Chapter 4: Physiology Of Cells

Question 1

What is passive transportation?

Answer 1

The process that moves substances through a membrane that does not require energy.

Question 2

What is diffusion?

Answer 2

The tendency of small particles to spread out and distribute themselves evenly within a given space; from high concentration to lower.

Question 3

What is a concentration gradient?

Answer 3

A measurable difference of solute concentration form one area of a solution to another

Question 4

What is dynamic equilibrium?

Answer 4

The condition in which both sides of a membrane have equal concentrations of a solute.

Question 5

What is simple diffusion?

Answer 5

When molecules or solutes pass directly through a membrane.

Question 6

What is osmosis?

Answer 6

The diffusion of water through a selective permeable membrane to achieve dynamic equilibrium.

Question 7

Define the 3 osmotic pressures as they relate to red blood cells.

Answer 7

Isotonic is when the pressure of a solution and that inside the cell are equal.
Hypotonic is the internal pressure of the cell is HIGHER than that of its environment. The cell will expand.
Hypertonic is when the internal pressure of the cell is LOWER than that of its environment. The cell will collapse.

Question 8

What is facilitated diffusion?

Answer 8

A passive process that occurs when a specific membrane channel and transport protein carry the particles inside the cell.

Question 9

What are the 2 types of facilitated transport and how do they work?

Answer 9

Channel-mediated transport: process by which water molecules, specific ions air other small water-soluble molecules can cross the membrane.
Carrier-mediated transport:
When molecules move in or out of the cell by their concentration gradient by passing through a membrane carrier.

Question 10

Is filtration passive or active?

Answer 10

Passive.

Question 11

What is active transport?

Answer 11

A process that uses energy to push or pull substances across the membrane against its concentration gradient.

Question 12

What are the 2 types of active transport?

Answer 12

Transportation by pump

Transportation by vesicle

Question 13

What are the 4 passive transport processes?

Answer 13

Diffusion
Simple diffusion
Osmosis
Facilitated diffusion

Question 14

How does a sodium-potassium pump work?

Answer 14

3 sodium ions attach to sodium binding site of the pump on the intracellular side of the membrane. Simultaneously, an ATP binds to the pump. When the ATP breaks apart, energy is released and the pump changes shape, pushing the sodium ions out of the cell and attracting 2 potassium ions to their binding site. When the pump returns to its original shape, the potassium is drawn into the cell.

Question 15

What are the 2 different types of “transportation by vesicle”?

Answer 15

Endocytosis

Exocytosis

Question 16

What are the 4 types of endocytosis?

Answer 16

Receptor-mediated
Phagocytosis
Pinocytosis

Question 17

What is endocytosis?

Answer 17

When the membrane “traps” extracellular material and brings it inside the cell

Question 18

Describe receptor-mediated endocytosis.

Answer 18

Special receptor on the plasma membrane bind to specific molecules in the extracellular fluids and brings it inside

Question 19

What is phagocytosis?

Answer 19

“Cell eating”; type of endocytosis that engulfs large particles or microorganisms, forming vesicles around them for the expressed purpose of destroying it.

Question 20

What is pinocytosis?

Answer 20

“Cell drinking”; the endocytosis of liquids and the substance dissolved in it.

Question 21

What is exocytosis?

Answer 21

The process by which large molecules, packaged in vesicles, can leave the cells though they are too big to cross the membrane by other means. Waste and secretions exit the cell in this fashion.

Question 22

What is cellular metabolism?

Answer 22

The sum of all chemical reactions of a cell.

Question 23

What is a metabolic pathway?

Answer 23

The various types of chemical reactions

Question 24

What is catabolism?

Answer 24

The breakdown of molecules; usually resulting in energy

Question 25

What is anabolism?

Answer 25

The building of larger molecules from smaller ones; requires energy.

Question 26

What is an enzyme?

Answer 26

Functional proteins that serve as catalysts to nearly all chemical reactions.

Question 27

What is a catalyst?

Answer 27

They lower the amount of required energy needed to start a chemical reaction.

Question 28

What are the 3 main features of enzyme structure?

Answer 28

• Enzymes are tertiary (3-faces) or quaternary (4-faces) with complex shapes.
• Their molecules often have non-protein part called a co-factor. If the co-factor is an organic, it’s called a coenzyme.
• Enzymes are “lock-and-key”; they a can only work on the molecules type they were created for.

Question 29

How are enzymes named?

Answer 29

Combing the root of the substance they act on and the suffix “-ase”

Question 30

What are the 2 key functions of an enzyme?

Answer 30

• Every reaction that occurs in a metabolic pathway requires one or more enzymes.
• Metabolic pathways can be regulated by activation and inactivation of certain enzymes

Question 31

What can destroy an enzyme’s ability to function?

Answer 31

• An allosteric effector is a molecule or other agent changes the enzyme’s shape.
• Denaturation is when environment factors, like pH or temperature, change the shape

Question 32

What is cell respiration and where does in the cell it take place?

Answer 32

The process by which break down nutrients (carbohydrates, fats, proteins) into carbon dioxide and water. It happens in the mitochondria.

Question 33

Define and explain glycolysis.

Answer 33

“Breaking of glucose”; the catabolic process of breaking down glucose into energy.

• 1 glucose molecule is broken into 2 pyruvic acids.
• If no oxygen is present, the pyruvic acid will continue on an anaerobic pathway(lactic acid)
• If oxygen is present, the pyruvic acid continues on an aerobic pathway (citric acid and electron transport)

Question 34

Describe the citrus acid cycle (Krebs cycle)

Answer 34

• Pyruvic acid (3-carbon) is broken into two 2-carbon molecules (acetyl), giving off one carbon dioxide and energy in the form of electrons that are carried off to the electron transfer system.
• Each acetyl then binds to a 4-carbon (oxaloacetic acid) to form a 6-carbon (citric acid)
• Enzymes then work on each citric acid, releasing two carbon dioxide molecules and energy (either ATP or electrons), creating the original 4-carbons at the beginning of the beginning of the chain.
• The cycle repeats.

Question 35

Describe the electron transport cycle.

Answer 35

• Electrons jump for 1 enzyme to the next, losing a small amount of energy as the go.
• The “lost” energy is used to pump their accompanying proton (H+) out of the inner chamber to the outer chamber of the mitochondria.
• The protons travel down their concentration gradient through ATP synthase and the energy is stored in the bonds of ATP.
• The jumping electrons & their protons are captured by oxygen molecules to form metabolic water.

Question 36

Why is aerobic cellular respiration better for the cells than anaerobic?

Answer 36

In the anaerobic process, the pyruvic acid either converted back to glucose or stays as pyruvic acid. It releases no energy.

The aerobic process creates 36 to 38 ATP molecules from a single glucose molecule.