Chapter 6: Interactions Between Cells and the Extracellular Environment

Question 1

What is passive transport?

Answer 1

Movement of substances across a cell membrane without the use of energy (ATP)
Passive transport includes processes such as diffusion and osmosis.

Question 2

Does passive transport require energy?

Answer 2

No
Passive transport occurs down a concentration gradient.

Question 3

What is the direction of movement in passive transport?

Answer 3

Down a concentration gradient

This means substances move from areas of higher concentration to areas of lower concentration.

This means substances move from areas of higher concentration to areas of lower concentration.

Question 4

What are two types of passive transport?

Answer 4

• Diffusion
• Osmosis

Diffusion refers to the movement of molecules from high to low concentration, while osmosis specifically refers to the movement of water.

Question 5

What is active transport?

Answer 5

Movement of substances across a cell membrane that requires energy (ATP)

Active transport often involves the use of protein pumps.

Question 6

Does active transport require energy?

Answer 6

Yes, Active transport requires energy to move substances against their concentration gradient.

Question 7

What is the direction of movement in active transport?

Answer 7

Up a concentration gradient

This means substances move from areas of lower concentration to areas of higher concentration.

Question 8

What is needed for active transport to occur?

Answer 8

Energy (ATP) and a pump

Pumps are specialized proteins in the cell membrane that facilitate active transport.

Question 9

What is the state of motion of molecules in a solution?

Answer 9

Constant state of motion
Refers to the kinetic activity of molecules in a liquid medium.

Question 10

What is the term for the random movement of particles in a fluid?

Answer 10

Brownian movement

Named after the botanist Robert Brown who first observed this phenomenon.

Named after the botanist Robert Brown who first observed this phenomenon.

Question 11

What process establishes equilibrium when there is a concentration difference between two regions?

Answer 11

Diffusion

This process involves the movement of molecules from an area of higher concentration to an area of lower concentration.

Question 12

Diffusion obeys which law of thermodynamics?

Answer 12

2nd Law of Thermodynamics

This law states that in any energy exchange, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state.

Question 13

What effect does diffusion have on entropy?

Answer 13

Increases entropy

Entropy is a measure of disorder, and diffusion leads to a more disordered state.

Question 14

What are solutions?

Answer 14

Consists of a solvent (water) and a solute (molecules dissolved in water)

Question 15

Solution

Answer 15

Solutes dissolve in water

Question 16

Colloid

Answer 16

Mix of proteins and water (like milk)

Question 17

Suspension

Answer 17

Large particles suspended in liquid (separate when still)

Question 18

Emulsion

Answer 18

Suspension of a liquid in a liquid

Question 19

Simple diffusion

Answer 19

Small, nonpolar molecules/lipid soluble (O2).

Question 20

Facilitated diffusion

Answer 20

carrier mediated, uses a carrier protein. Conformational change, high to low, glucose, aquaporins

Question 21

What are the factors affecting diffusion rate through a membrane?

Answer 21

• Increase in temperature (increase kinetic energy of molecules)
• Increase in molecular weight (slows movement)
• Increase in membrane surface area
• Increase in membrane permeability

Question 22

Paracellular Routes

Answer 22

Substances pass through gaps between the cells

Question 23

Transcellular

Answer 23

Substances pass through cells

Question 24

Question 25

Types of ion channels

Answer 25

Ligand gates (requires chemical), mechanically gates, always open (leaks), voltage gated

Question 26

What is osmosis?

Answer 26

Diffusion of water across a membrane

Question 27

What are osmotically active solutes?

Answer 27

Solutes that cannot pass through a membrane, therefore, promote osmosis

Question 28

Define osmolarity.

Answer 28

Molality of solutes (i.e. 300 mOsm/L)

Question 29

What does tonicity refer to?

Answer 29

Ability of a solution to “pull” water

Question 30

What is the consequence of low protein in the blood for a child?

Answer 30

Decrease in blood volume

Question 31

How does low protein lead to kwashiorkor?

Answer 31

Swelling of the abdomen, hands, or feet from fluid accumulation in tissues due to malnutrition

Question 32

What effect does giving a patient an IV of distilled water have on blood plasma?

Answer 32

Makes the blood plasma hypotonic compared to the RBCs

Question 33

Why can administering distilled water IV be deadly?

Answer 33

It can lead to cell lysis due to osmotic imbalance

Question 34

What is the purpose of sports drinks like Gatorade?

Answer 34

To hydrate the body’s tissues

Question 35

Is Gatorade isotonic, hypertonic, or hypotonic to the body’s tissues?

Answer 35

Isotonic

Question 36

What is the tonicity of ocean water compared to a sailor’s body tissues?

Answer 36

Hypertonic

Question 37

When drinking ocean water, will water move from the bloodstream into the tissues or from the tissues into the bloodstream?

Answer 37

From the tissues into the bloodstream

Question 38

What effect does excess fertilizer have on soil tonicity?

Answer 38

Makes the soil hypertonic

Question 39

Which way will water be pulled in a hypertonic environment?

Answer 39

Water will be pulled out of the plant

Question 40

What happens to the plant in a hypertonic environment?

Answer 40

The plant will wilt or undergo plasmolysis

Question 41

What is passive transport?

Answer 41

Requires no energy (ATP) and occurs down a concentration gradient

Question 42

What is active transport?

Answer 42

Requires energy (ATP) and a pump to move substances up a concentration gradient

Question 43

Vesicular transporter

Answer 43

moves large particles, fluid droplets, or numerous molecules at once through the membrane in vesicles—bubble-like enclosures of membrane

Question 44

Active transport

Answer 44

Vesicular fusion uses GTP

Question 45

Endocytosis

Answer 45

Vesicular processes that bring material into cell

Question 46

Phagocytosis

Answer 46

Engulfs large particles and digests them

Question 47

Pinocytosis

Answer 47

"cells drinking" intake of ECF and dissolved solutes

Question 48

Receptor-mediated endocytosis

Answer 48

Ligand bind to a receptor to cause endocytosis

Question 49

Clathrin

Answer 49

Protein complex, coats vesicles, "ID tag" for cellular transport

Question 50

ACE2

Answer 50

Cell receptor, converts angiotensin II to angiotensin Angiotensin lowers BP.

Question 51

Exocytosis

Answer 51

Vesicular transport to discharge material from the cell

Question 52

What do SNARE proteins interact with?

Answer 52

They interact with each other on opposing membranes to initiate membrane fusion

Question 53

Membrane Potential: There is a difference in charge on each side of the plasma membrane due to:

Answer 53

Action of Na+/K+ pumps

Question 54

Membrane potential and what it depends on

Answer 54

potential difference across a membrane Depends on: Concentration gradient Membrane permeability

Question 55

Nernst equation

Answer 55

Calculates an ion’s equilibrium potential. Voltage necessary to oppose the net movement of an ion down its concentration gradient Law of electrical neutrality + = –

Question 56

Question 57

Gap junctions

Answer 57

Gap junctions allow small solutes to pass directly into a neighboring cell

Question 58

Signaling via Receptor Proteins: hydrophilic and hydrophobic

Answer 58

Hydrophilic – doesn’t enter cell on its own Hydrophobic – crosses membrane to enter cell