Chapter 6 Study Guide

Question 1

Solution

Answer 1

Consists of two or more compounds

Question 2

Solvent:

Answer 2

Compound in the greatest amount. In Biology this is water.

Question 3

Solute:

Answer 3

Present in lesser amounts; dissolves in salts and proteins.

Question 4

What does the term “concentration gradient” mean?

Answer 4

Concentration gradient is the difference between two regions of a solution.

Question 5

What is the definition I gave you for “diffusion”? What is its major property?

Answer 5

Diffusion is random thermal motion of a particle (ion, molecule). The major property is that Diffusion moves from a higher concentration to a lower concentration (net diffusion). Pg. 134

Question 6

What properties must a molecule have if it is to move easily through a plasma membrane?

Answer 6

Most large polar molecules need a carrier protein or an charged ion to get through a plasma membrane. Ions channels permit passage of charged ions. Pg. 135

Question 7

What molecule is generally considered to be an exception to the rule in 4 (re properties a molecule must have to move through
the pm)?

Answer 7

non-polar molecules such as O2, small molecules that have polar covalent bonds CO2, and H2O.

Question 8

What does “permeability” refer to?

Answer 8

Permeability refers to the measure of the ease to which something can move across the membrane.

Question 9

What is the definition for “osmosis”?

Answer 9

Osmosis is the diffusion of water across a membrane according to its own concentration gradient, from high concentration to a lower concentration.

Question 10

What two methods does the textbook mention as ways for molecules, which cannot move through the plasma membrane on their own, to get across the membrane? Pg. 133

Answer 10

Passive transportation: does not require additional energy to move the molecules, and includes simple diffusion, osmosis, and facilitated diffusion. It is the net movement of molecules and ion across a membrane from a higher concentration to a lower concentration (down the concentration gradient).
Active transportation: requires energy to move across the membrane. It moves against the concentration gradient, which means it moves from the lower concentration to the higher concentration. Active Transportation requires the expenditure of metabolic energy (ATP) and involves specific carrier proteins.

Question 11

Why are ion channels often called “gates”?

Answer 11

Because ion channels have structures which open and close like gates to let molecules through. Pg. 135

Question 12

What is the definition I gave for “osmotic pressure”?

Answer 12

Osmotic pressure is the pulling power of a solution has to draw H2O, it is a sucking or drawing pressure.

Question 13

What is “molarity”? What are its units?

Answer 13

Units = M, m

Molarity is the ratio of solute to water.

Question 14

What is:” one gram molecular weight” of anything”? What is it for glucose? NaCl? Sucrose?

Answer 14

One gram molecular weight of anything is equal to 1 mole.
Glucose is 180
NaCl is 58.5
Sucrose is 342

Question 15

What is: 1 mole? How many particles are there in 1 mole? This is known as __________’s #.

Answer 15

One mole of anything is equal to 6.02 x 1023 particles (Avogrado’s Law). This is known as Avogrado’s number.

Question 16

What is the formula (Equation) for figuring out the molarity of a solution? Pg. 137-38

Answer 16

1. Calculate the molecular weight of the solute (e.g. Maltose – 342, NaCl 58.5)
2. Calculate the volume of a solution in liters.
3. 1 mole is equal to (gram-mol weight).
4. 1 mole of anything contains 6.02 x 1023 particles (Avogrado’s Law)
5. 1 mole per liter of a solution = 1M (e.g. 500ml / 2 = ½ Liter)

Question 17

What is “osmolarity”? What are its units?

Answer 17

Osmolarity is the concentration of a solution and its influence in osmolity. It is the tendancy for H2O to move osmality. (Osm) or (osmols)

Question 18

What is the osmolarity of a 2M solution of NaCl? (See notes)

Answer 18

Osmalarity = Mx # of particles of dissociation (osmols)

6.02 x 1023 particles 2 Na+ + 6.02 x 1023 particles 2 Cl- = 24.08

Question 19

What is the molarity of our body fluids? Our osmolarity? (Be sure to include the units)

Answer 19

The molarity of our body fluids is 0.15M (very dilute). The osmolarity of our body is 0.03 osmols (0.15 x 2)

Question 20

What does the term “tonicity” refer to? Pg. 139

Answer 20

Tonicity refers to the tension & pressure of a solution, this is an older term.

Question 21

What do the terms “isosmotic” and “isotonic” mean?

Answer 21

“Iso = equal”  
Isomotic = equal osmotic pressure as the plasma
Isotonic = equal tension and the plasma

Question 22

In the medical world, isotonic refers to a specific osmolarity which is _________

Answer 22

In the medical world, isotonic refers to a specific osmolarity which is the same as the fluids in our bodies.

Question 23

How would you make up an isotonic solution of NaCl? Of Glucose?

Answer 23

???

Question 24

Be able to explain the whole homeostatic process of ”Regulation of Blood Osmolarity”.

Answer 24

1. Increased plasma osmolaity stimulates osmoreceptores in the hypothalamus of the brain
2. The osmoreceptors in the hypothalamus then stimulate a tract of axons that terminate in the posterior pituitary; this causes the posterior pituitary to reslease ADH (Antiduiretic Hormone), in the blood.
3. ADH acts on the kidneys to promote water retention so that a lower volume of more concentrated unrine is excreted.

