Biomolecules 2 Flashcards
what are peptide bonds
Proteins are heteropolymers of amino acids. Proteins are polypeptides. They are linear chains of
amino acids linked by peptide bonds
how are peptide bonds formed?
Peptide bond is formed when the carboxyl group of one amino acid is linked with the amino group of second amino acids leading to the loss of 1 h2o molecule called Decondensation reaction.
Addition of 1 water molecule leads to the breaking of bond called hydrolysis.
why is protein is called heteropolymer
Each protein is a polymer of amino acids. As there
are 20 types of amino acids (e.g., alanine, cysteine,
proline, tryptophan, lysine, etc.), a protein is a
heteropolymer and not a homopolymer. A
homopolymer has only one type of monomer repeating
‘n’ number of times. A polymer composed of different subunits is a heteropolymer
what is the most abundant protein
Collagen is the most abundant protein in animal world
and Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO) is the
most abundant protein in the whole of the biosphere.
name some proteins and their functions
collagen- intercellular round substance
melanin- pigments
trypsin- enzyme
insulin- hormone for metabolism of glucose
glut-4 enables glucose transport into cell
antobodies ( immunoglobulins)- fights infectious agents
receptors- chemical signalling/ sensory reception/ neural impulse
histones- packing of dna
what is the primary structure of proetin
it is a single polypeptide chain like a thread. It has the free amino group of one end called the N-terminal and a free carboxyl group on the other end called C-terminal. It does not exist as a rigid rod throughout
what are the secondary structures of proteins
There are two types
-alhpa helix
a single polypeptide chain which is become helical or coiled due to hydrogen bonding between 1st and 4th amino acids. In proteins only right hand helices are observed
-beta pleated sheet
consits of 2 parallel polypeptide chains which are connected by hydrogen bonds. this given a stepped sheet like appearance
what is the teritary
it is thr 3-d structure formed by various interactiosn between amino acids in the form of ionic bonds, pepetide bonds, hydrogenbonds, disulphisde bonds and hydrophobic interactions, .
this foleded appearances gives rise to a crevice which creates a befitting space for substrate molecule for enzymatic catalysis
what is qauternary protein
Some proteins are an assembly of more than one polypeptide or
subunits. The manner in which these individual folded polypeptides
or subunits are arranged with respect to each other (e.g. linear string
of spheres, spheres arranged one upon each other in the form of a
cube or plate etc.) is the architecture of a protein otherwise called
the quaternary structure of a protein
Haemoglobin present in rbc is a quaternary protein which consits of 4 tertiary subunits. two subunits are identical. There are two alpha and two beta chains connected by iron atoms.
what are lipids
lipids are water insoluble.
they are made up of fatty acids and glycerol.
what are lipids made up of
A fatty acid has a carboxyl group attached to an R group. The R group
could be a methyl (–CH3
), or ethyl (–C2H5
) or higher number of –CH2
groups (1 carbon to 19 carbons).
For example, palmitic acid has 16
carbons including carboxyl carbon. Arachidonic acid has 20 carbon
atoms including the carboxyl carbon. Fatty acids could be saturated
(without double bond) or unsaturated (with one or more C=C double
bonds). Another simple lipid is glycerol which is trihydroxy propane.
what are glycerides
when a fatty acid is esterified with a glyclerol then its a glyceride. They can be monoglyceride, di glyceride or triglyceride depending upon how many fatty acids react with the glycerol. (the max is 3 coz only 2 oh grps)
differentiate between fats and oils
oils
-unsaturated
-has double bonds
- healthier
-lower melting point and hence liquid
- usually plant origin
fats
-saturated
-single bonds
-not very healthy
-high melting point so it is soft waxy solid
- usually animal origin
what are phospholipids
Some lipids
have phosphorous and a phosphorylated organic compound in them.
These are phospholipids. They are found in cell membrane. Lecithin is
one example. Some tissues especially the neural tissues have lipids with
more complex structures.
