proteins Flashcards
What percentage of the human body is protein?
18%
Name some examples of the functions of proteins.
Enzymes, structural proteins, signalling proteins, storage proteins, antibodies in the blood, transport proteins.
What features do all amino acid’s have?
They all have an Amine group at one end, and a carboxyl group at the other.
What is the variable part of an amino acid?
The R group
How many types of amino acid occur in life?
20 occur in life – this refers to the amount of R groups
What is the simplest R group?
Glycine which is simply one hydrogen
What amino acid R group does every protein start with?
Methionine, shown by the simple capital M
What properties can R groups have?
They can be: nonpolar, hydrophobic, polar, hydrophilic, ionic etc
What is the name for two amino acids joined together?
To amino acid is joined together by peptide bond are called a dipeptide.
What is a protein?
A molecule consisting of one or more polypeptide chain.
Where is a peptide bond formed?
A peptide bond is formed between the Amine group of one amino acid and the carboxyl end of the other.
What is a simple protein?
A simple protein is a protein containing amino acids only.
What is a conjugated protein?
Containing a non-amino acid part which is called a prosthetic group.
What is meant by the term primary structure?
The order of amino acid’s within a protein
What is meant by secondary structure? And what are the two types?
Secondary structure is when the polypeptide chain begins to fold it can do this in two ways: the first is an alpha helix, the second is called a beta pleated sheet.
What bonds are involved in the secondary structure?
Hydrogen bonds form between nonadjacent amino acids - this holds the secondary structure in place.
What is meant by the tertiary structure?
The overall three-dimensional shape of a polypeptide chain after it has coiled in multiple ways.
Name the types of bonds that hold the tertiary structure in place.
Bond between R groups include: Ionic bonds, hydrogen bonds, disulphide bonds, and hydrophobic interactions.
Describe the term fibrous protein.
Fibrous proteins consist of parallel polypeptide chain is cross-linked at intervals to form long fibres or sheets. Fibrous proteins are usually in soluble in water and physically tough which suits them for them mainly structural functions.
Describe what is meant by the term globular protein.
Are globular protein is when the polypeptide chain is tightly folded to form a spherical shape. Many globular proteins are folded so that the hydrophobic groups on the inside of the molecule and the hydrophilic groups face outwards, making these proteins soluble in water.
What is meant by the term quaternary structure?
When a protein is made up of more than one polypeptide chain.
Give some information about the structure and function of insulin.
It is a globular protein.
It is a hormone that regulates blood glucose concentration.
It is soluble as it is transported in blood and as a precise shape to fit specific receptors.
It only has a tertiary structure.
Give some information about the structure and function of haemoglobin.
It has a good quaternary structure made of four polypeptides.
This consists of two alpha and to beta subunits.
Each sub unit contains a prosthetic haem group. This is able to combine reversibly with oxygen.
It is soluble and globular as in blood it is used for transport.
Give some information about the structure and function of catalase.
Catalase is an enzyme, which increases reaction rates in specific reactions.
It has a Quaternary structure and also contains four haem groups.
Iron 2 ions in these haem groups allow it to interact with hydrogen peroxide and speed up its decomposition.
