Fundamentals of Biochem III

Question 1

What is an acid?

Answer 1

• Acids are compounds that ionize in water to form H+ ions
• They have a pH of less than 7
• They are proton (H+) donors

Question 2

What is a base?

Answer 2

• Compounds that ionize in water to form OH- ions
• They have a pH of more than 7
• They are proton (H+) acceptors

Question 3

What is a neutralization reaction?

Answer 3

• Reactions where acids and bases react to form water and salt molecules

Question 4

How can the pH of solutions be found?

Answer 4

• Experimentally
• Can be calculated

Question 5

Experimentally

Answer 5

Using:
- pH paper
- litmus paper
- liquid indicators (phenolphthalein or bromothymol blue)

Question 6

What are buffers?

Answer 6

• Chemical substances that are able to equalize the acidity or basicity of aqueous solutions

Question 7

Why are buffers important in living organisms?

Answer 7

Because they tend to maintain steady pH’s in blood and tissues

Question 8

What is the autoionization of water?

Answer 8

• H2O molecules react with each other since water is technically both hydrogen ions and hydroxide ions mixed together

Question 9

What is the chemical equation of the autoionization of water?

Answer 9

H2O + H2O ↔ H3O+ + OH-

Question 10

What are strong acids and bases?

Answer 10

• When acids or bases ionize completely/dissociate in water
• They are rare in biological systems

Question 11

Example of a strong acid?

Answer 11

hydrochloric acid (HCl)

Question 12

Example of a strong base?

Answer 12

Sodium hydroxide (NaOH)

Question 13

What are weak acids and bases?

Answer 13

• They are only able to ionize partially in water
• Since ionization is partial, the reaction is reversible
• Weak acids and bases are in a state of equilibrium

Question 14

Example of a weak acid?

Answer 14

Acetic acid (vinegar) CH3COOH

Question 15

Example of a weak base?

Answer 15

Ammonia NH3

Question 16

What are conjugate acids?

Answer 16

• The acid formed by adding a proton to a base

Question 17

What are conjugate bases?

Answer 17

• The base formed by removing a proton from an acid

Question 18

What are conjugate acid/base pairs?

Answer 18

• Same overall chemical structure, but different ionic charges

Question 19

How do living cells and tissues keep the body’s pH neutral?

Answer 19

• They use buffers to resist severe changes in the pH of blood, body fluids or tissues

Question 20

What is the best example of an acid-base buffer system in living organisms?

Answer 20

The Carbonic acid/bicarbonate Buffer System
- It is a blood buffer system,

Question 21

Carbonic acid/bicarbonate Buffer system chemical equation

Answer 21

H2O + CO2 ↔ H2CO3 ↔ HCO3- + H+

Question 22

Blood buffer system equation in words

Answer 22

Water + Carbon Dioxide ↔ Carbonic Acid ↔ Bicarbonate ion + Hydrogen ion

Question 23

Blood buffer system - H2O

Answer 23

• Ingested, or a by product of cell respiration
• Excess amounts are urinated out

Question 24

Blood buffer system - CO2

Answer 24

• Created as a byproduct of cell respiration
• Excess amounts are exhaled to counteract an acidic environment

Question 25

Blood buffer system - H2CO3

Answer 25

- Intermediate point - Found in low levels in all tissues

Question 26

Blood buffer system - HCO3-

Answer 26

- When this accmulates in high amounts, the kidneys relase more into the urine

Question 27

Blood buffer system - H+

Answer 27

- Accumulation of this makes the system acidic - Acidity is counteracted by urinating H+ ions

Question 28

If body tissues become acidic...

Answer 28

- equation moves towards the left to make more water and CO2 to increase basicity - These are removed through breath and urine

Question 29

If body tissues become basic...

Answer 29

- equation moves towards the right to make more free H+ ions to increase acidity - These can be removed through urine if too high

Question 30

Body's blood pH range

Answer 30

7.35-7.45

Question 31

Acidosis

Answer 31

- pH drops below 7.35 - Occurs when system is too acidic - is an extreme condition

Question 32

Alkalosis

Answer 32

- pH rises above 7.45 - Occurs when system is too basic - is an extreme condition

Question 33

Acedimia

Answer 33

- pH drops below 7.35 - Occurs when system is too acidic - Minor condition

Question 34

Alkalemia

Answer 34

- pH rises above 7.45 - Occurs when system is too basic - Minor condition