Lecture 4

Question 1

Outline some important functions of proteins

Answer 1

Storage of amino acids (proteins)
Structural support
Transport of substances
Protection against disease (defensive)

Question 2

Distinguish between an amino acid, a polypeptide and a protein

Answer 2

Amino acids are made up of three specific nucleotides
A polypeptide chain is a sequence of amino acids.
A protein is a polypeptide chain folded in a specific conformation.

Question 3

Explain the structure/function and how it relates to macromolecules of proteins

Answer 3

A polymers function is determined how the monomer
for example proteins, The shape of a protein is determined by its primary structure (sequence of amino acids). The sequence of amino acids in a protein is determined by the sequence of nucleotides in the gene (DNA) encoding it.

Question 4

Describe and explain the important roles of weak interactions in biological molecules and distinguish weak interactions from covalent bonds (polar and non-polar)

Answer 4

Weak interactions determine how the proteins fold.
A covalent bond is a permit linkage whereas weak interactions is temporary, it can be broken and other interactions/linkages can occur in further folding of the protein structure. Secondary - Tertiary folding.

Question 5

Important properties of weak interactions

Answer 5

Have a cumulative effect - individually they are weak
They are reversible
They are transient

Question 6

Recognise, define and describe the four levels of protein structure

Answer 6

Primary level - a specific sequence of amino acids, if a single amino acid is changed this can result in a dramatic effect.
Secondary level - a of polypeptide is any regular coiling/folding. Produced by hydrogen bonds between NH and CO groups of the polypeptide backbone. There are two types of a-helix and b-pleated sheets
Tertiary level - irregular folding pattern produced by weak interactions between R groups of the polypeptide. Has hydrophobic interactions as the polypeptide tends to found so non-polar R groups are buried inside
Quaternary structure - held together by weak interactions but also linked by covalent bonds. Have (3 collagen subunits) and (4 hemoglobin subunits)

Question 7

What is the building block principle

Answer 7

New amino acids are always added to the C-terminal end when proteins are made in the cell

Question 8

What are the levels of weak interactions

Answer 8

Ionic interactions - Interactions between ions in a solution
Hydrogen bonds - help with shape and solubility
Hydrophobic effect - important for final conformation
Van der Waals interactions - Stabilize structure

Question 9

Explain what denaturation is and describe its effect on protein function

Answer 9

The unfolding of a protein, due environmental changes - causing loss of biological function

Question 10

Define the terms enzyme and substrate and discuss how enzymes work

Answer 10

Enzyme - a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction
Substrate - the substance on which an enzyme acts
Enzyme increase the rate of reactions in the form of a catalyst