UGC 1102 Lecture # 2 Chemical Basis of Life PDF

UGC 1102 - Biology for Non-majors Biology – The Study of Life Questions 1. What are the shared properties that make something “alive”? 2. How do those living things function? 3. When faced with remarkable diversity of life, how do we organize the different kinds of organisms so that we can bette...

UGC 1102 - Biology for Non-majors Biology – The Study of Life Questions 1. What are the shared properties that make something “alive”? 2. How do those living things function? 3. When faced with remarkable diversity of life, how do we organize the different kinds of organisms so that we can better understand them? 4. What biologist ultimately seek to understand-how did this diversity arise and how is it continuing? Characteristics of Living Things What are the shared characteristics that make something “alive”? Characteristics means that the condition is always present to make the particular thing true to its form. Movement/locomotion Reproduction Sensitivity/Irritability Growth/Development Respiration Excretion Nutrition Characteristics of Living Things Non-living things Living Things Move Respire Respond to stimuli Feed Excrete Reproduce Grow Chemical Basis of Life What is life? Life maybe viewed as matter. Atoms are the basic unit of matter. Chemical Basis of Life Elements are the primary constituents of matter Chemical Basis of Life Element are made up of atoms. Each element is distinguished by its atomic number i.e. the number of protons in the nuclei of its atom. Chemical Basis of Life Elements are substances that cannot be broken down into any other substance. There are over 100 elements, some are made in the lab, 92 are naturally present in nature. All elements contained in living matter are called biogenic elements. According to their representation in organisms, the biogenic elements are divided into 3 groups: macrobiogenic, microbiogenic and trace elements. Chemical Basis of Life Macrobiogenic elements – C, O, H, N, S, P, Na, K, Ca, Mg, Cl, Fe. Four of these elements – O, C, H, N – represent up to 95 % of living matter. Macrobiogenic elements have a building function. Microbiogenic elements – Cu, I, Mo, Mn, Zn, Co. The average content of these elements in living organisms is less than 0.1%. Microbiogenic elements have catalytic function, i.e. they are part of enzymes. Trace elements – e.g. Al, As, B, Br, F, Li, Ni, Se, Si, Ti, V. Their content in organisms is less than 0.001 %. As well as microbiogenic elements, trace elements are parts of enzymes and their function is catalytic. Chemical Basis of Life Major element in living and non-living matter Table showing the comparison of elements represented in living and non-living matter Chemical Average Average element representation in representation in living matter (%) non-living matter (%) Carbon 18.5 % 0.18 % Oxygen 65 % 49.40 % Hydrogen 9.5 % 0.95 % Nitrogen 3.2 % 0.63 % Carbon, Oxygen, Hydrogen and Nitrogen Carbon is the basis for all living matter/organisms Carbon has the ability to bond to each other or to atoms of other elements. Molecules are group of atoms bonded together. Macromolecules are the building block of our body. Carbon, Oxygen, Hydrogen and Nitrogen Oxygen & Hydrogen in organisms are present both in the form of organic and inorganic compounds. Additionally, they are part of the basic micro-molecule; water (H2O). Nitrogen, is a component of proteins and nucleic acids. It is also a part of nitrates and ammonium carbonates, which are necessary for the mineral nutrition of plants and also the synthesis of plant proteins Useful Elements Iron (Fe) Aluminum (Al) Gold (Au) Silver (Ag) Copper (Cu) Nickel (Ni) Manganese (Mn) Titanium (TI) Harmful Elements Aresenic (As) Lead (Pb) Mercury (Hg) Reminder Everything is made up of matter Matter is made up of ATOMS Atoms consist of protons, neutrons and electrons Protons, neutrons and electrons are found in elements Elements cannot broken down into anything else. BUT…when bonded together they form molecules (micro & macro) How are elements able to bond? Look at the element Carbon Atomic number=6 To achieve stability carbon shares electrons Drawing Covalent Bonding Covalent Bond Covalent bonds are formed when atoms share electrons in order to satisfy the octet rule. Carbon forms stable bonds with H, O, OH (hydroxyl group). Critical for biological systems to function. Ionic Bonding Ionic bonds are formed when atoms are held together by attraction between opposite charges. E.g. Ionic Bonding vs. Covalent Bonding Ionic Bonding Covalent Bonding Based on the gain or loss of electrons Based on shared valence electrons Results in charged ions No charged ions but maybe polarized Ranges in strength Generally strong Generally between metals and non- Generally between non-metals metals e.g. salt e.g. hydrogen gas Water molecule- Covalent + Hydrogen Bonds Unique characteristics of water Act as a universal solvent Properties of cohesion and adhesion High surface tension High heat capacity Change in density