Proteins Flashcards
What are the 7 classes of amino acids?
Aliphatic, aromatic, acidic, basic, sulfur-containing, polar and miscellaneous
What is a protein?
A macromolecule consisting of amino acids
How does DNA link to protein?
DNA tells cells how to make mRNA, which acts as a blue print for amino acid chain formation
How many naturally occurring amino acids are there?
20
How many nucleotides code for an amino acid?
3
What are the nucleotides in DNA and mRNA?
ATCG and AUCG
What is the structure of an amino acid?
Central carbon attached to an amine (NH2), carboxyllic acid (-COOH), hydrogen and R-group
Do amino acids have any charge at a pH of 7?
They are zwitterions so there is a (NH3)+ and -(COO-) at a pH of 7
What are the two types of proteins in use and an example of each?
Structural - keratin and Functional - antibodies/enzymes
What is the primary protein structure?
Chain of amino acids bound by peptide bonds - polypeptide chain
What is the secondary protein structure? What are the 2 types?
3D spacial structure relying on hydrogen bonding between partially negative -O and -H. Can be Alpha helix or Beta plaited sheet
What is the tertiary protein structure?
Still 1 polypeptide chain but -R groups interact with ionic bonding, hydrogen bonding, disulphides bridges and hydrophilic and hydrophobic interactions.
What is the quaternary protein structure?
Involves +1 polypeptide chain, e.g. haemoglobin (4)
What is denaturation?
When a protein can no longer fulfil its function due to disruption or destroyed bonds. The amino acid retains its identity, but cannot function.
What features do protein channels have that assist their function?
The proteins amino acids can be hydrophilic or hydrophobic, assisting specific molecules, e.g. water, in passing through
What are three forms of conjugated protein?
Glycoproteins, lipoproteins, metalloproteins
What is a conjugated protein?
A protein which undergoes an additional post-transitional change and gains a non-protein group.
What is a glycoprotein?
A protein with 1+ carbs attached. If a few are in a chain its an oligosaccharide.
What qualities do glycoproteins have?
Increased stability, altered solubility, folds/bends in chain, cell-cell communication
What is a lipoprotein and its benefits?
Proteins combines with lipids. Transport hydrophobic molecules around the blood, like cholesterol
What are metalloproteins and an example?
Proteins with a metal ion in its structure. E.g. Iron ion (Fe+) in haem
What are the 3 classifications of protein structure?
Globular, Fibrous and Membranous proteins
What is an example of a globular protein?
Immunoglobulin and enzymes
How does solubility vary between globular and fibrous proteins?
Globular - high solubility in water. Fibrous - low solubility in water
What are some examples of fibrous proteins?
Keratin, collagen, fibril, elastin
What are the uses of fibrous proteins?
Have a rope like structure so form connective tissue, muscle fibres and tendons. High tensile strength
What are membranous proteins with examples?
Proteins embedded in cell membrane. Aquaporins in cell membrane or glycoproteins
What is a G protein?
Peripheral proteins found on the inner membrane, responsible for translocate messages for receptor proteins to other proteins on the membrane - e.g. enzymes or ion channels
