(1) French chemist, Jacques Charles first studied variation of volume with temperature, in 1787.
(2) It states that, “The volume of a given mass of a gas is directly proportional to the absolute temperature \[(={{\,}^{o}}C+273)\] at constant pressure”.
Thus, \[V\propto T\] at constant pressure and mass
or \[V=KT=K(t({{\,}^{o}}C)+273.15)\] , (where k is constant),
\[K=\frac{V}{T}\] or \[\frac{{{V}_{1}}}{{{T}_{1}}}=\frac{{{V}_{2}}}{{{T}_{2}}}=K\] (For two or more gases)
(3) If \[t={{0}^{o}}C\], then \[V={{V}_{0}}\]
hence, \[{{V}_{0}}=K\times 273.15\]
\ \[K=\frac{{{V}_{0}}}{273.15}\]
\[V=\frac{{{V}_{0}}}{273.15}[t+273.15]={{V}_{0}}\left[ 1+\frac{t}{273.15} \right]={{V}_{0}}[1+{{\alpha }_{v}}t]\]
where \[{{\alpha }_{v}}\] is the volume coefficient,
\[{{\alpha }_{v}}=\frac{V-{{V}_{0}}}{t{{V}_{0}}}=\frac{1}{273.15}=3.661\times {{10}^{-3}}{{\,}^{o}}{{C}^{-1}}\]
Thus, for every \[{{1}^{o}}\] change in temperature, the volume of a gas changes by \[\frac{1}{273.15}\left( \approx \frac{1}{273} \right)\] of the volume at \[{{0}^{o}}C\].
(4) Graphical representation of Charle's law : Graph between V and T at constant pressure is called isobar or isoplestics and is always a straight line. A plot of V versus \[t({{\,}^{o}}C)\] at constant pressure is a straight line cutting the temperature axis at \[-{{273.15}^{o}}C\]. It is the lowest possible temperature.
(5) At constant mass and pressure density of a gas is inversely proportional to it absolute temperature.
Thus, \[d\propto \frac{1}{T}\propto \frac{1}{V}\] \[\left[ \because V=\frac{\text{mass}}{\text{d}} \right]\]
or \[\frac{{{d}_{1}}}{{{d}_{2}}}=\frac{{{T}_{2}}}{{{T}_{1}}}=\frac{{{V}_{2}}}{{{V}_{1}}}=......=K\]
(6) Use of hot air balloons in sports and meteorological observations is an application of Charle's law.
(1) In 1662, Robert Boyle discovered the first of several relationships among gas variables (P, T, V).
(2) It states that, “For a fixed amount of a gas at constant temperature, the gas volume is inversely proportional to the gas pressure.”
Thus, \[P\propto 1/V\] at constant temperature and mass
or \[P=K/V\] (where K is constant)
or\[PV=K\] or \[{{P}_{1}}{{V}_{1}}={{P}_{2}}{{V}_{2}}=K\] (For two or more gases)
(3) Graphical representation of Boyle's law : Graph between P and V at constant temperature is called isotherm and is an equilateral (or rectangular) hyperbola. By plotting P versus \[1/V\], this hyperbola can be converted to a straight line. Other types of isotherms are also shown below,
(4) At constant mass and temperature density of a gas is directly proportional to its pressure and inversely proportional to its volume.
Thus, \[d\propto P\propto \frac{1}{V}\] \[\left[ \because V=\frac{\text{mass}}{d} \right]\]
or \[\frac{{{d}_{1}}}{{{d}_{2}}}=\frac{{{P}_{1}}}{{{P}_{2}}}=\frac{{{V}_{2}}}{{{V}_{1}}}=.......=K\]
(5) At altitudes, as P is low d of air is less. That is why mountaineers carry oxygen cylinders.
(1) The characteristics of gases are described fully in terms of four parameters or measurable properties :
(i) The volume, V, of the gas.
(ii) Its pressure, P
(iii) Its temperature, T
(iv) The amount of the gas (i.e., mass or number of moles).
(2) Volume : (i) Since gases occupy the entire space available to them, the measurement of volume of a gas only requires a measurement of the container confining the gas.
(ii) Volume is expressed in litres (L), millilitres (mL) or cubic centimetres \[(c{{m}^{3}})\] or cubic metres \[({{m}^{3}})\].
