week 2: Macromolecules - Protein (S&F)

Question 1

7 functions of proteins

Answer 1

1. enzymes –> catalises reactions
**2. transport –> ** binds and carries ions or molecules to other sites. (e.g. haemoglobin carries oxygen)
**3. structural –> ** strenght and protection (e.g. elastin, karatin, collagen,
4. receptors –> glycoproteins on the extracellular surface of the cell membrane.
5. defence –> antibodies
**6. regulation –> ** cellular and physiological activity - hormones (e.g. insulin in glucose reulation)
7. contractile –> enables cells or organisms to contract/move. (e.g. myosin, actin, flagellin)

Question 2

how are amino acids classified?

Answer 2

• essential amino acids = must be obtained through diet as body cannot synthesise them.
• non-essential amino acids = can be produced in the body.

Question 3

what is the general structure of amino acids?

Answer 3

amine group (NH2) on end and a carboxyl group (COOH) on the other end attached to a alpha carbon atom in the middle.
hydrogen atom also attached to the alpha carbon at the top and a R group (variable group) attached to the bottom of the carbon

Question 4

what determines the type of amino acid?

Answer 4

• the R group (variable group) attached to the alpha carbon determines the type of amino acid.

Question 5

what is a PTM (post tranlational modification)?

Answer 5

• there are 20 standard amino acids that naturally exist; non-standard amino acids are found in specialised proteins
• PTM creates non-standard amino acids where chemical modification occurs after translation of mRNA into a polypeptide chain.
• this includes addition of hydroxyle group or a phosphate group through covalent bonds. –> this changes the properties of the proteins and hence, the function.

Question 6

why are proteins important to oral health professionals?

Answer 6

• many oral health diseases (e.g. scurvy) relate to modified amino acids (e.g. hydroxyproline and hydroxylysine).
• scurvy can impact gingia and teeth –> leading to gingival bleeding, loosned teeth (loss of periontal ligaments), and tooth decay.

Question 7

difference between peptide and protein

Answer 7

**- **a peptide is a short chain of two or more amino acids
- a protein is a long molecule made up of multiple peptide subunits - AKA polypeptides.
- both are made up of amino acids joined together by aminde (peptide) linkages - covalent bonds.

Question 8

what peptide is commonly used as a sweetening agent?

Answer 8

aspartame - intense sweetner added to low-energy or sugar-free foods
(e.g. in coke zero)

Question 9

Name the 4 levels of proteins architecture?

Answer 9

1. primary
2. secondary
3. tertiary
4. quaternary

Question 10

what is a primary protein?

Answer 10

• sequence of amino acids –> in a polypeptide chain.
• have a specific number and sequence of amino acids which determine its structure.

Question 11

what is a secondary protein structure?

Answer 11

• 2D folding of the polypeptiode chain
• forms alpha-helix or beta-pleated sheets
• adjacent amino acids interact, hence, forming hydrogen bonds between eachother –> forming the 2D shape
• this determins the function of protein

Question 12

what is the tertiary protein structure

Answer 12

• a 3D folding of the polypeptide chain

Question 13

what is the quaternary structure of proteins?

Answer 13

• joining of 2 or more polypeptide chains to create a 3D protein.

Question 14

what are the 3 common types of weak non-covalent bonds that stabalise proteins?

Answer 14

1. hydrogen bonds
2. hydrophobic interactions
3. van der waals

Question 15

what can disrupt the weak non-covalent bonds of proteins and what is the effect?

Answer 15

• when excess heat is applied to –> denature the non-covalent bonds between amino acids –> change in structure –> effecting function.
• changes in pH can lead to losing a proton –> also denaturing the non-covalent bonds –> impact the structure and function of the protiens.