The chemical molecules which are found in living cells and help in different growth, repair and metabolic activities of cells are called by molecules. The collection of chemical molecules in the cell is called cellular pool. Biomolecules are of two types.
1. Organic molecules (carbohydrates, protein, lipids, nucleic acids, enzymes etc).
2. Inorganic molecules (water, minerals, salts, etc).
Carbohydrates:
Carbohydrates are polyhydroxy aldehyde(-CHO) or ketone(C=O) derivatives. They are also called saccharides or sugar. These are the major sources of energy. They contain carbon, hydrogen and oxygen. The general formula of carbohydrates is CnH2nOn.
Types of carbohydrate
Monosaccharides:
Carbohydrates containing single sugar molecules. They have carbon atoms of 3 to 7. It is soluble in water and sweet in taste. Common examples are: Glucose, fructose, Galactose, ribose, deoxyribose, glyceraldehyde etc.
Oligosaccharides:
Sugar containing a chain of 2 to 10 molecules of monosaccharides is called oligosaccharides.
Disaccharides:
Sugar containing two molecules of monosaccharides is called disaccharides. They are soluble in water and sweet in taste. These are joined by glycosidic bonds. Common disaccharides are:
Glucose+Glucose= Maltose
Glucose+Galactose= Lactose
Glucose+Fructose= sucrose
Polysaccharides:
It is the polymer of monosaccharides. Many monosaccharides are joined together by glycosidic bonds. They are tasteless, insoluble in water but soluble in organic solvent. Common polysaccharides are: starch, glycogen, cellulose.
Importance of carbohydrates
1. Carbohydrates are an excellent source of energy.
2. Glucose and fructose are quick sources of energy, thus they are also called as respiratory fuel.
3. Ribose and deoxyribose sugar are the components of RNA and DNA respectively.
4. They form Fats and amino-acids.
5. Cellulose, hemicellulose, chitin etc are the components of cell walls.
6. Starch and glycogen are the storage food material of plants and animals.
7. Some carbohydrates help to lubricate skeletal joints.
8. Fibres present in carbohydrates help to control constipation.
9. Papers are formed by cellulose.
Lipids
Lipids are the group of fat and fat like biomolecules containing C, H and O. The amount of O2 in lipids is less than carbohydrate. It is an energy rich subtract. The lipids are the esters of fatty acid and alcohol. They are of 3 types:
1.) Simple lipid
2.) Compound lipid
3.) Derived (Complex) lipid
Simple lipids: they are the ester of fatty acid and alcohol. They are fat, oil, wax etc.
1. Fats: Fats are esters of fatty acid and glycerol and solid at room temperature. They contain saturated fatty acid.
2. Oils: They are the ester of fatty acid and glycerol but liquid at room temperature. They contain unsaturated fatty acid.
3. Wax: They are the esters of fatty acid and alcohol other than glycerol. They contain saturated fatty acid.
Compound lipids: They are the esters of fatty acid and alcohol with additional groups. For example
● Glycolipid = lipid + carbohydrates
● Phospholipid= lipid + phosphate
● Lipoprotein = lipid + protein
Derived lipids:
Those lipids which are obtained by the hydrolysis of simple and compound lipids are called derived lipids. Eg., Cholesterol, ergosterol, alcohol of large molecules etc.
Glycerol: It is trihydric alcohol and can react with three molecules of fatty acid to form lipids.
Fatty acids: Hydrocarbons that end in a carboxylic group (- COOH) is called fatty acid.
Function of lipid:
Amino Acid and Proteins:
Amino acids are organic compounds having an acidic carboxylic group(-COOH) and basic group(-NH2). Such compounds have acidic groups and basic groups called “amphoteric “. Amino acids are small molecules containing C,H,O,K and P. There are 20 types of amino acids in which 8 are essential to our body which must be supplied by diet and the remaining 12 are synthesized inside the cells. These amino acids are called the building block of protein.