Question 25

How are large molecules like glucose able to get across the lipid barrier of the plasma membrane? Pg: 141

Answer 25

Large molecules like glucose are able to get across the plasma membranes because of special protein carriers within the membrane. There are two types, Passive and Active Transport.

Question 26

List the 3 properties of “carrier-mediated transport” Pg: 141

Answer 26

Three properties of carrier-mediated transport include: specificity, competition, and saturation (transport maximum (Tm)).

Question 27

Be able to describe the process of “Facilitated Diffusion”. Is it “passive” or “active”?

Answer 27

Facilitated Diffusion is the most common way glucose is transported into the cells, and is helped/aided from transport from the higher concentration to the lower concentration. It is both because ATP is not required.

Question 28

What are GLUT transporters? What variety is found in skeletal muscle?

Answer 28

GLUT transporters are transport carries for the facilitative diffusion of glucose. GLUT4 are found in skeletal muscles. This is a form of passive transportation because glucose is always transported down the concentration gradient. However, in the epithal cells of the kidneys and small intestine this process is considered a form of active transportation because glucose is going against the gradient.

Question 29

Be able to give the characteristics of “active transport”

Answer 29

Active transport requires energy (pump) to from the lower to higher concentrations. There are two types:
Primary: Uses ATP as the source of energy, moves solutes against its concentraton gradient (e.g. going uphill). These carries are often referred to as pumps, most important carriers are Na/K pump
Secondary: Uses another source of engery other than ATP, two types: Cotrannsport (symport) in which the molecules Is moved in the same direction of Na, and Countertransport (antiport) is the molecue or ion being move in the oppositie direction (out of the cell).

Question 30

Is calcium ion in greater amounts inside or outside cells? By what amount is the difference? PG 143

Answer 30

Calcium is greater on extracellarly. Intracellular concentration is 1,000 to 10,000 times lower than the extracelluar concentration.

Question 31

What is the most common 1 (degree) active transport system found in cells? How does this system work?

Answer 31

Na+/ K+ pump

Question 32

These Active Transport systems are often referred to as ________s. Why?

Answer 32

Because the na k pump moves against the concentration gradient.

Question 33

What are the 2 types of 2(degree) active transport? What is their source of energy? Be able to give an example for each.

Answer 33

1. Primary Active Transport (ATP)

2. Secondary Active Transport ( downhill transport of Na+)

Question 34

What does the term “potential” mean as used here? What are the units of these potentials?

Answer 34

Potential means electrical potential because it has the potential to do work. The units are measured in voltage.

Question 35

When a membrane has a “potential”, what is the potential due to? What mechanism caused it?

Answer 35

The membrane has the potential to “do work”. The Na/K pump is the mechanism.

Question 36

What is the electrical charge inside cells? Outside? What is a typical magnitude for a M.P.?

Answer 36

The charge on the inside of the cell is – and the charge on the outside of the cell is +.

Question 37

Explain exactly what: -65mV means.

.

Answer 37

The +/- tells you if the charge is on the inside or the outside of the cell. -65mV means there is 65 milivolts and the charge is on the inside of the cell, the cell is more negatively charged

Question 38

Understand what an “Equilibrium Potential” is and be able to give a definition of it.

Answer 38

This is the “hypothetical” engery. The membrane potential that would result if only 1 ion could move across the membrane. Two forces attract: concentration and electrical.

Question 39

What is the values for: Ek and ENa? What happens if the membrane is at either of these potentials?

Answer 39

Ek = -90mV 
ENa= +66mV

Question 40

What is the significance of the “Nernst Equation”?

Answer 40

Allows you to calculate the equilibrium movement of a potential ion.

Question 41

What are the concentrations of Na and K, both inside and outside the typical cell?

Answer 41

There are typically 3 Na’s and 1 K outside. Inside there are 2 K’s.

Question 42

What is the role of the Na/K pump? What is the ration of Na pumped to K?

Answer 42

The pump acts to counter the Na/K “leaks” and thus maintain the membrane potential. The pump transports 3 Na ions out of the cells for every 2 K ions. This resultes in a constant intracellular concentration of Na/K and a constant membrane potential.

Question 43

By what mechanisms can cells “talk” to one another?

Answer 43

Cell Signaling is how cells talk to one another through gap junctions. They commuicate by chemical messengrs and electrical signals.
Paracrine signaling: considered to be local because it involves the cells of a particular organ. (target cells)
Synaptic: the means by which neurons regulate their target cells. Neurotransmitters are released (chemical regulators)
Endocrine: regulated by Hormones into the extracelluar fluid.

Question 44

Ligand

Answer 44

Any biologically active compound

Question 45

Paracrine

Answer 45

Cells within an organ secrete regulatory molecules that diffuse through the extracellular matrix to nearby target cells. Considered to be local

Question 46

Synaptic

Answer 46

Neurons regulate target cells. They innervate the target organ through a connector called a synapse. Chemical regulators called neurotransmitters are related by axon endings

Question 47

Endocrine

Answer 47

Secrete chemical regulators called hormones. Only target cells for a particular hormone can respond to the hormone.

Question 48

Three G Protiens

Answer 48

Alpha Beta and Gamma. Beta bad Gamma stick together