U1L7: Biochemical Interactions

Question 1

What is the formula for a neutralization rxn?

Answer 1

Acid + Base —> Salt + Water

Question 2

Many reactions in the body occur in pH ranges of…

Answer 2

7.35 - 7.45

Question 3

What is Acidosis?

Answer 3

when blood pH falls between 7.1 – 7.3 (can result in vomiting, brain damage, kidney disease)

Question 4

What is Alkalosis?

Answer 4

when blood pH increases to 7.5 (can result in dizziness, fatigue)

Question 5

What are buffers?

Answer 5

To maintain pH ranges, organisms rely on buffers (substances that resist changes in pH by releasing H+ ions when a fluid is too basic, or by taking in H+ ions when a fluid is too acidic).

Question 6

Explain the Carbonic Acid-Bicarbonate Buffer System

Answer 6

CO2 (product of respiration) is dissolved in blood and taken up by red blood cells and converted to carbonic acid (H2CO3) by carbonic anhydrase enzyme. Most of the carbonic acid then dissociates to bicarbonate and hydrogen ions.

Question 7

Explain what happens if the blood becomes to acidic?

Answer 7

Excess H+ ions in blood will react with HCO3- ions to produce carbonic acid (H2CO3), which dissociates into CO2 and water.

Question 8

Explain what happens if the blood becomes to basic?

Answer 8

Excess CO2 in blood will react with H2O to produce carbonic acid (H2CO3), which dissociates into H+ and HCO3- to decrease the pH of the blood.

Question 9

What are Oxidation-Reduction Reactions?

Answer 9

They are rxns that involve the transfer of electrons - provide cellular energy. When a molecule loses electrons (or H atoms), it becomes oxidized, when a molecule gains electrons (or H atoms), it becomes reduced.

Question 10

Explain how Dehydration (condensation) & Hydrolysis Reactions occur

Answer 10

When an H atom is removed from one functional group, and an OH is removed from another functional group, resulting in the formation of an H2O molecule. This occurs in the assembly of all of the macromolecules.

• Dehydration Rxn: a rxn that involves the removal of an H2O molecule
• Hydrolysis Rxn: a rxn that requires an H2O molecule to break apart a larger molecule

Question 11

Explain howEnzyme Catalyzed Reactions work

Answer 11

Provide alternative pathway of lower activation energy, thus speeding up the rate of the reaction. Do not undergo permanent change during the reaction, therefore they can be reused. Very specific to reactions and substrates

• Specificity is due to complementary shape, hydrophobic/hydrophylic characteristics (and charge).

Question 12

What are active sites?

Answer 12

Recall that enzymes are proteins (made of amino acids). There are indentations on their surfaces called active sites which have a unique shape that interacts with the reactant (substrate). The substrate joins with the enzyme to form an enzyme-substrate complex.

Question 13

What are Allosteric sites?

Answer 13

sites distant from the active site that contain receptors

Question 14

What is an example of Allosteric Activator?

Answer 14

An example of this occurs when oxygen binds to hemoglobin. The binding of oxygen to one subunit induces a change in that subunit that interacts with the remaining active sites to enhance their oxygen affinity.

Question 15

Explain Competitive and Noncompetitive Inhibitors

Answer 15

Some substances inhibit the action by the enzyme (poisons and drugs). Competitive inhibitors bind to the active site of the enzyme.

Question 16

Examples of Competitive Inhibitors

Answer 16

Cyanide: Cyanide acts as competitive inhibitor to the enzyme cytochrome c oxidase. This prevents the electron transport chain (the last part of cellular respiration) from working, meaning that the cell can no longer produce ATP for energy. A cyanide is any chemical compound that consists of a carbon atom triple bonded to a nitrogen atom.

Question 17

Explain what Allosteric/non-competitive inhibitors are

Answer 17

Noncompetitive inhibitors bind to allosteric sites. This type of inhibition results in a change in structure and shape of the enzyme.

Question 18

What is an example of Allosteric/non-competitive inhibitors?

Answer 18

Penicillin: Penicillin acts by binding to the bacterial enzyme DD-transpeptidase. The bacteria uses this enzyme to catalyze the formation of peptidoglycan cross-links in its cell wall. Without this enzyme it can no longer make new cross-links, all the while continuing to make enzymes that hydrolyze (break-down) these links. This will cause holes in the cell wall to form and eventually force the bacteria to shed most if not all of its wall.

Question 19

What is an Allosteric site?

Answer 19

It is a binding site on an enzyme where regulatory molecules bind to stimulate OR inhibit enzyme activity

Question 20

What is a Allosteric activator?

Answer 20

It stabilizes enzyme shape so active site has high affinity for substrate.

Question 21

What is a Allosteric inhibitor?

Answer 21

It stabilizes inactive form of enzyme so substrate is released.

Question 22

What are the Factors that Affect the Rate of Enzyme Activity?

Answer 22

• Presence of cofactors (metal ions) and coenzymes (specific helper molecules req’d for enzyme function)
• pH
• Temperature
• Concentration of substrate
• Concentration of inhibitors
• Concentration of enzymes (active sites)

Question 23

Explain “activator”

Answer 23

An activator binds to an allosteric site, the shape of the enzyme changes so that the active site is available to substrate.