Topic 3.1 Chemical elements and water

Introduction Organic chemistry is the chemistry of carbon compounds. Biochemistry is the branch of organic chemistry which attempts to explain the chemistry of living organisms. Fortunately, biochemistry is rather similar from one organisms to another. The majority of organic molecules hound in living organisms can be classified into one of four types: Carbohydrates Lipids Proteins Nucleic acids

Elements found in living organisms It can be argued that any living organisms is merely a collection of elements on the form of atoms, ions, and molecules. The four most common elements found in living things: Carbon Hydrogen Oxygen Nitrogen These elements are found in the molecular structure of all carbohydrates, proteins, lipids, and nucleic acids

Elements found in living organisms In addition, living organisms contain a variety of other elements which are extremely important, but are less common. Element Example role in plants Example role in animals Example role in prokaryotes Sulfur In some amino acids Calcium Co-factor in some enzymes Co-factor in some enzymes and component of bones Phosphorus Phosphate groups in ATP Iron In cytochromes In cytochromes and in hemoglobin Sodium In membrane function In membrane function and sending nerve impulses

Structure of water Water is the solvent of life. Virtually all cells have water within (cytoplasm) and water in the surrounding environment (intercellular fluid, pond water, etc)

Structure of water In a water molecule two hydrogen atoms form single polar covalent bonds with an oxygen atom. Because oxygen is more electronegative, the region around oxygen has a partial negative charge. The region near the two hydrogen atoms has a partial positive charge. A water molecule is a polar molecule with opposite ends of the molecule with opposite charges

Materials Water has a variety of unusual properties because of attractions between these polar molecules. The slightly negative regions of one molecule are attracted to the slightly positive regions of nearby molecules, forming a hydrogen bond. Each water molecule can form hydrogen bonds with up to four neighbors.

Properties of water and living organisms Thermal properties Water has thermal properties that are important to living things. High Specific Heat High heat of vaporization

Properties of water and living organisms High Specific Heat This means water can absorb or give off a great deal of heat without changing temperature greatly Think of a body of water on a very cold night; even though the air may be very cold, the body of water is relatively stable in temperature All living things are composed of a great deal of water and thus you can think of your water content as a temperature stabilizer

Properties of water and living organisms High heat of vaporization This means water absorbs a great deal of heat when it evaporates. Many organisms use this as a cooling mechanism. Internal body heat results in perspiration, the perspiration then evaporates from your skin. Much of the heat that turned the water molecules from liquid phase to the vapor phase came from your body and thus sweating not only makes you feel cooler, it really does lower your temperature

Properties of water and living organisms

Properties of water and living organisms

Properties of water and living organisms