Proteins Flashcards
(24 cards)
What are amino acids?
building blocks of proteins which are essential macromolecules in organisms
AA’s are monomers that can join together via peptide bonds to form polypeptides
What are the role of proteins in living organisms?
Enzymes = used to breakdown and synthesise molecules
Antibodies = involved in immune response
Transport = can move molecules or ions across membranes
Structural components = e.g keratin and collagen used to create strong fibres
Hormones = act as chemical messengers in the body
Muscle contraction = muscles made up of proteins
What is the structure of an amino acid?
- central carbon atom
- amino group (-NH2)
- carboxyl group (-COOH)
- hydrogen atom (-H)
- R/variable group
What part of the amino acid determines it’s properties?
The R group
How are dipeptides formed via condensation reactions?
OH in carboxyl group of 1 amino acid reacts with the H in the amino group of another amino acid
releases a H2O and forms a peptide bond between the carbon of one amino acid and the nitrogen of another
How are dipeptides broken down via hydrolysis reactions?
H2O is added to a dipeptide breaking the bond to release 2 amino acids
What is the primary protein structure and what bonds are involved?
Unique amino acid sequence in the polypeptide chain
held together by peptide bonds
What is the secondary protein structure and what bonds are involved?
Polypeptide chain coil’s into either an alpha-helix or folds into a beta-pleated sheet structure
caused by H bonding between amino group and carboxyl group further down the chain
What is the tertiary protein structure?
Further folding/coiling of polypeptide chain to form complex 3D structure
What bonds are involved in the tertiary protein structure?
H bonds = individually weak but provide strength in numbers
Ionic bonds = between + and - R groups
Disulphide bridges = between sulphur containing R groups
Hydrophobic/hydrophilic = weak between polar/non-polar R groups
What is the quaternary protein structure?
2+ polypeptide chains held together by the same bonds found in the tertiary structure of a protein
can also involve addition of non-protein (prosthetic group)
What are globular proteins?
Compact, spherical and soluble proteins
What are some examples of globular proteins?
Enzymes = speed up chemical reactions in the body
Hormones = chemical messengers that travel in bloodstream
Antibodies =bind to and prevent pathogen spread
What are conjugated proteins?
Globular proteins also contain a non-protein element (prosthetic group)
What are the different types of prosthetic groups?
Lipids = combine with proteins forming lipoproteins
Carbohydrates = combine with proteins forming glycoproteins
Metal ions = e.g iron in haemoglobin
What are fibrous proteins?
Long strands that aren’t usually water soluble
What are some examples of fibrous proteins?
Keratin = found in the skin, hair, and nails
Collagen = found in connective tissues e.g bone and muscle.
Elastin = found in elastic connective tissue
What is the structure of haemoglobin?
4 polypeptide chains (quaternary structure) 2 alpha and 2 beta
each polypeptide chain contains a haem group (prosthetic group) which contains an iron atom making it a conjugated protein
What features of haemoglobin allow it to transport O2 around the body?
4 polypeptide chains = means 4 molecules of O2 can be carried
Haem group = contains iron that reversibly binds to oxygen
Compact structure = allows haemoglobin to fit inside RBC’s
Describe the structure of insulin?
Globular protein (hormone) and is used to regulate blood glucose concentration made up of 2 polypeptide chains held together by disulfide bonds
What is amylase and what is it’s structure?
Globular protein known as an enzyme, responsible for breakdown of starch into maltose
single polypeptide chain folded using both alpha-helixes and beta-pleated sheets
What is collagen and what is it’s structure?
Fibrous protein that’s a structural component in skin, tendons, cartilage, bones, teeth and blood vessel walls
3 polypeptide chains wound around each other in a rope-like structure, providing strength and flexibility
What is keratin and what is it’s structure?
Group of fibrous proteins found in the hair, skin and nails
large number of AA’s allowing disulfide bonds to form creating strong and insoluble molecules
can be flexible or rigid depending on number of disulfide bonds it contains
What is elastin and what is it’s structure?
Fibrous protein found in elastic connective tissue e.g blood vessel walls
elastic allowing tissues to expand and return to their original shape
