Lecture 6

Question 1

Osmosis

Answer 1

Diffusion of water across a permeable membrane

Question 2

Tonicity

Answer 2

Ability of a surrounding solution to cause a cell to gain or lose water

Question 3

Isotonic Solution

Answer 3

Solution with the same solute concentration as another solution
Results in no net movement of water across plasma membrane.

Question 4

Hypotonic

Answer 4

When a solution has a lower concentration than another solution in a cell
Results in solute flowing into cell towards higher concentration

Question 5

Hypertonic

Answer 5

When a solution has a higher concentration than another solution in a cell
Results in solute flowing out of cell towards higher concentration

Question 6

Passive Transport

Answer 6

Requires no energy
Substances move down concentration (high to low) gradient
Hydrophilic, charged ions, and larger molecules
Two Types:
- Diffusion - Passive transport that doesn’t require proteins to shuttle a substance. Usually involves a nonpolar molecule
- Facilitated Diffusion - Passive transport that requires proteins to shuttle a substance

Question 7

Active Transport

Answer 7

Requires an input of energy (mostly generated by ATP)
Involves the transport of proteins
Moves substances against concentration gradient
Can stimulate co-transport, when a substance going down its gradient stimulates another to go down its gradient
ex: Na+/K+ Pump which transports 3 sodium out and 2 potassium in

Question 8

Bulk/Vesicular Transport (Exocytosis)

Answer 8

Cell secretes certain molecules by a fusion of vesicles and plasma membrane

Question 9

Bulk/Vesicular Transport (Endocytosis)

Answer 9

Cells takes in molecules and particulate matter by forming new vesicles from the plasma membrane
Resembles reverse exocytosis
Steps:
1. Small area of plasma membrane sinks inward to form pocket
2. As pocket deepens, it pinches in, forming a new vesicle containing material from outside the cell