Chemistry 2 Marks Questions

→"Hormones are molecules that act as intracellular messengers. These are produced by endocrine glands in the body and are poured directly in the blood stream which transports them to the site of action."
→" In terms of chemical nature, some of these are steroids. e.g. estrogens and androgens, some are polypeptides for example insulin and endorphins and some others are amino acid derivatives such as epinephrine and norepinephrine.

→DNA is the chemical basis of heredity and may be regarded as the reserve of genatic information.
→DNA is exclusively responsible for maintaining the identity of different species of organisms over millions of years.
→DNA molecule is capable of self duplication during cell division and identical DNA strands are transferred to daughter cells.
→Actually, the proteins are synthesized by various RNA molecules in the cell but the message for the synthesis of a particular protein is present in 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 too.
James Watson and Francis Crick gave a double strand helix structure for DNA. Two nucleic acid chains are wound about each other and held together by hydrogen bonds are formed between specific pairs of bases. Adenine forms hydrogen bonds with thymine where as cytosine forms hydrogen bonds with guanine.

→Every generation of each and every species resembles its ancestors in many ways.
→These characteristics transmitted from one generation to the next generation.
→It has been observed that nucleus of a living cell is responsible for this transmission of inherent characters also called heredity.
→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).
→Nucleic acids are long chain polymers of nucleotides, so they are also called Polynucleotides.

→"The tertiary structure of proteins represents overall folding of the polypeptide chains ie., further folding of the secondary structure."
→It gives rise to two major molecular shapes viz. Fibrous and globular.
→The main forces which stabilise the 2º and 3º structures of proteins are hydrogen bonds, disulphide linkages, van der Waals and electrostatic forces of attraction.

→Proteins may have one or more polypeptide chains.
→"Each polypeptide in a protein has amino acids linked with each other in a specific sequence and this sequence of amino acids is said to be the primary structure of that protein."
→Any change in the primary structure i.e., the sequence of amino acids creates a different protein.

→"The carbohydrates are stored in animal body as glycogen."
→It is also known as animal starch because its structure is similar to amylopectin and is rather more highly branched.
→It is present in liver, muscles and brain.
→When the body needs glucose, enzymes break down glycogen into glucose.

→The exact spatial arrangement of different -OH groups was given by Fischer after studying many other properties.
→It's configuration is correctly represented as I. So gluconic acid is represented as II and saccharic acid III.

→Monosaccharides are further classified on the basis of number of carbon atoms and the functional group present in them.
→If a monosaccharide contains an aldehyde group it is known as an aldose and if it contains a keto group it is known as ketose.
→Number of carbon atoms constituting the monosaccharide is also introduced in the name. e.g. 3 carbon containing monosaccharide is known as triose and 4 carbon containing monosaccharide is known as tetrose.
→Different types of monosaccharide compounds are given below in table:

Carbon atoms	General term	Aldehyde	Ketone
3	Triose	Aldotriose	Ketotriose
4	Tetrose	Aldotetrose	Ketotetrose
5	Pentose	Aldopentose	Ketopentose
6	Hexose	Aldohexose	Ketohexose
7	Heptose	Aldoheptose	Ketoheptose