Biochemistry

Question 1

What is the first law of thermodynamics?

Answer 1

Energy is neither created nor destroyed, it can only be transferred from one form to another

Question 2

What is the second law of thermodynamics

Answer 2

When energy is converted from one form to another, some of that energy becomes unavailable to do work

Question 3

What are the building blocks of carbohydrates?

Answer 3

monosaccharides

Question 4

What is the difference between monosaccharides, disaccharides and polysaccharides?

Answer 4

mono- carbohydrates with single ring structure

di- double ring structure

poly- long chains of monosaccharides

Question 5

what are the 4 major classes of biomolecules

Answer 5

• peptides and proteins
• lipids
• nucleic acids
  -carbohydrates

Question 6

What are the meanings of entropy and enthalpy

Answer 6

entropy- disorder
enthalpy- heat content

Question 7

what is an exergonic reaction?

Answer 7

total free energy of products is less than total free energy of the reactants- reactions can occur spontaneously.

Question 8

What is an endergonic reaction?

Answer 8

total free energy of the products is more than the total free energy of the reactants - cannot occur spontaneously

Question 9

What do endergonic reactions require in order to proceed?

Answer 9

An input of energy

Question 10

How is the free energy related to equilibrium?

Answer 10

Reversibility of the reaction increases the closer the free energy is to zero.

Question 11

In what way can endergonic reactions be allowed to proceed

Answer 11

When this unfavourable reaction is coupled to a favourable exergonic reaction

Question 12

What does metabolism mean?

Answer 12

All of the chemical reactions taking place within the body

Question 13

What is meant by catabolism?

Answer 13

Breaking down complex molecules into smaller ones and releasing energy

Question 14

Are catabolic reactions exergonic or endergonic

Answer 14

exergonic reactions- energy yielding

Question 15

what is meant by anabolism

Answer 15

Synthesising complex molecules out of smaller ones in energy consuming reactions

Question 16

Are anabolic reactions exergonic or endergonic

Answer 16

endergonic reactions - require energy

Question 17

What is a polar molecule?

Answer 17

A molecule in which electrons are shared unequally due to a difference in electronegativity, this causes a difference in charge from one side of the molecule to the other.

Question 18

What shape do water molecules have and how are they held together?

Answer 18

They have a tetrahedral shape and they are held together with hydrogen bonds

Question 19

What is a hydrogen bond?

Answer 19

A covalent bond between hydrogen and a more electronegative atom that creates a polarised bond

Question 20

Are hydrogen bonds reversible or irreversible?

Answer 20

They are reversible and allow reversible change in biomolecules

Question 21

What is an amphipathic molecule?

Answer 21

Molecules which are both hydrophilic and hydrophobic, they have a polar head at one end and a non polar tail at the other end

Question 22

What is the common structure of all amino acids?

Answer 22

an alpha carbon bonded to
- an amine group
- a carboxyl group
- a hydrogen
- an R group

Question 23

what are the 4 classifications of amino acids?

Answer 23

• hydrophobic
• polar
• acidic
• basic

Question 24

What is a peptide bond?

Answer 24

The bond that links amino acids.

Question 25

What are peptide bonds important for?

Answer 25

They are important for the folding of proteins

Question 26

What are the two ends of a peptide called

Answer 26

The start is called the N - terminal residue and the end is called the C- terminal residue

Question 27

Is a base a proton donor or acceptor?

Answer 27

Proton acceptor

Question 28

Is an acid a proton acceptor or donor?

Answer 28

Proton donor

Question 29

What does the strength of an acid depend on?

Answer 29

How readily it donates a proton to a base

Question 30

What is the PH a measure of?

Answer 30

Measurement of the amount of protons in a solution

Question 31

How do you calculate the PH of a substance?

Answer 31

PH= -log10[H+]

Question 32

What is the purpose of the Henderson Hasselbach equation?

Answer 32

connects the Ka of a weak acid with the PH of a solution containing this acid

Question 33

What is the Henderson- Hasselbalch equation?

Answer 33

pH=pKa+ log[A]/[HA]

Question 34

What is the purpose of a buffer solution?

Answer 34

To control the PH of a reaction mixture -

Question 35

How does changing PH affect a protein?

Answer 35

It can change the ionisation of the protein therefore changing its structure and function

Question 36

What is the primary structure of a protein?

Answer 36

The sequence of the amino acids in the polypeptide

Question 37

What is the secondary structure of a protein?

Answer 37

Localised conformation of the polypeptide backbone

Question 38

What are the three types of secondary structure?

Answer 38

Alpha helix, beta pleated sheets and triple helix

Question 39

What type of bonding is involved in the secondary structure of proteins?

Answer 39

Hydrogen Bonding

Question 40

What is the tertiary structure?

Answer 40

The 3D structure of an entire polypeptide

Question 41

What are the two types of tertiary structures?

Answer 41

Fibrous proteins - e.g collagen (insoluble in water)

Globular proteins- spherical (haeoglobin) - soluble in water

Question 42

What is the quaternary structure?

Answer 42

The spatial arrangement of polypeptide chains in a protein with multiple subunits

Question 43

example of a protein with a quaternary structure?

Answer 43

Haemoglobin