Unit III transport

Question 1

State the 7 cells functions (six of them are due to proteins).

Answer 1

Contains and defines the cell, selective transport, enzyme activity, signal transduction, cell recognition, cell adhesion, attachement to cytoskeleton.

Question 2

State the three types of passive transport.

Answer 2

Diffusion, facilitated diffusion and osmosis.

Question 3

What is passive transport?

Answer 3

It is a type of traffic between cells that does not required direct energy.

Question 4

Describe diffusion.

Answer 4

It is the movement of particles down a concentration gradient from high to low concentration.

Question 5

What are molecules that can readily diffuse?

Answer 5

CO2, O2 or lipid soluble-molecules.

Question 6

What is osmosis?

Answer 6

It is the transport of water across membranes, either through the membranes or through aquaporins which are protein channels that allow the passage of water. Water moves from hypertonic to hypotonic until isotonic.

Question 7

Explain why using salt as a preservative is an example of osmosis.

Answer 7

When the concentration of salt is higher outside of the bacteria than inside, the water is drawn out of the cells. There is less water which is less than ideal conditions.

Question 8

What is facilitated diffusion?

Answer 8

It is the transport of solutes down a gradient through specific protein channels.

Question 9

Give two examples of facilitated diffusion?

Answer 9

glucose transporters and gated ion channels in neurons.

Question 10

What is active transport?

Answer 10

It is moving substances across membranes against their gradient. It requires trans membraneproteins (pumps) and energy as ATP.

Question 11

What are ion pumps?

Answer 11

They transport ions against their gradient, maintaining osmotic potential and the electrochemical gradient.

Question 12

Where is situated the Ca++ pump?

Answer 12

In muscle cells in the membrane of the sarcoplasmic reticulum.

Question 13

Give two function of the H+ pump and the domain of organisms which have it the most?

Answer 13

It is most common in plants, fungi and bacteria. It is found in the lysosome membrane to maintain the acid pH inside of it. It is also found in mitochondria, and is used to make an H+ gradient for the synthesis of ATP.

Question 14

What is the function of the H+/K+ pump?

Answer 14

It is in the stomach to pump H+ into the lumen.

Question 15

Explain what co-transport is.

Answer 15

In co-transport, two molecules move through the same transport molecule. One moves down its gradient, which indicates the need for a concentration gradient and the other moves against its gradient. The ATP use is indirect.

Question 16

What are the two types of co-transport?

Answer 16

There is symport: the two molecules move in the same direction, e.g. H+/sucrose co-transporter. There is also anti-port: 2 molecules move in opposite direction, e.g. Ca++/Na+ exchanger.

Question 17

Explain what exocytosis is.

Answer 17

Exocytosis is the movement of molecules outside of the cell, from a vesicle inside to the outside. The vesicle fuses with the membrane. It requires ATP.

Question 18

Secretion of neurotransmitters, secretion of hormones, secretion of enzymes, the making of more membrane, the insertion of transmembrane molecules and the antigen are all example of what?

Answer 18

Exocytosis.

Question 19

Explain what endocytosis is.

Answer 19

Endocytosis is the uptake of macromolecules from the outside using a vesicle from the membrane.

Question 20

What are the three types of endocytosi?

Answer 20

Receptor mediated endocytosis, phagocytosis and pinocytosis.

Question 21

What is receptor mediated endocytosis?

Answer 21

It is when specific molecules bind to receptors, e.g. uptake of cholesterol.