Introduction to biochemistry

Question 1

Describe the three atomic particles.

Answer 1

Proton- Charge 1+ and mass of 1
Neutron- No charge and mass of 1
Electron- Charge 1- and negligible mass

Question 2

How are covalent bonds formed?

Answer 2

By sharing of electrons between atoms.

Question 3

How are orbitals filled?

Answer 3

Electrons fill up orbitals singally, then pair up

Question 4

Order the strength of molecular bonds (Strongest to weakest)

Answer 4

Covalent
Ionic
Hydrogen
Hydrophobic interactions
Van der waals forces

Question 5

What is meant by a stable atom?

Answer 5

One in which the outermost orbital is completely occupied by electrons.

Question 6

What are the three classes of carbohydrates?

Answer 6

Monosaccharides, Disaccharides and Polysaccharides.

Question 7

Give examples of monosaccharides.

Answer 7

Glucose
Fructose
Galactose

Question 8

Give examples of disaccharides.

Answer 8

Sucrose
Lactose
Maltose

Question 9

Give examples of polysaccharides.

Answer 9

Starch (Storage)
Glycogen (Storage)
Cellulose (Structural)

Question 10

How are disaccharides formed?

Answer 10

By the bonding of two monosaccharides via a condensation reaction

Question 11

What is the first law of thermodynamics?

Answer 11

Energy is not created not destroyed, but rather converted from one form to another.

Question 12

What is the second law of thermodynamics?

Answer 12

When energy is converted from one form to another, some of that energy becomes unavailable for work. I.e no reaction is 100% efficient.

Question 13

What is an exergonic reaction?

Answer 13

Reactions where the total free energy of the products is less than the total free energy of the reactants.

Question 14

What is an endergonic reaction?

Answer 14

Reactions where the total free energy after the reaction is greater than the total free energy of the reactants.

Question 15

What are standard conditions for biochemists?

Answer 15

Temperature of 298 K
1 atmosphere of pressure
1M concentratoon of reactant (Except for H+)
pH=7

Question 16

Describe electronegativity. What is electronegativity dependant on?

Answer 16

When electrons are shared unequally between atoms in a molecule. This is dependant on the electronegativity of these atoms.

Question 17

What kind of substances dissolve in water?

Answer 17

Polar (Hydrophilic) substances

Question 18

What does D and L refer to when applied to amino acids?

Answer 18

The stereochemistry of the amino acid.

Question 19

How many “L” amino acids make up all proteins and polypeptides?

Answer 19

20

Question 20

What bonds are present in the folding of proteins?

Answer 20

Peptide bonds

Question 21

Which enzyme catalyses peptide bond formation?

Answer 21

Peptidyl transferase

Question 22

Describe acids in terms of donation or acceptance of Hydrogen ions.

Answer 22

Acids are Hydrogen ion donators.

Question 23

Describe bases in terms of donation or acceptance of Hydrogen ions.

Answer 23

Bases are Hydrogen ion acceptors.

Question 24

What determines the strength of an acid?

Answer 24

How readily it donates a proton to a base.

Question 25

What is pH?

Answer 25

The measurement of the amount of protons in a solution.

Question 26

What is a buffer solution?

Answer 26

A solution that controls the pH of a reaction mixture.

Question 27

What does the Henderson-Hasselbalch equation connect?

Answer 27

The Ka of a weak acid with the pH of a solution containing this acid.

Question 28

What is a zwitterion?

Answer 28

A molecule with a positive and a negative charge, hence no net charge.

Question 29

What is the isoelectric pH?

Answer 29

The pH at which a molecule has no net charge.

Question 30

What is meant by catabolism?

Answer 30

Breaking down complex molecules into smaller one releasing energy.

Question 31

Is a catabolic reaction endergonic or exergonic, and oxidation or reduction?

Answer 31

Endergonic and oxidation

Question 32

What is meant by anabolism?

Answer 32

Synthesising complex molecules out of smaller ones in energy consuming reaction.

Question 33

Is an anabolic reaction endergonic or exergonic, and oxidation or reduction?

Answer 33

Endergonic and reduction.

Question 34

What is meant by the term amphipathic?

Answer 34

Molecules that have hydrophobic and hydrophilic properties.

Question 35

Name and describe the 4 protein structures.

Answer 35

Primary- Sequence of amino acids.

Secondary- Localised conformation of the polypeptide backbone

Tertiary- 3D structure of an entire polypeptide, including all it’s side chains.

Quaternary- Spatial arrangement of polypeptide chains in a protein with multiple subunits

Question 36

Name the three distinct secondary protein structures.

Answer 36

Helix

Beta sheets 1

Beta sheets 2

Question 37

Name the two different types of tertiary protein.

Answer 37

Fibrous

Globular

Question 38

Name the forces which stabilise tertiary structures. (5)

Answer 38

Covalent disulphide bonds

Electrostatic interactions

Hydrogen bonds

Hydrophobic interactions

Complex formation with metal ions.

Question 39

What types of physical conditions disrupt protein structures? (4)

Answer 39

Heat

Extremes of pH

Detergents such as urea and guanidine hydrochloride

Thiol agents (Reducing agents

Question 40

Describe sickle cell anaemia.

Answer 40

A single nucleotide sequence change in coding region of the Beta chain of Haemoglobin A results in an altered protein (Valine instead of glutamic acid) causing SCA.