(iii) \[1L=1000\,mL\]; \[1\,mL={{10}^{-3}}L\]; \[1\,L=1\,d{{m}^{3}}={{10}^{-3}}{{m}^{3}}\]
\[1\,{{m}^{3}}={{10}^{3}}\,d{{m}^{3}}={{10}^{6}}c{{m}^{3}}={{10}^{6}}\,mL={{10}^{3}}\,L\]
(3) Mass : (i) The mass of a gas can be determined by weighing the container in which the gas is enclosed and again weighing the container after removing the gas. The difference between the two weights gives the mass of the gas.
(ii) The mass of the gas is related to the number of moles of the gas i.e. moles of gas (n)\[=\frac{\text{Mass in grams}}{\text{Molar mass}}=\frac{m}{M}\]
(4) Temperature : (i) Gases expand on increasing the temperature. If temperature is increased twice, the square of the velocity \[({{v}^{2}})\] also increases two times.
(ii) Temperature is measured in centigrade degree \[({{\,}^{o}}C)\] or celsius degree with the help of thermometers. Temperature is also measured in Fahrenheit \[({{F}^{o}})\].
(iii) S.I. unit of temperature is kelvin (K) or absolute degree.
\[K={{\,}^{o}}C+273\]
(iv) Relation between F and\[{{\,}^{o}}C\] is \[\frac{{{\,}^{o}}C}{5}=\frac{{{F}^{o}}-32}{9}\]
(5) Pressure : (i) Pressure of the gas is the force exerted by the gas per unit area of the walls of the container in all directions. Thus, Pressure (P)\[=\frac{\text{Force(}F\text{)}}{\text{Area(}A\text{)}}=\frac{\text{Mass}(m)\times \text{Acceleration}(a)}{\text{Area}(a)}\]
(ii) Pressure exerted by a gas is due to kinetic energy \[(KE=\frac{1}{2}m{{v}^{2}})\] of the molecules. Kinetic energy of the gas molecules increases, as the temperature is increased. Thus, Pressure of a gas µ Temperature (T).
(iii) Pressure of a pure gas is measured by manometer while that of a mixture of gases by barometer.
(iv) Commonly two types of manometers are used,
(a) Open end manometer; (b) Closed end manometer
(v) The S.I. unit of pressure, the pascal (Pa), is defined as 1 newton per metre square. It is very small unit.
\[1Pa=1N{{m}^{-2}}=1\,kg\,{{m}^{-1}}{{s}^{-2}}\]
(vi) C.G.S. unit of pressure is dynes \[c{{m}^{-2}}\].
(vii) M.K.S. unit of pressure is \[kgf/{{m}^{2}}\]. The unit \[kgf/c{{m}^{2}}\] sometime called ata (atmosphere technical absolute).
(viii) Higher unit of pressure is bar, KPa or MPa. \[1\,bar={{10}^{5}}Pa={{10}^{5}}\,N{{m}^{-2}}=100KN{{m}^{-2}}=100KPa\]
(ix) Several other units used for pressure are,
(1) Gases or their mixtures are homogeneous in composition.
(2) Gases have very low density due to negligible intermolecular forces.
(3) Gases have infinite expansibility and high compressibility.
(4) Gases exert pressure.
(5) Gases possess high diffusibility.
(6) Gases do not have definite shape and volume like liquids.
(7) Gaseous molecules move very rapidly in all directions in a random manner i.e., gases have highest kinetic energy.
(8) Gaseous molecules collide with one another and also with the walls of container with perfectly elastic collisions.
(9) Gases can be liquified, if subjected to low temperatures (below critical) or high pressures.
(10) Thermal energy of gases >> molecular attraction.
(11) Gases undergo similar change with the change of temperature and pressure. In other words, gases obey certain laws known as gas laws.
In addition to air, water, carbohydrates, proteins, fats and mineral salts, certain organic substances required for regulating some of the body processes and preventing certain diseases are called vitamins. These compounds cannot be synthesised by an organism. On the basis of solubility, the vitamins are divided into two groups.
(1) Fat soluble; Vitamin A, D, E and K.
(2) Water soluble; Vitamin B and C.
Name
Sources
Functions
Effects of defficiency
Water soluble vitamins
Vitamin \[{{B}_{1}}\]
(Thiamine or Aneurin)
\[({{C}_{12}}{{H}_{18}}{{N}_{4}}SOC{{l}_{2}})\]
Digestion is the process by which complex constituents of food are broken down into simple molecules by a number of enzymes in mouth, stomach and small intestine. The simple molecules thus formed are absorbed into blood stream and reach various organs.
