Biomolecules 3 Flashcards
define enzymes
Enzymes are biocatalysts, which allow the various metabolic reactions in our body to occur in mild conditions.
Almost all the enzymes are globular
proteins.
Enzymes are very specific for a particular reaction and for a
particular substrate.
They are generally named after the compound or class of compounds upon which they work.
For example, the enzyme
that catalyses hydrolysis of maltose into glucose is named as maltase.
C12H22O11 –Maltase–>2 C6H12O6
naming of enzyme
Sometimes enzymes are also named after the reaction, where they are used. For example, the enzymes which catalyse the oxidation of one substrate with simultaneous reduction of another substrate are named as oxidoreductase enzymes. The ending of the name of an
enzyme is -ase.
Mechanism
of Enzyme
Action
Enzymes are needed only in small quantities for the progress of a reaction.
Similar to the action of chemical catalysts, enzymes are said to reduce the magnitude of activation energy.
define vitamins
They are generally regarded as organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism.
where are vitamins found
Most of the vitamins cannot be
synthesised in our body but plants can synthesise almost all of them,
so they are considered as essential food factors. However, the bacteria
of the gut can produce some of the vitamins required by us. All the
vitamins are generally available in our diet.
classification of vtiamines
Vitamins are classified into two groups depending upon their solubility
in water or fat.
(i) Fat soluble vitamins: Vitamins which are soluble in fat and oils
but insoluble in water are kept in this group. These are vitamins A,
D, E and K. They are stored in liver and adipose (fat storing) tissues.
(ii) Water soluble vitamins: B group vitamins and vitamin C are soluble
in water so they are grouped together. Water soluble vitamins must be supplied regularly in diet because they are readily excreted in urine and cannot be stored (except vitamin B12) in our body.
nucleic acids
The particles in nucleus of the cell, responsible for
heredity, are called chromosomes which are made up of proteins and
another type of biomolecules called nucleic acids. These are mainly
of two types, the deoxyribonucleic acid (DNA) and ribonucleic acid
(RNA). Since nucleic acids are long chain polymers of nucleotides, so
they are also called polynucleotides.
hydrolysis of nucleic acids yields
Complete hydrolysis of DNA (or RNA) yields a pentose sugar, phosphoric
acid and nitrogen containing heterocyclic compounds (called bases). In
DNA molecules, the sugar moiety is b-D-2-deoxyribose whereas in
RNA molecule, it is b-D-ribose.
DNA contains four bases viz. adenine (A), guanine (G), cytosine (C) and thymine (T). RNA also contains four bases, the first three bases are
same as in DNA but the fourth one is uracil (U).
differentiate between nucleotide and nucleoside
A unit formed by the attachment of a base to 1’ position of sugar is
known as nucleoside. In nucleosides, the sugar carbons are numbered
as 1¢, 2¢, 3¢, etc. in order to distinguish these from the bases
(Fig. 10.5a). When nucleoside is linked to phosphoric acid at 5¢-position
of sugar moiety, we get a nucleotide
primary and secondary structure of dna
Information regarding the sequence of nucleotides in the chain of a nucleic acid is called its primary structure.
Nucleic acids
have a secondary structure also. James Watson and Francis Crick
gave a double strand helix structure for DNA (Fig. 10.7).
Two
nucleic acid chains are wound about each other and held together
by hydrogen bonds between pairs of bases.
The two strands are
complementary to each other because the hydrogen bonds are
formed between specific pairs of bases. Adenine forms hydrogen
bonds with thymine whereas cytosine forms hydrogen bonds
with guanine.
rna
In secondary structure of RNA single stranded helics is present
which sometimes foldsback on itself. RNA molecules are of three
types and they perform different functions. They are named as
messenger RNA (m-RNA), ribosomal RNA (r-RNA) and transfer
RNA (t-RNA).
DNA is the chemical basis of heredity and may be regarded as the reserve
of genetic information. DNA is exclusively responsible for maintaining
the identity of different species of organisms over millions of years. A
DNA molecule is capable of self duplication during cell division and
identical DNA strands are transferred to daughter cells. Another important
function of nucleic acids is the protein synthesis in the cell. Actually, the
proteins are synthesised by various RNA molecules in the cell but the
message for the synthesis of a particular protein is present in DNA.
