Unit C Environmental Chemistry

Topic 1: Role of Substances The most common chemical elements in living things are C, O and H ORGANIC COMPOUNDS Compounds that contain C Exceptions: CO2, CO INORGANIC COMPOUNDS Compounds that do not contain C

Hydrochloric acid (HCl) Classify each substance below as organic or inorganic Key question: Does the substance contain carbon? Substance Organic or Inorganic? Oxygen Distilled water Sugar Carbon dioxide Motor oil Hydrochloric acid (HCl) Rust Glass Fat

Types of Organic Molecules Carbohydrates Composed of C, H and O Used to provide instant energy Soluble in water Ex: Sugar (C6H12O6) Starch

Lipids Composed of C, H and O Used to store energy; saved for use at a later time Insoluble in water Eg. Oils and fats

Proteins Composed of C, H, O and N Made of units called amino acids Each protein has its own number & arrangement of amino acids Used for growth and repair; are a source of energy

Nucleic Acids Made up of phosphates (P), ribose (sugar – C, H & O) and N-containing bases (A, T, G, C) Largest and most complicated molecules found in living things Eg. DNA and RNA

Nutrients Elements and compounds that are needed for living, growing and reproducing 2 main types: Macronutrients Needed in relatively large amounts Include compounds that contain C, H, O, N, P, K, Mg, Ca and S

Micronutrients Needed in relatively small amounts Include vitamins and minerals Optimum amounts Amount of a substance that provides an organism with the best health Too much or too little can lead to problems

Nutrient Use in plants Use in animals N -composition of proteins, DNA and chlorophyll -leaf and stem growth -composition of proteins and DNA -growth and repair of tissues P -root and flower growth -cellular respiration and photosynthesis -part of DNA -composition of bones, teeth and DNA -many metabolic reactions K -early growth -disease resistance -chlorophyll production -muscle contraction -nerve impulses Mg -composition of chlorophyll -photosynthesis -composition of bones and teeth -absorption of calcium Ca -cell wall structure -cell division -muscle and nerve function S -production of fruits -protein synthesis -enzyme activation -detoxification

What macronutrient are the plants missing? What can the farmer do? A farmer noticed that his crops are not growing as well as they have in past years The lower leaves are showing a distinct yellow striping and the plants are not as tall as they should be He has been applying large amounts of P and K fertilizer, expecting to get high yields from his crops Soil test show low levels of Mg and high levels of K. High levels of K can interfere with the absorption of Mg by the plant What macronutrient are the plants missing? What can the farmer do?

Selenium (Se) is required in trace amounts Prevents cellular damage Strengthens immune system Too little More susceptible to cancer, heart disease Keshan disease (enlarged, poor functioning heart) Crohn’s disease Too much Selenosis Nasea, Fatigue Nerve damage Cirrhosis of liver

How Organisms Take in Substances

Animals Obtain nutrients from food Ingestion Process of taking food into our bodies Digestion Food is broken down into smaller pieces Think back to chemistry…how can you speed up a reaction?

Food is broken down Mechanically Mouth & teeth Chemically Stomach and small intestine Hydrolysis Breakdown of a substance using water Eg. C12H22O11 + H2O → 2 C6H12O6 Nutrients are absorbed through cell membranes and into the bloodstream Blood carries nutrients to other cells

Plants Obtain their nutrients from the soil and air Diffusion Passive process Does not require energy Movement of molecules from an area of higher concentration to an area of lower concentration

Osmosis Diffusion of water across a semi-permeable membrane Water moves from an area of high concentration to an area of low concentration Passive process