CHAPTER 5 CELL MEMBRANE

DV in lab Enzyme #2 lab

Absorbance

Biologists use the fluid mosaic model to describe membrane structure. Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.

Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. The diverse proteins found in and attached to membranes perform many important functions. The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center.

Controlled variables (all equal) in Enzyme #2 lab

Enzyme extract, Guaiacol, Volume in test tubes

If a red blood cell is places in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

Hypotonic

How can a lipid be distinguished from a sugar?

Lipids are mostly non-polar

How can a lipid be distinguished from a sugar?

Lipids are mostly nonpolar.

What name is given to the process by which water crosses a selectively permeable membrane?

Osmosis

Control treatment in Enzyme #2 lab

Room T

Osmotically active substance

Solutes that cause osmosis are called,

IV in lab Enzyme #2 lab

Temperature

Which of the following factors does not affect membrane permeability?

The polarity of membrane phospholipids.

In facilitated diffusion, what is the role of the transport protein?

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

True

True/False: osmosis is the diffusion of water across a selectively permeable membrane

When molecules move down the concentration gradient it means they're moving them

an area of high concentration to an area of lower concentration

Selective permeability

is a property of cellular membranes that only allows certain molecules to enter or exit the cell

Osmosis

is the net movement of water across a semipermeable membrane from an area of higher solute concentration to an area of lower solute concentration

Isotonic

nothing happens to the cell because water moves into the cell at the same rate that it moves out of the cell.

Solute

part of a solution present in a smallest amount

Osmolarity

the concentration of solute particles in the solution, regardless of the type of particle. If two solutions have equal osmolarity, then they have equal water concentrations.

Osmotic pressure

the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis, often used to express the concentration of the solution.

Concentration gradient

the process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles.

The permeability of a biological membrane to a specific polar solute may depend on which of the following?

the types of transport proteins in the membrane

Hypotonic

water will flow into the cell, causing it to swell (and possibly burst).

Hypertonic

water will flow out of the cell, causing it to shrink.