2.2-Proteins 1: Amino acids

Question 1

What does amino acids mean?

Answer 1

Monomeers of all proteins and all amino acids have the same basic structure

Question 2

What is a peptide bond?

Answer 2

A bond formed when two amino acids are joined by a condensation reaction

Question 3

What are proteins?

Answer 3

Proteins are large polymers comprised of long chains a of amino acid. The properties of protein give them a variety of functions:

• They form structural components of animals in particular. For example, muscles are made of protein.
• Their tendency to adopt specific shapes makes proteins important as enzymes, antibodies and some hormones.
• Membranes have protein constituents that act as carriers and pores for active transport across the membrane and facilitated diffusion.

Both plants and animals need amino acids to make proteins. Animals can make some amino acids, but must ingest the other (called essential amino acids). Plants can make all the amino acids they need but only if they can access fixed nitrogen.

Question 4

WHat is the strcutre of amino acids?

Answer 4

Each aminoacids contais the elemets C, H, O and N. SOme animo acids contain sulphur.
- There are over 500 different amino acids but only 20 of them are proteingenic, whci means they are found in proteins. Each protein cain of amino acids has an amin group (-NH2) at one end and a carboxyl (-COOH) group at the other end.
The R in the drawn equationdeos stand for an element but is different in each amino acid. In glycine it is simpoly an H atom.
However, in other amino acids, the R group can be more complicated. For example in alanine it is CH3, whreasin cysteine it is CH3S. The name of alkmost all amino acids ends in- ine. The only exception are those which have an acidic R group, such as aspartic acid and glutamic acid. R groups can vary in size, by charge and by polarity, with some being hydrophobic and some being hydrophilic

Question 5

Explain the peptide bond:

Answer 5

Amino acuds are joined tofehtr by covalent bonds called peptide bonds. Just likeglycosidc and ester bonds, making a pepetide bond involves condensation reaction and breaking a peptide bond involes hydrolysis. Enzymes catalyse these reaction. Protease enzymes in the intestine break pepetide bonds during digestion. They also break downprotein hromoes so that their effect are not permanent.
-All amino acids join togehtr in the same way whatever R group tey may have. Two amino acis joined together are known as dipeptide. Joining a large chani of amino acids together formd a polypepetide. A protein may consist of a single polpeptide chain or more than one chain bonded together.