Bio lab 4 quiz

What is the molecular weight of Cl-

34.45

What is the molecular weight of Br-

79.90

The cell membranes of cells are:

selectively permeable

A membrane that allows all substances below a specific molecular weight to pass through is classified as:

semi-permeable

Dialysis tubing is an example of a:

semi-permeable membrane

Which of the following transport processes do NOT require energy (i.e. are passive transport processes)?

simple diffusion, osmosis, and facilitated diffusion.

Substances moving across the cell membrane by either simple diffusion or osmosis must be:

soluble in the cell membrane.

Hypertonic

solute concentration is higher outside the cell than in. As a result, water will move out of the cell through the process of osmosis, and the cell will shrink.

Isotonic

solution has the same salt concentration as the blood cell. They have the same osmotic pressures so osmosis will not occur

Through active transport, sodium is pumped, against its concentration gradient to:

the outside of the cell.

What component of the cell membrane enables it to maintain a fluid consistency?

unsaturated fatty acids of phospholipids.

Secondary active transport

use of energy in the form of an electrochemical gradient to move a substance into the cell

What is the molecular weight of ferricyanide

329.24

What was the distance between the outer edge of the bromide well and its precipitation band?

.02

What was the distance between the outer edge of the chloride well and its precipitation band?

.03

What was the distance between the outer edge of the AgNO3 well and the precipitation band with Chloride?

.05

What was the distance between the outer edge of the ferricyanide well and its precipitation band?

.05

What was the distance between the outer edge of the AgNO3 well and the precipitation band with bromide?

.07

What was the distance between the outer edge of the AgNO3 well and the precipitation band with ferricyanide?

.07

Calculate the rate of diffusion of Br-.

.3

Calculate the rate of diffusion of Cl.

.6

Calculate the rate of diffusion of ferricyanide.

.7

What was the distance (in cm) between the center well of the agar plate, and each of the three peripheral wells?

1 cm

Substances can move into or out of the cell:

1)If they are soluble in the lipid bilayer, 2)By forming vesicles or vacuoles, or 3)By the action of protein transport molecules in the membrane.

hydrophobic

Are impermeable to ionic and hydrophilic solutes.

What effect does temperature have on rate of diffusion?

Increasing temperature increases rate of diffusion.

What effect do you expect temperature to have on rate of diffusion and why?

Increasing temperature increases the rate of molecular motion, and thus the rate of diffusion.

What effect does molecular weight have on rate of diffusion?

The lower the molecular weight, the more rapid the rate of diffusio

phospholipid bilayer

The phosphate heads are hydrophilic, and are oriented toward the aqueous extracellular environment or the water-based intracellular environmnet. The fatty acid tails are hydrophobic. The tails clump together in the membrane interior through hydrophobic interactions.

Plant cells and bacteria that survive in hypotonic (low solute concentration) environments:

They have a cell wall to prevent their membranes from lysing (rupturing) under these conditions.

Transport Pumps

a form of active transport in which energy in the form of ATP is used to move solutes against their concentration gradients

Osmotic pressure

a measure of the tendency of a solution to take up water

Transport pumps require:

a membrane protein and energy input.

Selectively permeable

a membrane that has elements that allow specific molecules to pass. Cell membranes are selectively permeable. The proteins of the membranes determine what can get into and out of a cell.

Osmosis

a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane. The solution with the higher solute concentration has a lower concentration of water. The process of movement of water across a membrane to dilute a solute concentration is known as osmosis.

The rate of transport of a substance into a cell is drastically reduced when the formation of ATP is blocked. The transport system must be a form of:

active transport

Phospholipids

are amphipathic -- they have hydrophilic phosphate groups and hydrophobic fatty acid groups.

Proteins

are amphipathic -- they have hydrophilic side chains, and hydrophobic side chains.

Constant intracellular conditions

are necessary for enzyme function and cellular system health.

Rank the anions by rate of diffusion (from fastest to slowest):

chloride, bromide, ferricyanide

Based on the fact that rate of diffusion of a molecule is inversely proportional to the square root of molecular weight, which anion should diffuse fastest?

chlorine

fluid mosaic model

describes the structure of the cell membrane. The phopholipids and cholesterol of the phospholipid bilayer are fluid in nature. The mosaic appearance of the membrane is due to the membrane proteins.

