2.2 Proteins Flashcards
What are globular proteins?
Proteins formed by compact amino acid chains, then folded into intricate chains that resemble spheres
Are globular proteins soluble or insoluble in water?
Soluble
Give an example of a globular protein and what it does:
Insulin, which is produced by the pancreas, it aids the bodies ability to regulate energy and metabolize sugars
What does insulin illustrate?
A proteins ability to act as a biological messenger
What else can proteins act as?
Biological transport mechanisms and they can play a role in the structure of animal cells
What are conjugated proteins?
(Non-polypeptide) Proteins that function in interaction with other chemical groups
What are conjugated proteins attached by?
They are attached by covalent bonds (weak interactions)
Are conjugated proteins soluble or insoluble in water?
Soluble in water
What are proteins?
Long chains of amino acids, they are a diverse group of large and complex molecules
Give an example of conjugated proteins:
- haemoglobin
* catalase
What are fibrous proteins?
A proteins with a elongated shape forming a rod or wire like shape
What do fibrous proteins provide?
Structural support for cells and tissues
Give examples of fibrous proteins:
- keratin
- elastin
- collagen
Are fibrous proteins soluble or insoluble in water?
Insoluble
What breaks down proteins?
Protease enzymes
What is a prosthetic group?
A non protein component in globular proteins
What are proteins without a prosthetic group called?
Simple proteins
What is formed when a lipid and protein combine?
A lypoprotein
What is a glycoprotein?
When a carbohydrate combines with a protein
What is a COFACTOR?
A prosthetic group formed by metal ions and vitamins
Give an example of a prosthetic group?
HAEM group - contain an iron ion
What contains HAEM groups?
Catalase and haemoglobin
What do protease enzymes break down?
Peptide bonds
How does the protease enzyme denature the protein?
It breaks the bonds, altering the structure, it first breaks the hydrogen, then the ionic then the disulphide
What changes in the structure of amino acids?
The R group changes, but all amino acids have the same general structure
What are the four structures of proteins?
- primary structure
- secondary structure
- tertiary structure
- quaternary structure
How many naturally occurring amino acids are there?
There are 20 naturally occurring amino acids each with their own R group
How is a polypeptide chain formed?
When amino acids are added to a dipeptide
How many polypeptides does one protein consist of?
One polypeptide
What is polymerisation? And what type of reaction is this?
The process in which amino acid monomers are joined to form a polypeptide, this is a condensation reaction
What are the types of proteins?
- structural
- catalytic
- signalling
- immunological
What are structural proteins?
They are the main component of body tissues such as muscle, skin, hair and ligaments
What are catalytic enzymes?
All enzymes are proteins catalysing many biochemical reactions
What are signalling proteins?
Hormones and receptors (many of these are proteins)
What are immunological proteins?
Antibodies are proteins
Where is a disulphide bridge formed?
Between two cystine amino acids
What does the primary protein structure look like? And what bond joined them?
A long chain of amino acids joined by polypeptide bonds
What doe the primary structure of a protein determine?
It’s shape and function
What are the two secondary structures?
- alpha helix
* beta pleated sheet
What bond does the secondary structure contain?
Weak hydrogen bonds
How are the weak hydrogen bonds form?
The positive charge on the hydrogen and the negative charge of the oxygen
What do the hydrogen bonds cause in the secondary structure?
Causes the long polypeptide chains to twist into a 3D helix
What is the tertiary structure?
The 3rd protein structure it is a further folded and twisted to give it a more complex 3D structure
How is the tertiary structure maintained?
By a number of bonds
What bonds are contained in the tertiary structure?
- disulphide bonds
- ionic bonds
- hydrogen bonds
What are disulphide bonds?
Bridges formed between cystine they are strong and difficult to break
What are ionic bonds?
Bonds formed between carboxyl and amino groups that are not involved in the formation of peptide bonds, they are weaker than disulphide bridges
What are hydrogen bonds like?
They are numerous however they are weak and easily broken
What is the bond between two amino acids?
A peptide bond
How are peptide bonds formed?
The joining of amino acids by a condensation reaction