Raw food may be taken as such or after cooking. It is chewed in the mouth and swallowed when it passes through a long passage in the body called alimentary canal. During this passage it gets mixed with various enzymes in different parts of the alimentary canal. The carbohydrates, proteins and fats are converted into simpler forms which are then carried by blood to different parts of the body for utilization. Digestion of food can be summarized in the following form
(1) \[\text{Polysaccharide}\underset{\left( \begin{smallmatrix} \text{Saliva (mouth);} \\ \text{Pancreatic juice} \\ \text{ (Intestine)} \end{smallmatrix} \right)}{\mathop{\xrightarrow{\text{Amylase}}}}\,\text{Disaccharides (maltose, etc}\text{.)}\underset{\text{(Intestine)}} {\mathop{\xrightarrow{\text{Maltase}}}}\,\text{Glucose}\]Disaccharides
\[\text{Disaccharides (maltose, etc}\text{.)}\underset{\text{(Intestine)}}{\mathop{\xrightarrow{\text{Maltase}}}}\,\text{Glucose}\]
(2)\[\text{Proteins}\underset{\text{(Stomach)}}{\mathop{\xrightarrow{\text{Pepsin/}HCl}}}\,\text{Proteases and Peptones}\underset{\left( \begin{smallmatrix} \text{Chemotrypsin} \\ \text{Pancreatic juice} \\ \text{ (Intestine)} \end{smallmatrix} \right)} {\mathop{\xrightarrow{\text{Trypsin}}}}\,\text{Peptides}\underset{\text{(Intestine)}}{\mathop{\xrightarrow{\text{Peptidases}}}}\,\text{Amino acids}\]
\[\text{Peptides}\underset{\text{(Intestine)}}{\mathop{\xrightarrow{\text{Peptidases}}}}\,\text{Amino acids}\]
(3) \[\text{Fats}\underset{\text{(From liver)}}{\mathop{\xrightarrow{\text{Bile salts}}}}\,\text{Emulsified fat}\underset{\left( \begin{smallmatrix} \text{Pancreatic and} \\ \text{intestine juice} \end{smallmatrix} \right)}{\mathop{\xrightarrow{\text{Lipases}}}}\,\underset{\text{Glycerol}}{\mathop{\underset{+}{\mathop{\text{Fatty acids}}}\,}}\,\]
A cell has small molecules (micromolecules) as well as large molecules (macromolecules). The chemical reactions of a living organism can be divided into main two types
(1) The chemical reactions by which the large molecules are constantly broken down into smaller ones are called catabolism.
(2) The chemical reactions by which the macromolecules are synthesised within the cell are called anabolism.
The two processes i.e., degradation and synthesis are collectively called metabolism. Catabolism reactions are usually accompanied by release of energy whereas anabolism reactions require energy to occur.
The primary energy found in living cells is chemical energy, which can be easily stored, transferred and transformed. For this, the living cells contain a chemical compound called adenosine triphosphate (ATP). It is regarded as energy currency of living cells because it can trap, store and release small packets of energy with ease.
ATP consists of a purine base called adenine linked to a five carbon sugar named ribose which is further attached to three molecules of phosphate.
ATP is energy rich molecule this is because of the presence of four negatively charged oxygen atom very close to each other. These four negatively charged o-atoms experience very high repulsive energy.
\[\text{ATP}\xrightarrow{\text{Hydrolysis}}\underset{\begin{smallmatrix} \text{Adenosine} \\ \text{diphosphate } \end{smallmatrix}}{\mathop{\text{ADP}}}\,+Pi\,\,\Delta H=-30.93\,\,kJ\,\,mo{{l}^{-1}}\]
\[\text{ADP}\xrightarrow{\text{Hydrolysis}}\underset{\begin{smallmatrix} \text{Adenosine} \\ monophosphate \end{smallmatrix}} {\mathop{\text{AMP}}}\,+2Pi\,\,\,\Delta H=-28.4\,\,kJ\,\,mo{{l}^{-1}}\]
ADP can change to ATP in the presence of inoraganic phosphate. This process is called phosphorylation.
Lipids are constituents of plants and tissues which are insoluble in water but soluble in organic solvents such as chloroform, carbon tetrachloride, ether or benzene. They include a large variety of compounds of varying structures such as oils and fats; phospholipids, steroids, etc. Lipids are mainly made of carbon, hydrogen and oxygen. The number of oxygen atoms in a lipid molecule is always small as compared to the number of carbon atoms. Sometimes small amounts of phosphorus, nitrogen and sulphur are also present. They have a major portion of their structure like a hydrocarbon (aliphatic or fused carbon rings). Lipids serve as energy reserve for use in metabolism and as a major structural material in cell membranes for regulating the activities of cell and tissues.
