Q: Describe the structure of an amino acid and the formation of a peptide bond.

Proteins are made up of organic molecules called amino acids. There are thousands of different proteins with diverse functions: storage, transport, structural support, cellular communication, enzymes and hormones.

However, all these proteins are constructed from the same set of 20 amino acids, linked together in polymers.

The amino acids in a protein are bonded to each other with peptide bonds - hence the term for a polymer of amino acids is a polypeptide.

There are 20 different amino acids, and they all share the same general structure. In the centre of the amino acid is an assymetric carbon atom called the alpha carbon. This carbon is covalently bonded to four different groups: an amino group, a carboxyl group, a hydrogen atom, and a variable group symbolised by R. 

The R group (also known as a side chain) is different for each of the 20 amino acids. For example the amino acid Alanine has a methyl group at this position, whereas Glycine has a hydrogen atom.

The amino group of one amino acid will bond to the carboxyl group of the next amino acid. This bond is called a peptide bond and it is formed by a dehydration reaction, where a water molecule is removed

Many amino acids joined by peptide bonds form a polypeptide.

Answered by Florence M. Biology tutor

21787 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Discuss the basis and variable outcomes of gene mutations


How does does changing the pH affect the activity of an enzyme?


Measles, mumps and rubella (MMR) are dangerous diseases that can be fatal to children. The MMR vaccine is given to children at a young age to produce antibodies against these diseases. Describe how giving the vaccine leads to the production of antibodies.


What is the role of a myelin sheath in neurones?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences