Chemicals of Life - FAD1001 Biology 1 PDF

CHEMICALS OF LIFE FAD1001 : BIOLOGY 1 Hazwani Mat Saad Academic Room (No.23) Level 3, PASUM Complex [email protected] Tel: 03-79675916  Contents ▪ Introduction ✓Biomolecules definition ✓Elements, compounds ✓Important bonds in b...

CHEMICALS OF LIFE FAD1001 : BIOLOGY 1 Hazwani Mat Saad Academic Room (No.23) Level 3, PASUM Complex [email protected] Tel: 03-79675916  Contents ▪ Introduction ✓Biomolecules definition ✓Elements, compounds ✓Important bonds in biomolecules:- Ionic, covalent, hydrogen, van der Waals ▪ Inorganic compounds: ✓ Water - Structure, properties and functions ✓Acids, bases and buffers ✓Mineral salts ▪ Organic compounds: carbohydrates, lipids, proteins, nucleic acids. ✓ Structure, properties and functions  WATER The Driving Force of All Nature  WATER The molecule that sustains all life Life on Earth began in water, evolved for 3 billion years before colonizing the land. Even terrestrial organisms are tied to water. Most cells are surrounded by water. Cells are about 70–95% water. Water is a reactant in many of the chemical reactions of life.  Structure of water Structure of water Consists of one oxygen and two hydrogen atoms Oxygen is more electronegative than Hydrogen Because oxygen (O) is more electronegative than hydrogen (H), shared electrons are pulled more toward oxygen. – This results in a partial negative charge on the O oxygen and a partial positive charge on the H H hydrogens. + H2O +  polar molecule Water molecule has no net charge but the charge is unevenly distributed http://www.chem4kids.com/files/elements/008_shells.html http://www.chem4kids.com/files/elements/001_shells.html Cont. Structure of water Due to polarity, water molecules attract and form hydrogen bonds with each other H bonds between water molecules are constantly formed, broken and reformed Collective effect of H bonds produce strong force that makes water a stable compound  Liquid water Hydrogen bonds constantly break and reform, allowing liquid water to flow  Properties of water & its biological significance I. Water’s cohesion and adhesion II. High specific heat High heat of vaporization & III. evaporative cooling IV. Lower density of ice V. Water as principal solvent I. Water’s cohesion and adhesion Cohesive forces (cohesion) Attraction between H2O molecules (Hydrogen bonds) produce a surface tension (giving a strong layer/skin to water) Allows insects to walk on water e.g. water strider. Water surface provides a breeding ground and feeding place. Adhesive forces (adhesion) Attraction between H2O and polar substances (Hydrogen bonds) (e.g. container) → make things wet Adhesive + Cohesive forces = Capillary action Tendency of H2O to move in narrow tubes against the force of gravity Cohesion & adhesion Significance Cohesive and adhesive forces act together (capillary action) to allow water to flow upward through plants' vascular system. As water evaporates from the surface of the leaves (transpiration), water molecules that are cohered to the evaporating molecules move upward. The water stays in a tubular shape because it is adhered to the molecules lining the plant's vascular tube. II. High specific heat Definition: amount of heat that must be absorbed or lost by 1 g of substance to change its temperature by 1°C H2O has a high specific heat i.e. 4.2 Joule/1 g/ 1°C Why? Heat used to break H bonds between H2O molecules therefore change in temperature only cause slight change of H2O temperature Significance: Temperature changes is minimized. Water helps maintain a moderate temperature of organisms and environments. https://www.youtube.com/watch?v=mV8SFzzLbHo https://www.youtube.com/watch?v=mV8SFzzLbHo  High heat of vaporization & III. evaporative cooling Definition: the quantity of heat that a liquid must absorb for 1 g of it to be converted from liquid to gas. H2O has a high heat of vaporization (540 cal) because its molecules are held together by hydrogen bonds. Why? Energy is used to break H bonds between H2O molecules so that they can escape as gas (evaporation). Significance: When the H bonds between water molecules is break, they take the heat with them, lowering the temperature of sample.  