Chapter 1: The Biochemical Basis of Life

Question 1

Ionic bonds

Answer 1

once atom takes an electron from another (metal and non-metal)

Question 2

Covalent bonds

Answer 2

two atoms share electrons (non-metal and nonmetal)

Question 3

Hydrogen bond

Answer 3

hydrogen forms a bond with N,O or F

Question 4

Glycosidic linkage/glycosyl bond

Carbs

Answer 4

is what holds monosaccharides together

• If the hydroxide on carbon one is on the top it is BETA, if it is on the bottom it is ALPHA
• Monosaccharides are isomers meaning they have the same elements but different composition

Question 5

Peptide bond

Protein

Answer 5

During the synthesis of peptides (multiple amino acids) a dehydration synthesis reaction occurs bonding the amino acids creating a peptide joined by a peptide bond.

Question 6

Phosphodiester bond

Nucliec acids

Answer 6

type of bond that connects the sugar molecules in the backbone of DNA or RNA.

Question 7

ester bond

Lipids

Answer 7

Fats are formed from the joining of glycerol and fatty acids, they are held together by ester linkages which are formed through dehydration synthesis reactions (can be saturated or unsaturated)

type of bond formed when an alcohol group (–OH) reacts with a carboxyl group (–COOH) of a fatty acid

Question 8

Dehydration synthesis (condensation):

Answer 8

• Two molecules combine to form a larger molecule.
• During this process, a water molecule (H₂O) is removed—an OH from one molecule and an H from the other.

Reactant 1 (with -OH) + Reactant 2 (with -H) ——-> Product +
H20

Question 9

Hydrolysis reaction

Answer 9

• A water molecule (H₂O) is used to break apart a large molecule into two smaller ones.
• The OH goes to one piece, and the H goes to the other.

Question 10

Protein structure

primary

Answer 10

The exact order of amino acids in a protein.

With 20 amino acids, a chain of 50 amino acids can have a huge number of different combinations.

Changing just one amino acid might stop the protein from working.

Question 11

Protein structure

Secondary

Answer 11

folds and coils at various locations of polypeptide due to hydrogen bonding in the polypeptide backbone.

Common structures:
- β-pleated sheet - 2 parallel polypeptide chains joined to one another by hydrogen bonds
- α-helix: Hydrogen bonding between every fourth amino acid, creating a coil shape Ex. keratin = fibrous protein in hair

Question 12

Protein structure:

Tertiary

Answer 12

The 3D shape of a protein is determined by interactions between the R-groups in the polypeptide chain.

These interactions include:
- Ionic bonds: Between + and – side chains.
- Hydrogen bonds.
- Hydrophobic interactions: Non-polar side chains stick together.
- Disulfide bridges: Strong covalent bonds formed between two cysteine amino acids (-SH groups join to make S-S bonds).

Together, these forces stabilize the protein’s shape.

Common

Question 13

protein structure

Quaternary

Answer 13

some proteins consist of 2 or more polypeptide chains aggregated into one functional macromolecule

• E.g., Collagen has strong fibres found in bones, tendons, ligaments, skin
• E.g., Hemoglobin consists of 2 types of polypeptide chains (2 α, 2 β);

Question 14

activation energy

Answer 14

• all chemical reactions require energy in order to take place.
• this energy is called activation energy (Ea)
• enzymes (catalysts) work by lowering the activation energy of chemical reactions

Question 15

denaturation – what are factors that affect enzyme function?

Answer 15

1. pH:
   * Enzymes work best at certain pH levels. For example, stomach enzymes like gastrin only work at a pH of 2. Changes in pH can stop them from working.
2. Temperature:
   * Enzymes have a specific temperature range where they work best. High temperatures, like during fevers, can damage enzymes.
3. Salt Levels:
   * Too much or too little salt can change the shape of enzymes and stop them from working.
4. Other Conditions:
   * Preservatives or curing meats can denature enzymes in bacteria.
   * Heat from curling or straightening hair can also affect proteins.

Question 16

Enzyme inhibition – define

competitive & non-competitive inhibition

Answer 16

• competitive inhibitors - are similar in structure to the substrate and are able to bind with the active site and block the normal substrate from binding
• noncompetitive inhibitors - do not compete with substrate for the active site
  attach to a different site on the enzyme which changes its shape causing the substrate to not bind properly

Question 17

Enzyme inhibition

allosteric regulation

Answer 17

molecules that bind a part of the active site like non competitive inhibitors, they can enhance or inhibit enzyme activity, they attach on allosteric sites on the enzyme and can increase or decrease an enzyme’s affinity for substrate.