BMED- The Cellular Level of Organization

Plasma Membrane is…

Selectively Permeable

Selectively permeability restricts materials based on…

1. Size

2. Electrical Charge

3. Molecular Shape

4. Lipid Solubility

• What are the two ways that transport happens in the plasma membrane?

• Active Transport- Energy Required

• Passive Transport- No Energy Required

All molecules are constantly in…

Motion

Molecules in a solution move…

Randomly

What is concentration?

The amount of solute in a solvent

What is concentration gradient?

When more solute is on one part of the solvent than the other

Diffusion is a function of the…

Concentration gradient

What happens during diffusion?

• Molecules mix randomly

• Solute spreads through solvent

• Concentration gradient is eliminated

• Solutes move down a concentration gradient

• What are the main 5 factors that affect diffusion?

• Distance the particles has to move in

• Molecule size (Smaller is faster)

• Temperature (More heat, faster motion)

• Gradient Size (The difference between high and low concentration)

• Electrical Charges (Opposites attract)

Materials that diffuse by simple diffusion?

• Lipid-soluble compounds (alcohols, fatty acids, and steroids)

• Dissolved gases. (Oxygen and Carbon Dioxide)

Materials that pass through transmembrane proteins?

• Water soluble compounds

• Ions

What is osmosis?

The diffusion of water across the cell membrane

More solutes in water, _____ concentration of water

Lower

Membrane must be _____ permeable to water , _______ permeable to solutes

Freely, Selectively

Water molecules diffuse across membrane _____ solution with ____ solutes

Toward, more

What is osmotic pressure?

The force of a concentration gradient of water and equals the force needed to block osmosis

Two fluids may have the same _____, but different ______

Osmolarity, Tonicity

What is isotonic?

A solution that does not cause osmotic flow in or out of the cell, stable

What is Hypotonic ?

A solution has a lower solute concentration than the cell causing water to move into the cell

What is Hypertonic?

A solution has a higher solute concentration than the cell, causing water to move out of the cell

How are osmolarity and tonicity related ?

Both compare the solute concentration of two solutions separated by a membrane

What makes osmolarity and tonicity different?

Osmolarity takes into account the total concentration of penetrating solutes and non-penetrating solutes, whereas tonicity takes into account the total concentration of only non-penetrating solutes

A cell in hypotonic solutions…

• Gains water

• Ruptures (Hemolysis of red blood cells)

A cell in a hypertonic solution…

• Loses water

• Shrinks (Crenation of red blood cells)

What is carrier mediated transport?

• Transports ions and organic substrates

• Facilitated diffusion

• Active transport

• Specificity- one transport protein, one set of substrates

• Saturation Limits- rate depends on transport proteins, not substrate

• Regulation- cofactors such as hormones

What is contransport?

Two substances move in the same direction at the same time

What is counter transport?

One such stance moves in while another moves out

What is uniport?

Movement of one substance in one direction

What is symport?

Movement of two molecules in the same direction

What is antiport?

Movement of two molecules in opposite directions

What is facilitated transport?

• Passive

• Carrier proteins helps transport molecules too large to fit through channel proteins

How do carrier proteins work?

• Molecule binds to receptor site on carrier protein

• Protein changes shape, molecules pass through

• Receptor site is specific to certain molecules

What is active transport?

• Move substrate against concentration gradient

• Requires energy such as ATP

• ion pumps move ions

What does an exchange pump do?

Countertransports twi ions at the same time

Characteristics of sodium-potassium pump

• Active transport

• Carrier mediated

• Sodium out, potassium in

• 1 ATP moves 3 Na and 2 K

What does Na+/K+-ATPase help with?

• Maintains resting potential

• Avail transport

• Regulate cellular volume

What happens during secondary active transport?

• Na+ concentration gradient drives glucose transport

• ATP energy pumps Na+ back out

What is the difference between first and second active transport?

The source of energy. In primary active transport, the carrier protein uses energy directly from ATP through hydrolysis. In secondary active transport it uses energy stored in the concentration gradients of ions

What is vesicular transport?

Materials moving in or out of cells in vesicles

What is endocytosis?

• Inside

• Uses ATP

• 3 Main Types

  • Receptor mediated endocytosis

  • Pinocytosis

  • Phagocytosis

What is exocytosis?

• Outside

• Granules or droplets are release from the cell

What happens during receptor mediated endocytosis?

• Receptors (glycoproteins) bind target molecules (ligands)

• Coated vesicles (endosomes) carries ligands and receptors into the cell

What is pinocytosis?

Endosomes drink extracellular fluid

What is phagocytosis?

Engulf large objects in phagosomes

What is exocytosis?

Is the reverse of endocytosis meaning it ejects lathe objects