Lecture 4 Chemicals of Life

Biochemistry Biochemistry is the study of chemicals and chemical reactions/processes that occur in living organisms. PhysicsChemistryBiology Biochemistry Medicine Genetics Food Industry Agriculture Microbiology Diagnosis New drugs Antibiotics Herbicides Pesticides Yogurt Sugar

Chemical Reactions Respiration : nutrients + oxygen to make carbon dioxide and energy. Plants absorb the carbon dioxide, along with light, producing oxygen, carbohydrates (sugars), in the process of transpiration, which involves Water, Electrons and Light.

Elements All matter made up of elements. There are 3 states of matter – solid, liquid and gas. Properties –Structure –Metal/non-metal –Acid/Alkali –Bonding Periodic Table

Basic Chemistry Some atoms prefer to stay by themselves. Some join other atoms to form covalent bonds. Some join other with atoms from other elements. Some atoms charged so when they join form ionic compounds. When atoms join by covalent bonding they form molecules When atoms join by ionic bonding they form ionic compounds. When atoms join by metallic bonding they form alloys Bond = force that holds atoms together

Elements covalent molecule = Non-metal + non-metal ionic compound = Metal + non-metal alloy= Metal + metal

Definitions An element is a substance not broken down chemically. Can exist as single atoms or molecules. A molecule is made of two or more atoms ( same or different elements) joined by covalent bond. A compound is a substance made of 2 or more different elements joined by covalent (molecules) or ionic bonds (ionic compounds). An ionic compound is made up of 2 or more charged atoms joined by an ionic bond.

Energy is the Key to Survival If we do not breathe or eat we will not survive. The processes of respiration and nutrition generate ENERGY. Living organisms need energy to function. Law of Conservation Light, chemical, heat, electrical, mechanical, and sound energy.

Chemicals of Life Living organisms exist as more than just compounds. Living organisms use same basic inorganic elements as non-living matter, but differ in combination and complexity. Carbon based – organic molecules Water

Organic Molecules Only produced by living organisms? Carbon based. 2 million organic molecules known or have been synthesised. Used to make more complex molecules. Chains of organic molecules. Functional groups. Structure.

Water Most of the properties of water are unique. Uniquely suited to support of life High specific heat, high heats of fusion, condensation, high surface tension, liquid at most global temperatures, density characteristics, capillarity, adhesion, cohesion, and is a good solvent. What are the physical characteristic of the water molecule that results in most of these attributes.

Structure of Water Water is a polar molecule. O H H O H H + + hydrogen bond

Result of polar nature It behaves as if it were "sticky" with respect to any other electrically charged object or particle, including other water molecules. Water molecules tend to stick together through the formation of hydrogen bonds. Individually unique weak but collectively strong

Effects of Hydrogen Bonds Water is a good solvent Water has a high heat capacity Water has a high heat of vaporization Water high heat of fusion Water has a unique density and freezing properties Water has high surface tension and cohesion properties. Water is a reagent.

Water as a Solvent In general, polar molecules tend to mix well, or dissolve, in each other. E.g NaCl and water Non-polar compounds are insoluble in water. Non-polar compounds are soluble in non- polar solvents.

High Heat Capacity A large increase in heat energy results in a small raise in temperature. Breaking H-bonds. Temperature changes minimised in water Constant external environment.

High Heat of Vaporisation Lots of energy required to make molecules evaporate / boil away into a gas. Loss of energy from surroundings. Cooling effect.

High Heat of Fusion Energy required to melt a solid. Because of high heat capacity, a large amount of heat energy is needed to thaw ice. Liquid water needs to lose a large amount of heat energy to freeze. Ice crystals in cells dangerous. Water at temperature < 4 O C becomes less dense. Ice floats, forms insulation in extreme conditions.

High Surface Tension and Cohesion Cohesion is the force whereby individual water molecules stick together. Held together by hydrogen bonds. These cohesive forces produce another force at the surface of water called surface tension.

Water as a Reagent Source of essential elements. Used in photosynthesis as a source of hydrogen: CO 2 + H 2 O light/electrons (CH 2 O)n + O 2 Used within a cell during hydrolysis to make energy: ATP + H 2 O hydrolysis ADP + P + energy

Biochemical Reactions Cell respiration in eukaryotes is made up of two biochemical processes: oxidation and reduction. Oxidation is the loss of electrons and reduction is the gain.

Why learn about the Chemicals of Life? Use organic and inorganic molecules to make building blocks. Building blocks for macromolecules Carbohydrates/Proteins/Lipids and DNA. Understand structure and function.

Bio101 Assignment 2: Biochemistry 1. What is the valency of each atom in the following:- a) Potassium, K b) Fluorine, F c) Glyceraldehyde C 3 H 6 O 3 2. What type of bonds would the following elements form with another atom or atom(s) of other elements:- a) Calcium, Ca b) Aluminium, Al c) Carbon, C + Oxygen, O 3. What functional groups are present in the following molecule of glyceraldehydes:- 4. If all matter is made up of the same elements, how are living organisms different from non-living matter?