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 \/

Genetic Code Written in 3’s…every 3 base pairs can code for any of the 20 amino acids (Called a codon) mRNA: a comp. copy of DNA, can code for a gene rRNA: makes up ribosomes with ribosomal protein tRNA: transfers 1/20 aa’s to ribosome, contains anticodon to mRNA TRANSLATE TRANSLATION with a partner!

3.6 Enzymes Enzymes: proteins (long chain of aa’s) forming very specific shape; “–ase” Require a certain temperature unless they denature (sometimes permanent) Require pH 7 or lower Lactose intolerance is… – Inability to produce lactase (mono’s are absorbed more easily) – Pills for lactase available – Very very common

3.7 Cell Respiration Used by all cells to produce ATP 1 st step: Glycolysis – Glucose enters cell, eventually becomes pyruvate, 2 ATP molecules needed for glycolysis (net gain of 2) Anaerobic respiration – AKA fermentation: yeast undergoes glycolysis to produce pyruvate, CO2 and ethanol – Lactic acid fermentation: when exercise exceeds O2 supply, glycolysis, pyruvate to lactate and back with O2 available Aerobic is most efficient (because glucose is completely oxydized) – Mitochondria go through glycolysis and get 2 pyruvate molecules which are metabolized in mitochondria Pgs 70-73

3.8 Photosynthesis Light to energy in just plant cells? Read about photosynthesis in your book on pgs Study hard! Exam next Wed. chapters 1-3!!