Laboratory 2: Cell Transport and Cell Permeability

The kinetic energy of all molecules above _________ (approximately -273°C or -459°F) causes those molecules to move or vibrate.

absolute zero

the random movement of microscopic particles suspended in a gas or liquid, caused by the collision of small molecules in the surrounding medium.

Brownian Motion

the diffusion of water across a selectively permeable membrane. The solutes in water do not diffuse during osmosis—only the water diffuses. During osmosis, water follows the law of diffusion and moves from an area of higher concentration of water to an area of lower concentration of water until equally distributed, if possible.

Osmosis

Osmosis is the movement of ___ from a ___ concentration of SOLUTE (less solute, more water) to one of a ___ concentration of SOLUTE (more solute, less water)

water, lower, higher

Osmosis is the movement of ___ from an area of ___ concentration of WATER (more water, less solute) to a ___ concentration of WATER (less water, more solute)

water, higher, lower

the random movement of a substance from an area of greater concentration to one of lesser concentration until it is equally distributed or reaches equilibrium.

Diffusion

How does concentration gradient affect the rate of diffusion?

positively

How does temperature affect the rate of diffusion?

Positively

How does molecular weight effect the rate of diffusion?

Negatively

When cells swell or become turgid, they can exhibit "______," i.e. they rupture.

lysis

When cells dehydrate, they shrink and exhibit "_________," or become flaccid.

Crenation

In a ____________ solution, there are equal amounts of water and solute.

isotonic

If a somatic cell is placed into a container of saltwater (hypertonic solution), would water move "Into" or "Out of" the cell?

Out of

This occurs because the concentration of solutes (like salt) is higher outside the cell compared to inside, leading to a net flow of water out due to osmosis. So water moves from an area of lower solute concentration to an area of higher concentration.

Steps on how you test how temperature affects the rate of diffusion

1. The instructor will fill the beakers and will place one beaker on a hot plate set at a moderate temperature, and the other beaker on the counter at room temperature.

2. One capsule of potassium permanganate will be placed into the center of each beaker.

3. Examine the beakers immediately after setup, and every five minutes thereafter.

4. The beaker on the hotplate will dissolve the capsule faster

Steps on how you test how molecular weight affects the rate of diffusion

1. Obtain a petri plate containing 10ml of 1% agarose with two small openings punched out.

2. Fill one opening with methylene blue solution and one opening with potassium permanganate solution.

3. Every ten minutes for 30 minutes, use a ruler to record the growing diameters of the dye spots and record the data.

How do you calculate rate of change?

To calculate rate of change, divide the amount of change by the amount of time.

Rate = Change / Time

experimental steps on how to test osmosis

1. Take an initial weight of your assigned dialysis bag. Place in dialysis bag into its assigned beaker.

2. At ten-minute intervals, remove the bag from the beaker.

3. Carefully dry off the excess water and weigh each bag.

4. Calculate the overall rate of change for each bag.

How does Brownian motion look like under a microscope?

The particles are vibrating and moving rapidly. They do not appear uniformed.

Warmer temperatures ___ the rate of diffusion

increases

Cooler temperatures ____ the rate of diffusion

decreases

In a petri dish with two solutions, the one with the more molecular weight will grow ___

slower

This is because the concentration of solutes affects osmosis, where water moves from a low solute concentration to a high solute concentration. Solutions with higher solute concentrations will resist water movement, leading to slower growth for the cells in those solutions.

In a petri dish with two solutions, the one with the less molecular weight will grow ___

faster (expand more)

due to the principle of osmosis, where water moves from the area of lower concentration to the area of higher concentration. This means that the solution with lower molecular weight will allow water to move more quickly, promoting faster growth of the bacteria in that solution.

The higher the sucrose concentration the ___ the rate of osmosis

faster

The area of the solution that has the higher solute concentration

Hypertonic

The area of the solution that has the lower solute concentration

Hypotonic

___________ is the ability of a solution to change the tone or shape of cells by altering their internal water volume.

tonicity

water moves from the ___ side of the solution to the ___ side of the solution

Hypotonic, hypertonic

this is because of the law of osmosis, which is the net movement of water across a selectively permeable membrane from an area of lower solute concentration (hypotonic) to an area of higher solute concentration (hypertonic) to equalize the solute concentrations

In the bag experiment how do you tell if the solution has a low concentration gradient

Measure the rate of diffusion of the solute. A low concentration gradient means that the solute will diffuse more slowly.

In the bag experiment how do you tell if the solution is hypotonic

If the number increases that means the solution was hypotonic, so the bag will gain more weight because water moves from an area of lower solute concentration to an area of higher solute concentration (from the beaker to the bag)

In the bag experiment how do you tell if the solution is hypertonic

if the number decreases that means the solution was hypertonic, so the bag will lose weight because water moves from an area of lower solute concentration to an area of higher solute concentration. (from the bag to the beaker)