Amino acids are the monomers of protein. Each amino acid consists of an amino group (NH2) and carboxylic group (-COOH). They are colourless, crystalline solids, soluble in water and insoluble in solvent.
Peptide bond : When two amino acids are joined together by the union of the carboxylic group of one amino acid with the amino group of another amino acid the bond is formed, which is called peptide bond.
Function of Amino Acids:
1.) They take part in synthesis of protein.
2.) They form vitamins, hormones, enzymes,etc.
3.) When the amino group (NH2) of amino acids are removed, the remaining hydrocarbon chain can form carbohydrates.
Protein
Proteins are the polymers of amino acids. Proteins are made up of 20 different naturally occurring amino acids. Amino acids are linked by peptide bonds. The NH2 group of one amino acid reacts with the -COOH group of other amino acids and the peptide bond is formed by releasing water. Proteins have different structures.
1. Primary Structure : The simple linear structure of protein is called primary structure. E.g. Insulin, ribonuclease.
2. Secondary Structure : It is formed by twisting of primary structure. E.g. Protein of hair.
3. Tertiary Structure : It is formed by further coiling and infolding of secondary structure of protein indefinitely. The folding is a globular shape and is a 3-dimensional structure. E.g.Myoglobin.
4. Quaternary Structure: It is formed due to polymerization of tertiary structure of protein. E.g. Haemoglobin.
On the basis of constituent, Protein are of following types:
1.) Simple Protein : They bear only amino acids.
2.) Conjugate Protein : They bear a prosthetic group with amino acids. E.g Phosphoprotein= Phosphatase + Protein Glycoprotein= Glucose + Protein Lipoprotein= Lipid + Protein Nucleoprotein= Nucleic acid + Protein
3.) Derived Protein : These are formed by hydrolysis , denaturation and breakdown of simple and conjugated protein. E.g. Fibrinogen.
Function of Protein :
1.) Proteins are the source of energy. (1gm=5.6Kcal)
2.) Many proteins act as a structural protein and take part in building and repairing body tissue.
3.) It acts as an enzyme, which regulates life processes.
4.) It regulates the growth and development of organisms.
5.) Some proteins are antibodies which develop immunity.
6.) Proteins like thrombin and fibrinogen help in blood clotting.
7.) It provides strength to skins and bones.
8.) Growth hormones which are proteins control the metabolism.
Nucleic acids
Nucleic acid is the polymer of nucleotides (polynucleotides). It is the genetic material of all living organisms. Nucleic acids are DNA and RNA. Each nucleotide consists of three components i.e., Nitrogen base, pentose sugar and phosphoric acid.
1. Nitrogen bases: Nitrogen bases are heterocyclic aromatic compounds found in nucleotides. There are two types of nitrogen bases i.e.,
a. Purine: Purines are nine members of a double ring of carbon-nitrogen. Two rings are attached at 4’ and 5’ positions and contain nitrogen at 1, 3, 5, 9 positions. Eg., A, G.
b. Pyrimidines: Pyrimidines are 6 members of a single ring of carbon-nitrogen. E.g. C,T,U. Nitrogen is found at 1 and 3 positions.
2. Pentose sugar: 5- carbon sugar found in nucleic acid is called pentose sugar. There are two types of pentose sugar.
a. Ribose sugar: It is found in RNA
b. Deoxyribose sugar: It is found in DNA.
. Phosphoric acid: It contains phosphate groups and forms the backbone of nucleic acid. It helps to combine nucleotides forming phosphodiester bonds.
Deoxyribo-nucleic acid (DNA)
DNA is the polymer of deoxyribonucleotides. The large number of deoxyribonucleotides are joined by phosphodiester bonds. James Watson and Francis Crick (1953) gave the double helix model of DNA for which they were awarded the Nobel prize in 1962.
