1.8 Proteins: Amino Acids Flashcards
The roles of proteins in living organisms The structure of amino acids The synthesis and breakdown of peptide bonds How to test for proteins
What are amino acids?
Monomers that can join together via a peptide bond to form dipeptides (dimers) and polypeptides (polymers)
How do amino acids join together?
Via peptide bonds
What are the roles of proteins?
(Name at least 4)
- Enzymes - proteins that are used to breakdown and synthesise molecules
- Antibodies - proteins that are involved in the immune response
- Transport - proteins that can move molecules or ions across membranes
- Structural components - proteins like keratin and collagen that are used to create strong fibres
- Hormones - proteins that can act as chemical measures in the body
- Muscle contraction - muscles are made up with proteins
What is the general structure of an amino acid?
- Central carbon
- an amino group (-NH2)
- a carboxyl group (-COOH)
- a hydrogen atom (-H)
- a R group or a variable side group
How many different amino acids are commonly found in living organisms?
Around 20
What determines the properties of an amino acid?
The R group
How are dipeptides synthesised?
By condensation reactions
How are dipeptides broken down?
By hydrolysis reactions
What type of bond joins amino acids?
Peptide bond
What happens in a condensation reaction of amino acids?
- The hydroxyl (OH) in the carboxyl group of one amino acid reacts with the hydrogen (H) in the amino group of the other amino acid
- Releases a water molecule (formed from the OH and the H from the hydroxyl and the amino group)
- Forms a peptide bond between the carbon of one amino acid and the nitrogen of another
What happens in a hydrolysis reaction of dipeptides?
The peptide bond is broken and water is added
How do you test for proteins?
Add Biuret solution
What is a positive result for proteins?
A purple solution
What is a negative result for proteins?
A blue solution
