UNIT TEST 1: Intro To Membrane Transport (Ch.3, Pt.2)

Question 1

What is a SUBSTANCE?

Answer 1

It’s a solute or a solvent material

Question 2

What are the definitions used when it comes to substances or solutions transport in the body?

Answer 2

IN SUBTANCES:
- Concentration gradient
- Diffusion

IN SOLUTIONS:
- Solvent
- Solute

Question 3

What’s a SOLUTION?

Answer 3

It’s Solvent + Solute

Question 4

What’s “CONCENTRATION GRADIENT”?

Answer 4

The difference in concentration of a substance between two regions (Ex. The inside and outside of a cell).
If there is no difference, then there is no concentration gradient.

Question 5

What’s “DIFFUSION”?

Answer 5

Movement of particles/molecules from a high concentration to a low concentration area until evenly distributed.

The membrane between the two areas can let H2O pass thru but not solutes. Volume increases in the higher osmolarity (more solute) area.

Question 6

What is “SOLVENT’”?

Answer 6

Most abundant substance in a solution. (Usually liquids)

Question 7

What is “SOLUTE”?

Answer 7

Less abundant substance in a solution. Ex. Proteins, aminoacids, vitamins, etc.

Question 8

What are the two types of mechanisms for Membrane Transport?

Answer 8

PASSIVE & ACTIVE processes

Question 9

Explain “Passive Transport Processes”

Answer 9

• No energy required (no ATP)
• Substance moves from a region of high concentration to a a lower. DIFFUSION
• with the “Concentration gradient”

Question 10

Explain “Active Transport Processes”

Answer 10

• Require energy (ATP)
• Solute can move from a region of lower concentration to a higher (allowing large and water soluble substances to cross the membrane.
  -allows transport of substances against the “Concentration gradient “
• require specific Carrier proteins
• There are two types: “Sodium(Na+)/Potassium(K+) Pump” & “Vesicular (Bulk) Transport”.

Question 11

What are the TYPES of “Passive Transport Mechanisms”?

Answer 11

Simple diffusion
Facilitated diffusion
Osmosis

Question 12

What’s “Simple diffusion”?

Answer 12

• Small particles and lipid soluble (nonpolar) subtances can cross the membrane (anything that dissolves into the lipid).
  Ex. O2, CO2, fat soluble vitamins, alcohol.

Question 13

What’s “Facilitated diffusion”?

Answer 13

• Molecules that are unable to pass through the membrane due to polarity, size can passively pass via CARRIER (ex. sugars, amino acids) & CHANNEL PROTEINS (ex. water, ions).
• HIGHLY SELECTIVE & SPECIFIC

Question 14

What’s “Osmosis”?

Answer 14

Diffusion of solvent (usually H2O) through a selective permeable membrane.

• Polar water can pass through the nonpolar membrane (bcs of the movement of the membrane).
• Follows concentration gradient: from more H20 (solvent) to where is less solvent.
• Different environments the cells can be: ISOTONIC, HYPOTONIC & HYPERTONIC

Question 15

What are the different ways the water moves/diffuses depending on the cellular ENVIROMENT the cell is placed in? (In other words the OSMOLARITY between the cell & the environment).

What do they each indicate?

Answer 15

ISOtonic environment = equal SOLUTE concentration inside & outside the cell. (No effect on the volume)

HYPOtonic environment= lesser SOLUTE concentration outside the cell (Cell. SWELLS/BURST; hemolysis) H2O enters cell.

HYPERtonic environment= greater SOLUTE concentration outside the cell (Cell SHRINKS/CRENATES). H2O leaves the cell.

Question 16

Explain “Membrane Permeability”

Answer 16

A substance can cross the plasma membrane only if the membrane is PERMEABLE to that substance.

If the Membrane is permeable to both solute & solvent (ex. H2O); both areas (solutions) will have same osmolarity / same volume

If the membrane is permeable to the solvent (Ex. H20) & impermeable to the solutes (called semipermeable membrane: small holes allow only the H20 to pass); results in same osmolarity, but greater volume from one side

Question 17

What does it mean Higher, Lesser or Equal “Osmolarity”?

Answer 17

Higher, lesser or equal concentration solute in the environment (outside the cell).

Question 18

What’s the Na+/K+ Pump? What’s its function?

Answer 18

Is a “Carrier protein” in the plasma membrane of all cells.

• Pumps Na+ out of the cell & pumps K+ into the cell; against the concentration gradient/ natural diffusion.
• Concentration of Na+ higher OUTside the cell. K+ higher INside the cell (essential for cells to have proper volume fro reactions to take place): muscle & nerve cells.

Question 19

What’s the “Vesicular (Bulk) Transport”?
What’s its function?

Answer 19

Sacs called ‘Vesicles” surrounded by the e membrane.

• Transport fluid & large molecules across the membrane
• Many molecules are moved at the same time (BULK transport)
• Types of Vesicular transport: EXOcytosis, ENDOcytosis & PHAGOcytosis.

Question 20

Explain EXOcytosis

Answer 20

A type of Vesicular Transport

Substances move to the “extracellular” (outside the cell): The Golgi apparatus enclose the substances in a “Vesicle” , then this one migrates to the plasma membrane and spills the content outside.

Question 21

Explain ENDOcytosis

Answer 21

A type of Vesicular Transport

Substances move into the cell (inside) from the outside.

THE OPPOSITE OF EXOCYTOSIS!

Question 22

Explain PHAGOcytosis

Answer 22

A type of Vesicular Transport

Pseudopods (cytoplasmic extensions) surround and swallow the material (bacteria, virus,etc) from outside into the of the cell. Ex. Macrophages & some WBC’s cells.

Then, a vesicle is formed (called “Phagosome”, it fuses with a Lysosome & the materials are digested.

Question 23

Does the plasma membrane expand as a result of ENDOcytosis or EXOcytosis?

Answer 23

EXOcytosis (the vesicles migrate to the P.M to export material to the outside= more volume there).