Rate of diffusion

directly proportional to the temperature, and inversely proportional to the molecular weight of a molecule.

Binding a molecule to a receptor protein with subsequent formation of an intracellular vesicle is known as:

endocytosis

How is glucose transported into cells?

facilitated diffusion

Dialysis tubing was permeable to albumin.

false

Dialysis tubing was permeable to starch.

false

Pinocytosis

formation of small vessicles that contain extracellular fluids and solutes

amphipathic molecules

have both hydrophobic and hydrophilic regions.

Amoeba and Paramecium, that survive in freshwater, hypotonic environments:

have developed contractile vacuoles to pump water out as it enters the cell by osmosis.

Endocytosis

intake of substances by a cell by forming a vesicle from the plasma membrane. It includes includes pinocytosis, receptor mediated endocytosis, and phagocytosis

Receptor mediated endocytosis

involves a cell membrane receptor that recognizes the particle to be taken into the cell energy-requiring process

Phagocytosis

involves engulfing particulate matter energy-requiring process

cholesterol molecules

is a hydrophobic molecule. It does have a hydroxyl group that is polar. When cholesterol is inserted into the phospholipid bilayer, the hydropholic hydroxyl is oriented toward the membrane exterior. It contributes to the hydrophobicity and fluidity of the membrane interior. It provides a fluid medium through which compounds like proteins can move.

One of the mechanisms for maintaining homeostasis

is the ability for the cell membrane to selectively control what enters and exits

Diffusion

is the process by which a substance moves from a point of higher concentration to a point of lower concentration.

The sodium-potassium pump uses energy to:

move sodium out of the cell against its concentration gradient.

Semi permeable/ selectively permeable

movement of molecules from a point of higher concentration to a point of lower concentration -- a type of passive transport. Will let certain molecules or ions pass through it.

Brownian movement

movement of molecules in solution. Small structures within cells and many bacteria and viruses exhibit Brownian movement, indicating that cells are composed of dynamic molecules that physically and chemically interact with each other.

Impermeable

movement of water down its concentration gradient -- degree of osmosis is dependent on solute concentration and permeability of the membrane. Substances cannot pass through.

Contractile Vacuole

osmoregulatory mechanism in single-celled eukaryotes that survive in hypotonic environments

liposomes

phosholipid bilayer in the form of a lipid droplet or vesicle -- no internal structure.

When phospholipids are put into an aqueous solution they assemble into the following due to hydrophobic interactions.

phospholipid bilayers, liposomes, or micelle

Equilibrium

point at which there is not net change -- in your experiment, equilibrium is the point at which the methylene blue is evenly distributed throughout the vessel.

Integral proteins

proteins stuck to the membrane.

What feature of the cell membrane determines what can pass into and out of cells:

proteins that are present in the membrane.

Exocytosis

substances are released outside of the cell through fusion of a vesicle with the cell membrane.

Facilitated diffusion

takes place when a larger, polar molecule is moved across the membrane. They need a protein carrier to move them across the cell membrane from a region of higher concentration to a region of lower concentration. It is typically higher outside the cell than inside.

Homeostasis

the maintenance of constant internal conditions in an organism

Osmoregulation

the maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations.

Hypotonic

the solute concentration is higher inside the cell than in the exterior environment of the cell. Water will tend to move into the cell through osmosis. The cell can expand to the point that it could burst because of the volume of water.

Diffusion is proportional to

the square root of the reciprocal of the molecular weight of a molecule.

In the experiment using dialysis tubing:

there was a net movement of water into the dialysis tubing.

What was the purpose of the Ag+ in the diffusion in a solid experiment?

to create precipitation bands with the negative ions, enabling measurement of relative rates of diffusion.

Active transport processes include:

transport pumps (movement of solutes across the membrane by transferring a phosphate group to the protein transporter), endocytosis, and exocytosis.

Dialysis tubing was permeable to glucose.

true

Dialysis tubing was permeable to iodine

true