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

3.5 Transcription and Translation

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 \/