Lab 4 Transport Mechs

Active Transport

The movement of molecules across a membrane from a region of lower concentration to a region of higher concentration, requiring energy (ATP).

Passive Transport

The movement of molecules across a membrane without the need for energy, typically from an area of higher concentration to an area of lower concentration.

Diffusion

The process by which molecules spread from areas of high concentration to areas of low concentration.

Osmosis

The movement of water molecules across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Iso-osmotic

A solution that has the same osmotic pressure as another solution.

Hyper-osmotic

A solution that has a higher osmotic pressure (concentration of solute) than another solution.

Hypo-osmotic

A solution that has a lower osmotic pressure (concentration of solute) than another solution.

Facilitated Diffusion

A type of passive transport that allows substances to cross membranes with the assistance of special proteins.

Exocytosis

The process by which a cell expels materials in a vesicle that fuses with the plasma membrane.

Endocytosis

The process by which a cell takes in materials by engulfing them in a vesicle.

Aquaporins

Channel proteins in the cell membrane that facilitate the transport of water between cells.

Vesicular Transport

Transport of materials inside vesicles, encompassing processes like exocytosis and endocytosis.

Concentration Gradient

The difference in the concentration of a substance between two areas.

Hydrophilic

Having an affinity for water; able to dissolve in water.

Hydrophobic

Having little or no affinity for water; repelling water.

Semipermeable membrane

A membrane that allows certain molecules or ions to pass through by diffusion and occasionally by more specialized processes.

Tonicity

The ability of a solution to cause a cell to gain or lose water, affecting the cell’s volume.

What was the main objective of the egg experiment?

To demonstrate the effects of osmosis on the egg in different solutions.

What materials were used in the egg experiment?

A raw egg, vinegar, corn syrup, and distilled water.

What happens to the egg when placed in vinegar?

The eggshell dissolves, leaving behind the semi-permeable membrane.

What is the role of the vinegar in the experiment?

Vinegar creates an acidic environment that dissolves the calcium carbonate structure of the eggshell.

What occurs when the egg is placed in corn syrup?

Water moves out of the egg due to osmosis, causing the egg to shrivel.

What happens to the egg when placed in distilled water?

Water enters the egg, causing it to swell due to osmosis.

What is the purpose of measuring the mass of the egg before and after each solution?

To quantify the changes in the egg's mass due to osmosis.

How did the size of the egg change in the corn syrup?

The egg decreased in size as water exited the egg into the hypertonic corn syrup.

What is osmotic pressure?

The pressure that must be applied to prevent water from moving across the membrane due to osmosis.

What conclusion can be drawn from the egg experiment?

Osmosis occurs when water moves across a semi-permeable membrane from areas of low solute concentration to high solute concentration.

Glucose, Amino Acids

Size: Small; Polarity: Polar; Requires transport proteins to cross the plasma membrane.

Water (H2O), Charged Ions

Size: Small; Polarity: Polar; Moves across the plasma membrane via aquaporins, a type of transport protein.