1.3 the chemistry of life

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how does each cell have a highly complex chemical system

1. based largely on carbon compounds

2. dependent on chemical reactions that take place in aqueous environments in a narrow temperature range

3. enormously varied in its chemistry

4. dominated and coordinated by biomacromolecules

5. tightly regulated such that each chemical reaction occurs at the proper rate, time, place

what are the molecular compositions of a cell

1. lipids

2. nucleic acids

3. proteins

4. carbohydrates

what is the sub unit of lipids (polymer)

fatty acid, glycerol (monomers)

what is the sub unit of nucleic acid

nucleotides

what is the sub unit of proteins

amino acids

what is the sub unit of carbohydrates

simple sugars

what is the reaction called when H₂O is produced and thus the polymer is formed

condensation / dehydration

what is the reaction when H₂O is used and thus the polymer broken down

hydrolysis

what is the role of carbohydrates

• plays important energy storage and structural roles in the cell

• carbohydrates include sugars and polymers of sugars

what are the types of sugars

• simplest: monosaccharides / single sugars (eg glucose)

• macromolecules: polysaccharides / composed of multiple sugar units

• characterised by a general molecular formula of C_n(H₂O)_n-1

what is the covalent bond formed for carbohydrates

glycosidic bond

what is the role of lipids (fats, phospholipids, steroids)

• plays role in insulation, energy storage, cell structure and cell signaling

• a class of large molecules comprising mostly of hydrocarbons (C, H)

  • non-polar in nature → insoluble with little affinity for water

• do not form long, repeating polymers

what is the reaction to form lipids

• linked together by dehydration

• triglycerides are constructed from 2 types of smaller molecules → glycerol and fatty acids

  • glycerol is a 3 carbon alcohol with a hydroxyl group on each carbon

  • a fatty acid consists of a carboxyl group attached to a long carbon tail

what is the bond for lipids

ester bond

what is the role of proteins

• play a diverse and important range of cellular functions, including structural support, transport, communication etc

• biologically functional molecule that consists of one of more polypeptide chains

• a polypeptide is a linear polymer built from a set of 20 amino acids linked by covalent peptide bonds

what is the reaction to form proteins

• dehydration reaction

• 2 amino acids undergo a dehydration reaction to yield a dipeptide linked by a covalent peptide bond

what is the bond between proteins

peptide bond

what is the role of nucleic acids

• storage, transmission and use of genetic information

• nucleic acids are also called polynucleotides

  • polynucleotides are made of subunits called nucleotides linked together by covalent phosphodiester bonds

what is the reaction to form nucleic acids

• condensation reaction

  • between the hydroxyl group on the sugar of one of the nucleotide and the phosphate group of the next nucleotide to form a phosphodiester bond

what is the bond between proteins

phosphodiester