The Chemistry of Life
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Transcript of The Chemistry of Life
The Chemistry of Life
DP BioMs 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• 1st 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 74-78
• Study hard! Exam next Wed. chapters 1-3!!