Structure of DNA:
1. DNA is the polymer of deoxyribonucleotides.
2. It is a double stranded, helically twisted structure.
3. These two strands are antiparallel i.e., one strand runs in 3-5 direction but other strand runs in 5- 3 direction.
4. The distance of one complete turn is 34A0 and has 10 pairs of N-bases.
5. The distance between two pairs of N-bases is 3.4A0
6. The diameter between two helix is 20A0 .
7. The complementary N-bases of two strands of DNA are held by weak H-bond i.e. two H-bonds in A=T and three H-bonds in G and C (G = C).
8. The sugar and phosphate of DNA helix are joined together by phosphodiester bonds. S-P-S forms the backbone of DNA.
9. Bond between N-base and pentose sugar is a glycosidic bond.
Functions of DNA
1. DNA is genetic material and transmits the characters from parents to offspring.
2. DNA has autocatalytic and heterocatalytic functions. DNA forms DNA by replication is called the autocatalytic function of DNA. DNA- DNA
3. DNA forms RNA by transcription process. Then RNA forms protein by translation process. These are the heterocatalytic functions of DNA. DNA-RNA-Protein.
4. It controls all the metabolic activities of cells by synthesis of protein.
5. Changes in sequence and number of nucleotides produce mutation which results in evolution.
6. It synthesizes RNA and protein.
7. It controls the development of organisms.
RNA:
RNA is a single stranded polyribonucleotide. Each ribonucleotide consists of N-base, ribose sugar and phosphoric acid. N-bases are A,U,G,C. Large numbers of nucleotides are joined together by phosphodiester bonds. There are three types of RNA i.e.,
1. Ribosomal RNA (rRNA): It represents 70-80% of total RNA. It is the major component of ribosomes. It is synthesized from the nucleolus and helps in protein synthesis.
2. Messenger RNA (mRNA): It represents about 8-10% of total RNA. It is formed from nuclear DNA. Thus, it carries genetic information from DNA.
3. Transfer RNA (tRNA): It represents about 10-15% of total RNA. It acts as an amino acid acceptor. It forms a clover leaf like structure.
There are five different sites of RNA i.e.,
1. Acceptor site: 3’ of tRNA has CCA-OH which carries amino acid called acceptor site.
2. DHU (Dihydrouridine) binds for aminoacyl synthetase enzymes.
3. Anticodon loop: Among the 7 bases in anticodon 3 bases complementary with codon of mRNA.
4. T C loop: It is the binding site of ribosomes.
5. Extra arm: It lies in between anticodon loop and T C.
Mineral Nutrition
The process by which organisms obtain substances for their nourishment is called nutrition. The chemical substances that provide an arrangement are called nutrients. Green autotrophic plants utilise inorganic substances(CO2 and H2O) to make glucose molecules. These glucose molecules are then used for the formation of starch, cellulose, fat, amino acids etc. Fertilizers are also made up of inorganic chemical compounds necessary for plants.
Most of the elements are absorbed from the soil and from mineral nutrition of the plant. All plants need these inorganic minerals to make organic molecules like protein, lipid, nucleic acid, vitamins etc. Minerals are absorbed along with water from the soil through root hairs. The nutrients or elements which are essential for healthy growth of the plant are called essential nutrients or essential elements. Its role is
● An essential element is necessary for normal growth and reproduction.
● The requirements of the element are very specific and it cannot be replaced by another element.
● The element is directly involved in the nutrition of a plant.
The essential elements that required in large quantities is called macronutrients for example C, H, O, N, P, K, Ca, Mg, S. the essential elements that required in small quantities is called micronutrients for example Mo, Mn, B, Co, Fe, Zn, Cl.
Functions and deficiency symptoms of various elements:
Nitrogen, N:-
1. Required for the synthesis of amino acids, proteins, vitamins, nucleic acid, organic compounds and hormones etc.
2. Helps in the synthesis of chlorophylls. Deficiency of nitrogen causes stunted growth, chlorosis in leaves, reduced flowering etc.
Phosphorus, (P)
1. Synthesis of nucleic acid, ATP and proteins.
2. As phospholipids in membranes.
3. Constituents of bone and tooth enamel.
4. Required for synthesis of phospholipid NAD, NADP. Deficiency of phosphorus causes poor growth of the root, leading to premature leaf fall.