What happens to oceans, rivers, and ponds when water has a low heat of vaporization? https://www.youtube.com/watch?v=mV8SFzzLbHo  The evaporation of water involves the breaking of hydrogen bonds between water molecules, which take heat energy with them. As a result, the temperature of the water will drop https://www.youtube.com/watch?v=kmmEV4ohSDA Min 1.45 Heat of vaporization Examples and significance Evaporation of water off a surface causes a cooling effect e.g. human sweating, animal panting as the water evaporates off the surface of the skin, it cools down the surface. IV. Lower density of ice most substances are most dense in their solid (frozen) state than in their liquid state but water reaches its highest density at 4ºC as it cools further below 4ºC, density decreases causing ice to float Why? Liquid water expands as it freezes. When water reaches 0ºC, water expels less energy and hydrogen bonding occur water becomes locked into a crystalline lattice, with each water molecule bonded to a maximum of four partners water molecules were arranged farther apart to form the lattice causing ice to expand https://www.youtube.com/watch?v=zRUFzJrDtq0 Water  Three forms of water Biology 9th Edition (2011). Eldra P. Solomon, Linda R. Berg, Diana W. Martin, Linda R. Berg. CENGAGE Lower density of ice Significance during winter oceans and lakes do not freeze solid because when water at the surface become frozen, ice floats forming ice sheets at surface of ponds, lakes, streams. insulates the water below – organisms beneath the ice sheets able to survive V. Water as principal solvent H2O is a polar molecule and are attracted to ions and other polar molecules. → dissolve polar and ionic substances e.g. NaCl Attraction between H2O and ions are stronger than between Na+ and Cl- → NaCl dissolves readily in H2O Water molecules surround the salt molecules and separate the Na+ from the Cl- by forming spheres of hydration around the individual ions and keep ions dispersed in fluid. Water as principal solvent Solutes + Solvent → Aqueous solution (NaCl) (H2O) Significance of Aqueous solution serve as a medium for chemical reactions to take place serve as transport medium in organisms e.g. blood, lymph, digestive tract, xylem & phloem (plants) https://www.youtube.com/watch?v=JGkmGQ89_SE  Exercise Briefly describe the significance of five key properties of water. I. Water’s cohesion and adhesion II. High specific heat High heat of vaporization & III. evaporative cooling IV. Lower density of ice V. Water as principal solvent  Acids, bases & buffers pH 2 pH 7 pH 10  Acid and Base A substance that increases the hydrogen ion Acid concentration in a solution When hydrochloric acid is added to water, hydrogen ions dissociate from chloride ions HCl H+ + Cl− Acid & Base A substance that reduces the hydrogen ion Base concentration in a solution. Some bases reduce the H+ concentration directly by accepting hydrogen ions. NH3 + H+ NH4+ Other bases reduce H+ indirectly by dissociating to OH−, which then combines with H+ to form water. NaOH Na+ + OH− OH− + H+ H2O Acid & Base Chemical processes in the cell are disrupted by changes to the H+ and OH− concentrations away from their normal values. To maintain cellular pH values at a constant level, biological fluids have buffers.  Buffers Substances that minimize changes in pH when acid or base is added by: accepting H+ when [H+] ↑ donating H+ when [H+]  Typically consist of a weak acid and its corresponding weak base. One important buffer in human blood and other biological solutions - carbonic acid which dissociates to yield a bicarbonate ion and a hydrogen ion. Buffers Buffer system in blood [pH 7.3 – 7.5] pH ↑ H2CO3 H CO3¯ Carbonic acid H+ + bicarbonate ion pH  When pH ↑ H2CO3 will dissociate to form H+ & H CO3¯ When pH  H+ & H CO3¯ will combine to form H2CO3 Chemical equilibrium between carbonic acid and bicarbonate acts as a pH regulator. The equilibrium shifts left or right as other metabolic processes add or remove H+ from the solution.  Relation of pH value & [H+] pH  [H+] ↑ pH ↑ [H+]   Mineral salts Required in very small quantities (1 – 2500 mg/day) Used to regulate body processes Minerals are not stored in the body (except iron) Human body requires higher amounts of calcium, phosphorus and magnesium than iodine, iron and zinc e.g. calcium - construction and maintenance of bones  Exercise https://forms.gle/NS482bHzKf77At7h9  Contents ▪ Introduction ✓ Biomolecules definition ✓ Elements, compounds ✓ Important bonds in biomolecules:- Ionic, covalent, hydrogen, van der Waals ▪ Inorganic compounds : ✓ Structure, properties and functions ✓ Acids, bases and buffers ✓ Mineral salts ▪ Organic compounds: carbohydrates, lipids, proteins, nucleic acids. ✓ Structure, properties and functions