Proteins Flashcards
Name Globular Proteins
• Enzymes, which are biological catalysts that control biochemical reactions such as
Amylase, which catalyses the digestion of starch.
• Transport proteins such as Haemoglobin, which transports oxygen.
• Signal proteins that carry messages around the body such as insulin a hormone
involving control of glucose levels in the blood.
• Contractile proteins such as actin and myosin, which are involved in muscle
contraction.
• Defensive proteins such as antibodies which defend the body against infection.
Name Structural proteins
Structural proteins
• Keratin which is found in nails and hooves.
• Collagen which is found in tendons.
What are Proteins made up of?
Proteins are made of monomers called amino acids.
How many different types of amino acids are there?
There are about 20 different types of
amino acids, all with the same general structure.
What is known as the general structure of an amino acid?
Each amino acid contains a central carbon atom to which a nitrogen containing amine group
(H2N or N2H) and a carboxyl group (COOH) are attached. The remaining group is referred to
as the ‘R’ group and differs in different amino acids.
What do two amino acids join together by a condensation reaction form?
Two amino acids join together to form a dipeptide by a condensation reaction.
What will a peptide chain always have at each end?
A peptide chain will always have an amine group at one end and a carboxyl group at the
other end.
Name the structures of a Protein?
There are four levels of organisation of proteins – these are known as the PRIMARY
structure, the SECONDARY structure, the TERTIARY structure, and the QUATERNARY
structure.
Describe the Primary structure of a protein.
The primary structure is the number
and sequence of amino acids in a
polypeptide chain.
Proteins differ from each other
because their primary structures
are different.
Polypeptides have many (usually hundreds) of the 20 naturally occurring amino acids
joined in any sequence, therefore there is a limitless number of possible combinations
and therefore primary protein structures.
• Primary structure determines its ultimate shape and hence its function.
A change in just a single amino acid can alter its shape and may prevent it carrying out its
function.
• A proteins shape is very specific to its function.
What does a primary structure determine of a Protein?
Primary structure determines its ultimate shape and hence its function.
Describe the secondary structure of a Protein
This is the way the polypeptide chain folds or coils into alpha helixes and beta pleated-
sheets. This structure is maintained by hydrogen bonds (weak bonds) between functional groups
What bonds form between the functional groups in the secondary structure of a Protein?
This structure is maintained by hydrogen bonds (weak bonds) between functional groups.
Describe what the tertiary structure of a protein means?
The R groups on the amino acids in the polypeptide
chain determine the how the polypeptide chain folds
into its specific three dimensional shape. This shape
is held together be bonds between R groups of
different amino acids.
How is the tertiary structure of a protein maintained?
This structure is maintained by 3 different types of
bonds between R groups:
• HYDROGEN BONDS, which are weak bonds.
• IONIC BONDS, also weak bonds, which form
between oppositely charged R groups.
• DISULPHIDE BRIDGES, covalent bonds, which
form between sulphur containing R groups (amino acid cysteine)
what does the tertiary structure of a protein determine?
The tertiary structure of the protein is essential to its function. The shape of the protein
determines how it reacts with other molecules e.g. active sites in enzymes.
