question 33

Effects of isotonic solution to [animal] and [plant] cells

Answer 33

- normal - flaccid

Question 34

Effects of hypertonic solution to [animal] and [plant] cells

Answer 34

- shriveled - plasmolyzed

Question 35

A lethal effect in cells wherein the membrane pulls away from the cell due to water loss

Answer 35

Plasmolysis

Question 36

A type of passive transport aided by proteins

Answer 36

Facilitated Diffusion

Question 37

Transport that moves substances against their concentration gradients using energy

Answer 37

Active Transport

Question 38

The voltage difference across a membrane

Answer 38

Membrane Potential

Question 39

Created by differences in the distribution of positive and negative ions across a membrane

Answer 39

Voltage

Question 40

The combined forces that drive the diffusion of ions across a membrane

Answer 40

Electrochemical Gradient - chemical force (ion's concentration gradient) - electrical force (effect of membrane potential on ion's movement)

Question 41

A transport protein that generates voltage across a membrane

Answer 41

Electrogenic Pump

Question 42

The main electrogenic pump of plants, fungi, and bacteria

Answer 42

Proton Pump

Question 43

Transport that occurs when active transport of a solute indirectly drives transport of other solutes

Answer 43

Cotransport

Question 44

Transport that occurs by exocytosis and endocytosis

Answer 44

Bulk Transport

Question 45

**Bulk Transport** Transport vesicles migrate to the membrane, fuse with it, and release their contents to the outside

Answer 45

Exocytosis

Question 46

The 3 types of endocytosis

Answer 46

- phagocytosis (cellular eating) - pinocytosis (cellular drinking) - receptor-mediated endocytosis

Question 47

**Bulk Transport** Cell forms vesicles from the plasma membrane to take in macromolecules

Answer 47

Endocytosis