Cell Transport

Question 1

passive transport

Answer 1

diffusion of a substances across a membrane with NO energy investment

• diffuse down the concentration gradient, high to low
• 3 types

Question 2

Simple diffusion

Answer 2

• a type of passive transport
• through membrane with no transport or carrier protein necessary
• ex. O2, CO2, lipids

Question 3

Osmosis

Answer 3

• passive transport
• diffusion of water
• water moves from [high]=> [low]; moves toward side with more solute

Question 4

Facilitated diffusion

Answer 4

• for larger polar or charged molecules that can not pass through the membrane
• needs a transport protein, but still NO energy
• ex. glucose, Na+

Question 5

Active transport

Answer 5

• requires energy
• moves against the concentration gradient using ATP hydrolysis
• use carrier proteins

Question 6

Primary active transport

Answer 6

uses ATP directly

-ex. Na+/K+ pump

Question 7

Secondary active transport (cotransport)

Answer 7

energy does not directly come from ATP, active transport of a solute INDIRECTLY drives transport of other substances

• diffusion of actively transported solute down its concentration gradient coupled with transport of 2nd substance against its own concentration gradient
  ex. Proton pump uses ATP and indirectly powers the H+/sucrose cotransporter

Question 8

Exocytosis

Answer 8

transport vesicles migrate to membrane, fuse with it, and release contents outside of the cell
-export products

Question 9

Endocyctosis

Answer 9

cells take in macromolecules by forming vesicles from plasma membrance

Question 10

Phagocytosis

Answer 10

Cell eating, engulfs a particle in a vacuole

-fuses with a lysosome to digest

Question 11

pinocytosis

Answer 11

molecules dissolves in droplets are taken up; cell drinking= invagination

Question 12

receptor-mediated endocytosis

Answer 12

bind specific solutes to receptors to trigger vesicle formation
-receptor proteins, receptors, molecules from extracellular fluid are transported in vesicles

Question 13

Effects of cholesterol on fluidity

Answer 13

• at warm temperatures cholesterol restrains movement of phospholipids
• at cool temp it maintains fluidity by preventing tight packing
• acts as a buffer

Question 14

peripheral proteins

Answer 14

bound to surface of the membrane

Question 15

integral proteins

Answer 15

penetrate hydrophobic core

Question 16

transmembrane proteins

Answer 16

integral proteins that span the membrane

Question 17

Functions of membrane proteins

Answer 17

transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix

Question 18

transport proteins

Answer 18

allow passage of hydrophilic substances across membrane

Question 19

aquaporines

Answer 19

channel proteins that facilitate passage of water molecules

Question 20

carrier proteins

Answer 20

a type of transport protein, binds to molecules and changes shape to shuttle across membrane
-specific for substances to move