2.9 Proteins and amino acids

Draw and explain the structure of an amino acid

amino acids are the monomers of polypeptides

• they consist of an amine group -NH₂

• a carboxylic acid group -COOH

• a hydrogen atom

• an R group —→ which is different how each amino acid differs

Draw the reaction for how a peptide bond is formed

Explain how a peptide bond is formed, include

• how a dipeptide bond is formed

• how a polypeptide bond is formed

a peptide bond is formed from a condensation reaction

• this is between the carboxylic acid of one amino acid and the amino group of another, between the carbon (which has a double o bond) and the nitrogen

a dipeptide is two amino acids joined together releasing water

a polypeptide bond is more than two or many amino acids

Describe the primary structure of proteins

• include the type of bonds present

• drawing of how the structure looks like

this is the sequence of amino acids held together by peptide bonds only

• it is a singular polypeptide chain

Describe the secondary structure of proteins

• include the type of bonds present

• drawing of how the structure looks like

this is the sequence of amino acids that coil and fold due to the interactions between amino group and carboxyl group of 2 amino acids

Describe the tertiary structure of proteins

• include the type of bonds present

• drawing of how the structure looks like

this is the combination of different secondary structures within the same polypeptide chain

held together by

• hydrogen bonds (strong collectively, between R groups)

• ionic bonds (between charged R groups)

• disulphide bonds (only occurs between cysteine amino acids)

• hydrophobic & hydrophilic interactions (between polar & non-polar groups)

Describe the tertiary structure of proteins

• include the type of bonds present

• drawing of how the structure looks like