amino acids Flashcards
Draw the general structure of an amino acid (4)
A central carbon with a hydrogen;
An amine group, a carboxyl group and an R group (variable group -
the R group is the difference between different amino acids)
What are amino acids in relation to proteins? (1)
Monomers of proteins / polypeptides
What is a dipeptide? (1)
Formed when two amino acids are joined together by a peptide bond
What is a polypeptide? (1)
Formed when two or more amino acids are joined together by a peptide bond
What are proteins made of? (1)
One or more polypeptides
How are amino acids joined together in proteins? (2)
By peptide bonds.;
These bonds are formed by condensation reactions between the amino group of one amino acid and the carboxyl group of another
How can peptide bonds be broken? (2)
By a hydrolysis reaction;
Which adds a molecule of water to break the bond
What is the primary structure of a protein? (2)
The sequence of amino acids in the polypeptide chain;
That are held together by peptide bonds
What is the secondary structure of a protein? (2)
The coiling or folding of a polypeptide chain;
By hydrogen or ionic bonds
What are the two examples of secondary structures of a protein? (2)
α-helix
β-pleated sheet
What is the tertiary structure of a protein? (2)
The further folding and coiling of the secondary structure to form the final 3D shape;
Due to hydrogen, ionic and sometimes disulphide bonds
What is the quaternary structure of a protein? (2)
Proteins made up of more than one polypeptide chain;
E.g. haemoglobin
What are globular proteins? (1)
Spherical and compact proteins
What are the properties of globular proteins? (2)
Soluble
Easily transported in fluids
What is haemoglobin, and what is its function? (3)
A globular protein that carries oxygen around the body in red blood cells;
Contains 4 haem groups;
Consists of four polypeptide chains, each with a haem group
What is insulin, and what is its function? (2)
Hormone that is secreted by the pancreas that helps regulate blood glucose levels;
Consists of two polypeptide chains held together by disulphide bonds
What is amylase, and what is its function? (3)
Amylase is an enzyme that catalyses the breakdown of starch;
It consists of a single polypeptide chain;
Its secondary structure contains both α-helices and β-pleated sheets
What are the key properties of fibrous proteins? (4)
Insoluble;
Strong;
Structural;
Fairly unreactive
What are three examples of fibrous proteins? (3)
Collagen
Keratin
Elastin
What is collagen, and what is its function? (2)
Collagen is a fibrous protein found in animal connective tissues (bone, skin, muscle);
It is very strong, and minerals like calcium can bind to it to increase its rigidity
What is elastin, and what is its function? (2)
Elastin is a fibrous protein found in elastic connective tissues;
It is elastic, allowing tissues to return to their original shape after being stretched