Simple lipids are esters of glycerol with long chain monocarboxylic acids which can be saturated or unsaturated. These are generally called glycerides of fats and oils. Waxes are esters of fatty acids with certain alcohols, not glycerol. Fats and oils have biological importance but waxes have no value as these are not digested.
The functions of triglycerides are the following
(1) They are energy reserves in the cells and tissues of living system. When digested, triglycerides are hydrolysed to fatty acids and glycerol.
(2) Catabolism of fatty acids form acetyl-coenzyme-A. Most of the energy of fatty acids is converted into ATP.
(3) Acetyl coenzyme is the starting material for the synthesis of many compounds.
(4) Fats deposited beneath the skin and around the internal organs minimize loss of body heat and also act as cushions to absorb mechanical impacts.
Another very important class of lipids are the phospholipids. These are polar lipids and like the fats, are esters of glycerol. In this case, however, only two fatty acid molecules are esterified to glycerol, at the first and second carbon atom. The remaining end position of the glycerol is esterified to a molecule of phosphoric acid, which in turn is also esterified to another alcohol. This gives a general structure.
The alcoholic compound linked to phosphoric group may be choline, ethanol, amine, serine or inositol. The phosphate groups forms a polar end, i.e., hydrophilic (water-attracting) and the two fatty acid chains constitute the non-polar tail, i.e., hydrophobic (water repelling). This structure gives the phospholipids good emulsifying and membrane forming properties.
Cell membranes are composed of phopholipids and proteins in about equal, proportion. The phospholipids in the membrane appear to be arranged in a double layer or bilayer in which the non-polar tails face each other, thereby exposing the polar heads to the aqueous environment on either side of the membrane. Proteins found in the membrane are embedded in the mossaic formed by the lipids. Phospholipids facilitate the transport of ions and molecules in and out of the cell and regulate the concentration of molecules and ions within the cell. They provide structural support for certain proteins.
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In every living cell there are found nucleo-proteins which are made up of proteins and natural polymers of great biological importance called nucleic acids.
Two types of nucleic acids are found in biological systems, these are
Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)
The nucleic acid was first isolated by Friedrich Miescher in 1868 from the nuclei of pus cells and was named nuclein. The term nuclein was given by Altman.
(1) Composition : Nucleic acids like proteins and carbohydrates are polymer. The simple units that make up the nucleic acid are called nucleotides. Nucleotides are themselves composed of following three simple molecules.
(i) Nitrogenous base : These are heterocyclic organic compound having two or more nitrogen atoms in ring skeleton. These are called bases because the lone pairs of electrons on the nitrogen atoms make them as Lewis bases. Their structures are given below
(a) Pyrimidine derivatives
(b) Purine derivatives
(ii) Five carbon sugar (Pentose) : In RNA, the sugar is ribose where as in DNA, the sugar is deoxyribose.
Both differ only at carbon atom \[{2}'\] in the ring.
(iii) Phosphoric acid, \[{{\mathbf{H}}_{\mathbf{3}}}\mathbf{P}{{\mathbf{O}}_{\mathbf{4}}}\] : Phosphoric acid forms esters to –OH groups of the sugars to bind nucleotide segments together. A molecule called nucleoside is formed by condensing a molecules of the base with the appropriate pentose. (i.e., Base + Sugar).
A nucleotide results when the nucleoside combined with phosphoric acid mainly at carbon 5' of the pentose. (i.e., Base + Sugar + Phosphoric acid).
This nucleotide is the building block of both DNA and RNA. The nucleic acids are condensation polymers of the nucleotide monomers and are formed by the creation of an ester linkage from phosphoric residue on one nucleotide to the hydroxy group on carbon 3' in the pentose of the second nucleotide. The result is a very long chain possessing upto a billion or so nucleotides units in DNA.
Thus, the formation of a nucleic acid can be summarised in the following general way
RNA nucleotides
Proteins are a class of biologically important compounds. They are crucial to virtually all processes in living systems. Some of them are hormones which serve as chemical messengers that coordinate certain biochemical activities. Some proteins serve to transport the substances through the organism. Proteins are also found in toxins (poisonous materials) as well as in antibiotics. All the proteins are made up of many amino acid units linked together into a long chain. An amino acid is a bifunctional organic molecule that contains both a carboxyl group, \[COOH\], as well as an amine group, \[N{{H}_{2}}\].
