exam 2 module 5 Membrane Transport

Question 1

concentration gradient

Answer 1

a solute is more concentrated in one region than in a neighboring region.
- the image below, the tea is more highly concentrated near the tea bag than in the rest of the cup, forming a concentration gradient.

Question 2

passive transport (Does Not Require Energy Input)

Answer 2

a) diffusion- All forms of passive transport involve diffusion. the movement of a substance from a region where it is highly concentrated to an area where it is less concentrated.

Question 3

simple diffusion( No Protein Required)

Answer 3

a) example: O2 and CO2
-oxygen (O2) and carbon dioxide (CO2) can easily pass through the hydrophobic regions of the membrane. This is impossible for large polar molecules, such as glucose.

Question 4

osmosis

Answer 4

a) red blood cells (demonstrates the effect of osmosis)

i) isotonic solution(iso- equal)- the plasma’s solute concentration is the same as the inside of the cell. Therefore, water moves into and out of the cell at equal rates

ii) hypotonic solution(hypo-means under)- water moves inside the cell because the cell has more solutes. Since animal cells lack a cell wall, the membrane may even burst.

iii) hypertonic solution(hyper-means over)- it will lose water. A cell placed in a hypertonic environment loses water, shrivels, and may die.

Question 5

osmosis definition

Answer 5

simple diffusion of water across a selectively permeable membrane.

Question 6

passive transport definition

Answer 6

substance moves across a membrane without the use of energy

Question 7

plant cell

Answer 7

i) turgor pressure
ii) hypotonic solution( pic of healthy flowers)
iii) hypertonic solution- water leaves the cell, so turgor pressure is low. The plant wilts.(pic of wilting flowers)

Question 8

turgor pressure

Answer 8

force of water pressing on the plant cell wall

Question 9

facilitated diffusion

Answer 9

membrane protein assists the movement of a polar solute down its concentration gradient

Question 10

facilitated diffusion example

Answer 10

a) examples: ions (H+) and polar molecules (glucose)
-Ions (ex., H+) and polar molecules (ex., glucose) cannot pass through the hydrophobic layer of the cell membrane. Instead, transport proteins help these solutes cross

Question 11

Facilitated diffusion occurs

Answer 11

in either direction depending on the concentration gradient of the molecules.

Question 12

active transport defintion

Answer 12

moves a substance across a membrane against its concentration gradient, from where it is less concentrated to where it is more concentrated

Question 13

active transport

Answer 13

a) example: sodium-potassium (Na+/K+) pump

-Cells must contain high levels of potassium (K+) and low concentrations of sodium (Na+) to perform many functions.

• For example, essential for nerve and muscle function.

Question 14

sodium-potassium pump

Answer 14

used to create the needed gradient. The pump uses ATP as an energy source to move 3 Na+ outside the cell for every 2 K+ it admits inside the cell (figure 4.19).

Question 15

The sodium-potassium pump function is to pump

Answer 15

sodium ions out of the cell and potassium ions into the cell.

Question 16

Endocytosis and Exocytosis Use transport in vesicles

Answer 16

a) endocytosis- a cell membrane engulfs fluids and large molecules to bring them into the cell. A small portion of the membrane goes inward and traps the particles.

(The two main forms of endocytosis are pinocytosis and phagocytosis.)

i) pinocytosis- cell engulfs small amounts of fluid and dissolved substances

ii) phagocytosis- cell captures and engulfs large particles, such as debris and even another cell

iii) receptor-mediated endocytosis- form of endocytosis in which receptor proteins on the cell surface are used to capture specific target molecules that are engulfed into the cell.

Question 17

Endocytosis and Exocytosis Use transport in vesicles

Answer 17

a) endocytosis- a cell membrane engulfs fluids and large molecules to bring them into the cell. A small portion of the membrane goes inward and traps the particles.

(The two main forms of endocytosis are pinocytosis and phagocytosis.)

i) pinocytosis- cell engulfs small amounts of fluid and dissolved substances

ii) phagocytosis- cell captures and engulfs large particles, such as debris and even another cell

iii) receptor-mediated endocytosis- a form of endocytosis in which receptor proteins on the cell surface are used to capture specific target molecules that are engulfed into the cell.

Question 18

Endocytosis and Exocytosis Use transport in vesicles part 2

Answer 18

b) exocytosis
- the opposite of endocytosis. The process uses vesicles to transport fluids and large particles out of cells

Question 19

Which of the following are examples of exocytosis?

Answer 19

a. The release of antibodies from white blood cells

b. A macrophage engulfing a pathogen to destroy it

c. The transport of chemical messengers (or neurotransmitters) out of nerve cells

d. The absorption of water by a red blood cell

the answer is a and c,
a.
During exocytosis, materials are transported from the inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane. The release of antibodies from white blood cells is a form of this process.

c.
During exocytosis, materials are transported from the inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane. The outward transport of neurotransmitter is a form of this process.