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The Chemistry of Life. DP Bio Ms Wilson 9/12. 3.1 Chemical elements and water. 4 elements most commonly found in living things (as we know them!) Carbon Hydrogen Oxygen Nitrogen What else do living things need? Why?. Water. Thermal properties
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The Chemistry of Life DP Bio Ms Wilson 9/12
3.1 Chemical elements and water • 4 elements most commonly found in living things (as we know them!) • Carbon • Hydrogen • Oxygen • Nitrogen • What else do living things need? Why?
Water • Thermal properties • High specific heat (can absorb or release a lot of heat without changing temp – temp stabilizer) • High heat of vaporization (cooling mechanism) • Cohesive properties • Forms droplets • Surface tension (Jesus Christ lizard) • Moves as a column in plants • HSH and HHV • Solvent properties • Glucose, amino acids, fibrinogen and hydrogencarbonate ions (transport CO2) in blood
3.2 Carbs, lipids and proteins • Carbohydrates – monosaccharides • Lipids – glycerol and fatty acids • Proteins (polypeptides) – amino acids • Nucleic acids – nucleotides • Why are models of these molecules used? What do the molecules actually look like?
Functions of carbs: • Animals: • Glucose (mono-) • Chemical fuel for cell respiration • Lactose (di-) • Makes up some of the solutes in milk • Glycogen (tri-) • Stores glucose in liver and muscles • Plants: • Fructose (mono-) • Found in many fruits • Sucrose (di-) • Often transported from leaves of plants to other locations in plants by vascular tissue • Cellulose (tri-) • One of the primary components of plant cell walls
Lipids • Why are they important? • Insulation • Adipose cells hold more or less • Energy storage – think about this primitively • Phospholipid – what is that?
Hydrolysis and Condensation • Hydrolysis: water “splitting” as part of reaction • Figure 3.7
Condensation • Condensation: water is a product • Figure 3.8
3.3 DNA Structure • Nucleotide: a phosphate group O=P, a deoxyribose sugar and a nitrogenous base • 4 Nitrogenous bases • Adenine • Thymine • Guanine • Cytosine • Nucleotides are covalently bonded • Complementary pairs are hydrogen bonds (T and C are much smaller than A and G) • C-----G • A-----T • Check out heinemann.co.uk/hotlinks; ex code 4242P and click on Weblink 3.4
3.4 DNA Replication • Hydrogen bonds undone so DNA can be copied • Helicase is an enzyme that does this
Formation of 2 complementary strands • Free nucleotides also present – can bond to end of strand • These covalent bonds are catalyzed by DNA polymerase
Transcription • Produces RNA using free nucleotides in nucleoplasm • Only 1 strand of DNA is copied • mRNA is single stranded and shorter than DNA (only 1 gene) • DNA has thymine and deoxyribose • RNA has uracil • Figure 3.15 \/