Biology - Diffusion&Osmosis_ch 5

When studying with a friend for a test, what key points about osmosis would you make sure you tell them? Check all that apply.

*Osmosis refers to the movement of water along a concentration gradient. *If osmosis occurs across a membrane, then diffusion is not occurring.

Facilitated Diffusion

Cell by diffusion through specific channel proteins or carrier protein embedded in the plasma membrane, provided there is a higher concentration of the moelcule outside the cell than inside

Determine if each statement applies to facilitated diffusion, active transport, or both.

Facilitated diffusion - Molecules move down their concentration gradient. Active transport - Molecules move against their concentration gradient. Requires energy (ATP). Both - Carriers are specific for the structures for individual molecules. Molecules move through a protein carrier in the membrane.

Glucose is taken up by red blood cells by binding to a specific pocket in a membrane protein that then allows it to cross the membrane and move down its concentration gradient. What would be the best explanation of this process?

Facilitated diffusion using a transporter

Cells are placed in a solution of glucose. The rate at which glucose enters the cells increases as the concentration of the glucose solution is increased. Eventually the rate of glucose movement stops increasing. How is glucose moving into cells?

Facilitated diffusion via a carrier protein.

When taking oral medications, several lipid cell membrane barriers have to be passed before the hydrophilic drug can reach circulation. What is the most likely method of transport mechanism the drug would use to cross membranes?

Facilitated diffusion.

Match the properties described with one of the four components of a membrane. Phospholipid bilayer

Forms a semipermeable barrier. Can allow diffusion of gases.

Match the properties described with one of the four components of a membrane. Interoir Protein Network

Helps determine the overall shape of a cell.

Match the properties described with one of the four components of a membrane. Cell Surface Marker

Often carbohydrate attached to a lipid or protein.

Rate of diffusion is affected by different factors. Predict which scenario would have the fastest rate of diffusion.

Small molecules that are highly concentrated in warm temperatures.

Active Transport

Substances are transported from a lower concentration to a higher concentration working against the concentration gradient. This type requires the addition of energy ATP.

Why does a human red blood cell lyse when placed in a hypotonic solution while a plant cell does not?

The cell wall of the plant prevents the membrane from swelling too much. (p105)

After hand washing your clothes, your fingers appear wrinkled because they've taken in water. What is the most plausible explanation?

Your skin is hypertonic to the water.

Concentration Gradient

a difference between the concentration on the inside of the membrane and that on the outside

In osmosis, water molecules move across membranes through aquaporins from

an area of high water concentration to an area of lower water concentration.

The epidermis (top layer of skin) does not have a blood supply. Nutrients reach the epidermis

by diffusing through the tissue fluid from blood vessels in the dermis.

When you breathe, oxygen moves from your lungs into your blood and then into tissues. To do this, oxygen moves across membranes by ______ and from ______ concentration of oxygen.

diffusion, higher to lower

Channel Protein

hydrophilic interior that provides an aqueous channel through which polar molecules can pass when the channel is open

Sea water is approximately 3% salt. If sea water is hypertonic to tissues of freshwater fish you can conclude their tissues contain

less than 3% salt.

Phospholipids

lipid layer that forms the foundation of a cell's membranes us a bilayer formed of these

Simple diffusion is defined as the movement of

molecules from areas of higher concentration to areas of lower concentration.

Phospholipid Bilayer

provides flexiable matric and imposes a barrier

Diffusion

random motion causing a net movement of these substance from regions of high concentration to region of a lower concentration

Solute

salt, is the substance being dissolved.

Isotonic

same osmotic concentration

Hypertonic

solution with higher concentration

Hypotonic

solution with lower concentration

Passive Transport

some ions and molecules through the membrane fairly easily and do so because of a concentration gradient

Facilitated diffusion is used to transport

sugars and amino acids.

Transdermal drug patches, such as nicotine patches, are applied to the skin. The drug is applied in a relatively high dosage to the inside of the patch, which is worn on the skin for periods of time. The drugs enter the bloodstream directly through the skin. Theoretically, how do the patches work?

the drug will move into the blood, through diffusion, for a long period of time, maintaining a constant concentration of drug in the blood

The processes of active transport and facilitated diffusion both

use transport proteins to move material across the membranes.

Solvent

water, Does the dissolving

In the process of diffusion, when sugar is mixed with water, equilibrium would be reached

when the dissolved sugar molecules are evenly distributed throughout the solution.

An experiment involves 4 beakers of fluid containing bags with different solutions. Beaker 1 contains a 0.2M solution with a 0.2M solution bag. Beaker 2 has a 0.2M solution with a 1M solution bag. Beaker 3 holds a 0.2M solution with a 0.4M solution bag. Beaker 4 contains a 0.2M solution with a 0.1M solution bag. Predict which beaker will contain a bag with the largest change in mass after 30 minutes.

Beaker 2 - has a 0.2M solution with a 1M solution bag

Match the properties described with one of the four components of a membrane. Transmembrane protein

Can span both layers of a membrane. Can form channels to allow small molecules to cross membranes.

A cell using protein-mediated facilitated diffusion is treated with a toxin that prevents conformation change in the membrane protein. What is the most likely outcome?

Carrier protein dysfunction will increase the gradient.

Osmosis

Diffusion of water across a membrane toward a higher solute concentration