Lecture 7

Question 1

Simple Diffusion

Answer 1

The unaided movement of a solute across a membrane, dictated by concentration differences on the two sides of the membrane, typically possible for gases, non-polar molecules, or small polar molecules

Question 2

Osmosis

Answer 2

The movement of water across a selectively permeable membrane (allows water to pass but not the solute), water moves toward the region of higher solute concentration

Question 3

Hypertonic

Answer 3

Greater solute concentration outside the cell, water flows out of the cell

Question 4

Hypotonic

Answer 4

Greater solute concentration inside the cell, water flows into the cell

Question 5

Facilitated Diffusion

Answer 5

The diffusion of large/polar molecules across a membrane with the assistance of transport proteins, doesn’t require energy

Question 6

Channel Proteins

Answer 6

Integral membrane proteins which form a hydrophilic channel through the membrane to provide a passage for solutes

Question 7

Carrier Proteins

Answer 7

Integral membrane proteins which bind solute molecules on one side of a membrane, undergo a conformational change and release a specific number of solute molecules on the other side of the membrane

Question 8

Ion Channels

Answer 8

Channel proteins which form pores lined with hydrophilic atoms that are remarkably selective, often gated, used for cellular communication, muscle contraction, nerve cell signalling and maintaining homeostasis

Question 9

Porins

Answer 9

Pores on the outer membranes of bacteria, mitochondria and chloroplasts, larger and less selective than ion channels, have a beta barrel structure

Question 10

Aquaporins

Answer 10

Pores which allow the rapid passage of water through membranes of erythrocytes and kidney cells

Question 11

Alternating Conformational Model

Answer 11

States that a carrier protein alternates between two conformational states

Question 12

Uniporter

Answer 12

A carrier protein that transports a single solute across the membrane

Question 13

GLUT1

Answer 13

A glucose transporter in erythrocytes, an integral membrane protein with 12 transmembrane segments which form a a variety with hydrophilic side chains

Question 14

Hexokinase

Answer 14

An enzyme which uses ATP to convert glucose to glucose-6-phosphate so that it can no longer bind carrier proteins

Question 15

Symporter

Answer 15

A carrier protein which transports two solutes in the same direction across the membrane

Question 16

Antiporter

Answer 16

A carrier protein which transports two solutes in opposite directions across the membrane

Question 17

Active Transport

Answer 17

Movement of a solute up a concentration gradient, couples endergonic transport to an exergonic process, used for the uptake of nutrients, removal of waste and maintenance of disequilibrium

Question 18

Direct Active Transport

Answer 18

Involves a transport system coupled to an exergonic chemical reaction (ATP hydrolysis)

Question 19

Indirect Active Transport

Answer 19

Secondary active transport, involves the coupled transport of a two substances, where the the diffusion of one substance drives the movement of another substance against its gradient

Question 20

Bacteriorhodopsin

Answer 20

A small integral membrane protein found in archaea, uses energy from photons of light to drive the active transport of protons and create an electrochemical proton gradient that power the synthesis of ATP