Biology (Passive transport)

Homeostasis

Maintaining a constant internal environment despite external conditions

Kinetic molecular theory

All matter is made of particles
particles are always in motion
heat energy speeds up motion of particles

Concentration gradient

Difference in concentration of solute between 2 areas

Brownian motion

random movement and collision of molecules in solution or gas allow diffusion to occur

Solute vs solvent

Solute - thing being dissolved
Solvent - thing doing the dissolving

Passive transport

the movement of a substance across the cell membrane without using energy

How does a substance always travel

Along the concentration gradient

Types of Passive transport

Simple diffusion - No proteins
Facilitated diffusion - With proteins

Simple Diffusion

No energy or proteins required
small nonpolar molecules pass well

Osmosis

The diffusion of water across a selectively permeable membrane
No energy required
Only in small amounts without proteins

Facilitated diffusion

No energy needed
Protein aid in diffusion

Channel protiens

Hydrophobic interior
Transports many nonpolar molecules over

Carrier proteins

Binds to specific solute and changes shape

Aquaporins

Channels specifically for water

Isotonic solution

Concentration of solute inside is equal to outside
No net change in water movement
Animal cells - RBC is disk shaped
Plant cells - Turgor pressure to some extent

Net change

overall difference between starting and ending amount

Hypotonic solution

High concentration of solvent than solute
Water moves into cell
Animal cell - cytolysis, bursting of water due to increased osmotic pressure
Plant cell - Turgid, high turgor pressure, gives crisp feeling from plants

Hypertonic solution

Greater concentration of solute than solvent
Water moves out of cell
Animal cells - Crenation, shrivels due to drop of osmotic pressure
Plant cells - Plasmolysis, loss of turgor pressure

What affects rate of diffusion

concentration difference

dynamic equilibrium

The state in which no net movement but molecules still moving

What are 2 major factors that affect difficulty to move across membrane

Size and charge

Why does water move in and out of a cell and not salt?

Water usually moves more because aquaporins let huge numbers of water molecules pass quickly, while salt ions can only move slowly through specific ion channels that tightly control them

Explain molecules moving from high to low

The process of moving from high to low concentration is called diffusion and it occurs because of brownian motion, which states that molecules are constantly in motion and like to spread out evenly due to random movement and collisions