Potassium,(K)
1. Activities about 40 enzymes.
2. Anion - cation balance in cell.
3. Brings opening and closing of stomata.
4. Helps in turgidity of cells.
5. Maintenance of electrical potential across the membrane.
6. Conduction of nerve impulse.
Deficiency of potassium causes stunted growth yellow and shrivelled leaf margin.
Calcium,(Ca)
1. Present age calcium pectate in the middle lamella of the cell wall.
2. Activates the enzyme for root and shoot tip growth.
3. Helps in cell division and cell enlargement.
4. Strength and rigidity to bones and teeth.
5. Form exoskeleton of invertebrates.
6. Used as fertilizer in bone dust.
7. Forms shells of molluscs. Deficiency of calcium causes chlorosis of young leaves, death of the apical bud, poor root growth.
Magnesium, (Mg)
1. Helps in chlorophyll formation.
2. Important for synthesis of fat.
3. Essential for binding components of ribosomes.
4. Rigidity to bones and teeth.
5. Cofactor of enzymes like ATPase. Deficiency of magnesium causes chlorosis, which leads to necrosis.
Sulphur, (S)
1. Constituents of some amino acids.
2. Present in coenzymes A biotin, vitamins.
3. Increases in root development.
4. Nodule formation in legumes.
5. Synthesis of protein keratin.
6. Synthesis of organic compounds like coenzyme A.
Deficiency of sulphur causes chlorosis in young leaves.
Sodium (Na)
1. Similar functions as potassium.
2. Cofactor in photosynthesis and respiration.
3. Balance of anion- cation and osmotic balance of cellular fluids.
Iron(Fe)
1. Needed for the synthesis of chloroplast protein.
2. Is a constituent of ferredoxin and cytochromes.
3. Oxygen carrier as a heme in hemoglobin and myoglobin.
4. Electron carriers in cytochromes.
5. Synthesis of chlorophyll.
Deficiency of iron leads to interventional chlorosis in young leaves, anaemia in animals.
Manganese (Mn)
1. Helps in chlorophyll formation, nitrogen metabolism.
2. Activates carboxylase enzymes.
3. Decarboxylation reactions during respiration.
4. Oxidation of fatty acid.
5. Along with phosphatases for bone development.
Deficiency of manganese causes chlorosis and necrosis in leaves and inter venal zones.
Cupper(Cu)
1. Components of oxidase enzyme and plastocyanin.
2. Involves in electron transport in photosynthesis.
3. Helps in production of melanin.
4. Electron carrier in cytochrome oxidase.
Deficiency of copper causes necrosis at the tip of young lives and then the margins. Dieback of shoots reduces absorption.
Molybdenum(Mo)
1. Required for nitrogen fixation.
2. Activates the enzyme nitrate reductase.
3. Helps in the formation of protein.
Deficiency of molybdenum causes multi and necrosis in leaves, abscission of flowers, fall in ascorbic acid content of the plant.
Boron, (B)
1. Increases the uptake of water and calcium.
2. Essential for meristem activity and growth of pollen tube.
3. Involved in translocation of carbohydrates.
Deficiency of boron causes death of root and shoot, reduced flower production, thickened leaves and that curl.
Zinc (Zn)
1. Component of indole acetic acid IAA.
2. Activates dehydrogenase and carboxylase enzymes.
3. Activates protein synthesis.
Deficiency of zinc causes reduction in internode length, rosette type growth, and little leaves.
Chlorine (Cl)
1. Essential for oxygen evolution in photosynthesis.
2. Anion cation balance in cells.
3. Proper hydration in tissues.
4. Form a major component of blood plasma.
5. Help in exchange of gas in tissue during respiration.
Deficiency of chlorine causes chlorosis and necrosis in leaves, retards growth, and affects the process of photosynthesis.
Hope this will help you a lot.
For more, be in touch with eduguidenep.blogspot.com
Post a Comment