2.1: Molecules to metabolism

Which elements are the most commonly occurring in living organisms?

Research: uses of these elements, in plants/animals or both…  Hydrogen ions  Oxygen  Nitrogen  Iron  Calcium  Phosphorous  Sulphur  Sodium & Potassium

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)

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)

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

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

CategorySub-categoryExamples CarbohydratemonosaccharideGlucose, galactose, fructose disaccharideMaltose, lactose, sucrose polysaccharideStarch, glycogen, cellulose ProteinsEnzymes, antibodies LipidsTriglycerides, phospholipids Nucleic acidsDNA, RNA

Example Qu.

What am I? 1. I don’t 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.

Molecular Drawings! You need to be able to draw and recognize: Glucose Ribose A saturated fatty acid Generalized amino acid Pages 65/66

What is this? Amino acid!

Mono, Di or Poly? Maltose Disaccharide

What is this? Saturated fatty acid

Mono, Di or Poly? Glycogen Polysaccharide

What is this? Ribose

What is this? Unsaturated fatty acid

Mono, Di or Poly? Fructose Monosaccharide

Glucose What is this?

How are you going to remember these structures?

Can you SPOT the difference?

What are these? Phospholipid Triglyceride Steroid

Important groups to remember Hydroxyl group Amine group Methyl group Carboxyl group

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.

The connection of small molecules to form larger molecules releasing water. + Water Condensation reactions

Example of a condensation reaction. Peptide bond

Example Qu. Answer: III

Hydrolysis Addition of water, breaking bonds between molecules + Water

Example… Glycosidic bond

Example Qu.

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)

What do these have in common? Paul Joseph Barthez, French physician Urine Friedrich Woher, German chemist

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?