The proteins differ in the nature of R-group bonded to \[\alpha -\]carbon atom. The nature of R-group determines the properties of proteins. There are about 20 amino acids which make up the bio-proteins. Out of these 10 amino acids (non-essential) are synthesised by our bodies and rest are essential in the diet (essential amino acids) and supplied to our bodies by food which we take because they cannot be synthesised in the body. The \[\alpha -\]amino acids are classified into the following four types and tasulabed as under,
(5) At constant mass and pressure density of a gas is inversely proportional to it absolute temperature.
Thus, \[d\propto \frac{1}{T}\propto \frac{1}{V}\] \[\left[ \because V=\frac{\text{mass}}{\text{d}} \right]\]
or \[\frac{{{d}_{1}}}{{{d}_{2}}}=\frac{{{T}_{2}}}{{{T}_{1}}}=\frac{{{V}_{2}}}{{{V}_{1}}}=......=K\]
(6) Use of hot air balloons in sports and meteorological observations is an application of Charle's law.
(4) At constant mass and temperature density of a gas is directly proportional to its pressure and inversely proportional to its volume.
Thus, \[d\propto P\propto \frac{1}{V}\] \[\left[ \because V=\frac{\text{mass}}{d} \right]\]
or \[\frac{{{d}_{1}}}{{{d}_{2}}}=\frac{{{P}_{1}}}{{{P}_{2}}}=\frac{{{V}_{2}}}{{{V}_{1}}}=.......=K\]
(5) At altitudes, as P is low d of air is less. That is why mountaineers carry oxygen cylinders.
\[\text{ATP}\xrightarrow{\text{Hydrolysis}}\underset{\begin{smallmatrix} \text{Adenosine} \\ \text{diphosphate } \end{smallmatrix}}{\mathop{\text{ADP}}}\,+Pi\,\,\Delta H=-30.93\,\,kJ\,\,mo{{l}^{-1}}\]
\[\text{ADP}\xrightarrow{\text{Hydrolysis}}\underset{\begin{smallmatrix} \text{Adenosine} \\ monophosphate \end{smallmatrix}} {\mathop{\text{AMP}}}\,+2Pi\,\,\,\Delta H=-28.4\,\,kJ\,\,mo{{l}^{-1}}\]
ADP can change to ATP in the presence of inoraganic phosphate. This process is called phosphorylation.
The alcoholic compound linked to phosphoric group may be choline, ethanol, amine, serine or inositol. The phosphate groups forms a polar end, i.e., hydrophilic (water-attracting) and the two fatty acid chains constitute the non-polar tail, i.e., hydrophobic (water repelling). This structure gives the phospholipids good emulsifying and membrane forming properties.
Cell membranes are composed of phopholipids and proteins in about equal, proportion. The phospholipids in the membrane appear to be arranged in a double layer or bilayer in which the non-polar tails face each other, thereby exposing the polar heads to the aqueous environment on either side of the membrane. Proteins found in the membrane are embedded in the mossaic formed by the lipids. Phospholipids facilitate the transport of ions and molecules in and out of the cell and regulate the concentration of molecules and ions within the cell. They provide structural support for certain proteins.
(b) Purine derivatives
(ii) Five carbon sugar (Pentose) : In RNA, the sugar is ribose where as in DNA, the sugar is deoxyribose.
Both differ only at carbon atom \[{2}'\] in the ring.
(iii) Phosphoric acid, \[{{\mathbf{H}}_{\mathbf{3}}}\mathbf{P}{{\mathbf{O}}_{\mathbf{4}}}\] : Phosphoric acid forms esters to –OH groups of the sugars to bind nucleotide segments together. A molecule called nucleoside is formed by condensing a molecules of the base with the appropriate pentose. (i.e., Base + Sugar).
A nucleotide results when the nucleoside combined with phosphoric acid mainly at carbon 5' of the pentose. (i.e., Base + Sugar + Phosphoric acid).
This nucleotide is the building block of both DNA and RNA. The nucleic acids are condensation polymers of the nucleotide monomers and are formed by the creation of an ester linkage from phosphoric residue on one nucleotide to the hydroxy group on carbon 3' in the pentose of the second nucleotide. The result is a very long chain possessing upto a billion or so nucleotides units in DNA.
Thus, the formation of a nucleic acid can be summarised in the following general way
RNA nucleotides
The proteins differ in the nature of R-group bonded to \[\alpha -\]carbon atom. The nature of R-group determines the properties of proteins. There are about 20 amino acids which make up the bio-proteins. Out of these 10 amino acids (non-essential) are synthesised by our bodies and rest are essential in the diet (essential amino acids) and supplied to our bodies by food which we take because they cannot be synthesised in the body. The \[\alpha -\]amino acids are classified into the following four types and tasulabed as under,
