Which elements are the most commonly occurring in living
organisms?
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Research: uses of these elements, in plants/animals or both
Hydrogen ions Oxygen Nitrogen Iron Calcium Phosphorous Sulphur
Sodium & Potassium
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ElementFunction Hydrogen ionsActive transport (photosynthesis
& respiration), pH is a measure of the activity of dissolved H+
ions ( low pH = high conc. H+ions pH 1-6. High pH = low conc. H+
ions pH 8-14 ) OxygenAerobic respiration, oxidative phosphorylation
(last stage in respiration), other oxidation reactions (releasing
energy from ATP) NitrogenProduction of amino acids, AA form
proteins, used in chorlophyll IronHaemoglobin (oxygen binding RBC),
producing chlorophyll, photosynthesis (ferrodoxin)
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Calcium Bones, teeth, calcium carbonate (exoskeletons),
synaptic transmission (neural pathways), muscle contraction.
PhosphorousPhospholipid bilayer of membranes SulphurFound in some
amino acids. Also found in chemosynthetic bacteria (deep sea vents)
chemoautotrphs. Sodium & PotassiumSodium-potassium pumps
(active transport across membranes)
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What do you know about elements? They form compounds! Carbon
atoms can form FOUR covalent bonds = diversity of stable compounds.
Four main categories of carbon compound are: 1. Carbohydrates 2.
Lipids 3. Proteins 4. Nucleic acids
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Testing for these groups GroupTestPositive result
CarbohydrateFew drops of iodine ProteinSmall amount of biuret
solution Reducing sugars (carbohydrate) Small amount of benedicts
solution plus heat LipidRub a small amount of the sample on
paper
What am I? 1. I dont react with biuret or iodine but in the
presence of benedicts I turn red. 2. I will not dissolve in water,
iodine has no effect on me. 3. I colour with biuret, but not
benedicts.
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Molecular Drawings! You need to be able to draw and recognize:
Glucose Ribose A saturated fatty acid Generalized amino acid Pages
65/66
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What is this? Amino acid!
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Mono, Di or Poly? Maltose Disaccharide
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What is this? Saturated fatty acid
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Mono, Di or Poly? Glycogen Polysaccharide
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What is this? Ribose
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What is this? Unsaturated fatty acid
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Mono, Di or Poly? Fructose Monosaccharide
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Glucose What is this?
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How are you going to remember these structures?
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Can you SPOT the difference?
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What are these? Phospholipid Triglyceride Steroid
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Important groups to remember Hydroxyl group Amine group Methyl
group Carboxyl group
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Define the following terms Metabolism The web of all enzyme
catalysed reactions in a cell or organism. Anabolism The synthesis
of complex molecules from simpler molecules including the formation
of macromolecules from monomers by condensation reactions.
Catabolism The breakdown of complex molecules into simpler
molecules including the hydrolysis of macromolecules into
monomers.
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The connection of small molecules to form larger molecules
releasing water. + Water Condensation reactions
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Example of a condensation reaction. Peptide bond
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Example Qu. Answer: III
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Hydrolysis Addition of water, breaking bonds between molecules
+ Water
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Example Glycosidic bond
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Example Qu.
Slide 34
Past question 1. Outline the role of condensation and
hydrolysis in the relationship between amino acids and dipeptides
(4) ANSWER Diagram of a peptide bond drawn Condensation/dehydration
synthesis: water produced (when two amino acids join) Hydrolysis:
water needed to break bonds Dipeptide amino acids (hydrolysis
occurs) amino acids dipeptide (condensation occurs)
Slide 35
What do these have in common? Paul Joseph Barthez, French
physician 1734 -1806 Urine Friedrich Woher, German chemist 1800 -
1882
Slide 36
Homework Read chapter 2.1. Use Jmol to view molecules from
todays lesson Do you have any questions about this topic? Is there
anything in this chapter you would like to investigate
further?
