Transport Of Ions And Small Molecules

Question 1

Diffusion

Answer 1

Random molecular motion of solute down a chemical or electrochemical gradient

How move across membrane

Question 2

Osmosis

Answer 2

Diffusion of water across a semipermeable membrane

Question 3

Protein mediated transport

Answer 3

More rapid than simple diffusion

Substrate for molecule movement

Saturation kinetics and chemical specificity and stereospecificy because only certain molecules are transported

Question 4

Saturation kinetics

Answer 4

Rate of transport increases until it reaches a point at which is stabilizes

There’s a limit only so many proteins so can only move so many molecules

Question 5

Facilitated vs. simple diffusion

Answer 5

Simple is linear

Facilitated if add proteins rate will increase

Question 6

Allosteric binding sites

Answer 6

To control conformation of proteins and regulates transport

Glucose binding is competitive inhibition

Question 7

Competitive inhibition

Answer 7

Is molecule binds site instead of glucose it blocks glucose binding to the protein and suppresses glucose transport

Lots of therapeutic agents, ex is antihistamines

Question 8

Types of protein mediated transport

Answer 8

Facilitated transport

Active transport

Question 9

Facilitated transport

Answer 9

Not linked to metabolic energy because moves down gradient and not blocked by substrate

Cannot move against electrical potential because requires energy

Cannot move uncharged particles against a gradient

Transported molecule may alter transport by producing conformational change in the transport protein

Question 10

Active transport

Answer 10

ATP required, hydrolysis is needed to move against gradient, foundation of membrane potential

Metabolic inhibitors can block

Substances can move against concentration gradients

Question 11

Membrane potential

Answer 11

Requires active transport

Question 12

Types of transport proteins

Answer 12

Carrier proteins which bind molecules and move across membrane via conformational change

Channel proteins which have pores that open and close transmitting certain molecules across the membrane

Question 13

Uniport

Answer 13

One type of molecule is transported across the membrane

Question 14

Symport

Answer 14

Two different molecules transported in same direction

Question 15

Antiport

Answer 15

Two different molecules transported in different directions

Question 16

Types of channels

Answer 16

Open, closed, active transport, conformational transformation

ATP pump, ion channel which has greatest rate of transport and transporter

Question 17

Carrier proteins

Answer 17

Can be active of facilitated transport

Uniporter, symporter, antiporter

Question 18

Na, K ATPase

Answer 18

Most important ion transport via carrier proteins in the body

Maintains Low Na and high K in the cell by active transport and is responsible for membrane potential

3 Na out and 2 K in for each ATP hydrolyzed to ADP

2/3 of neurons energy needed here

Phosphorylation and dephosphorylation regulates

Chemical potential energy created and used to drive other systems ex: kidney

1 gate open at time creates specificity

Question 19

Ca ATPase

Answer 19

Important in muscle

Question 20

Na Ca Antiporter

Answer 20

Important in the heart

Question 21

Na H antiport

Answer 21

PH of cytoplasm

Question 22

Chloride bicarbonate antiporter

Answer 22

Important for pH

Question 23

Na K Cl symporter

Answer 23

All at the same time

LasX binds to chloride symporter

Question 24

Ion transport channels

Answer 24

Transmembrane alpha helicopter

b subunit forms a physical gate on outside of cell which opens to activate channel

Specificity not just dependent on molecule itself, ex: Na smaller than K but transports with water so cannot fit through K channel

Question 25

Voltage gated channel

Answer 25

Ion transport channel

Activated by changes in membrane potential

Exist for Na, K and Ca

Different channels can be activated by depolarization or hyperpolarization

Question 26

Ligand gated channel

Answer 26

Activated by ligand binding receptor which then opens the gate

Ketamine blocks this for Na and Cl which is activated by glutamate
Ketamine Blocks depolarization (making +) so no generation of action potential