Chemistry. Session. BIOMOLECULES - 2. Session Objectives. Enzymes Cofactors Sucrase Mechanism Carboxypeptidase Metabolism DNA and RNA Lipids Hormones and Vitamins. Enzymes. An enzyme is a protein that acts as a catalyst for a biological reaction.
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BIOMOLECULES - 2
An enzyme is a protein that acts as a catalyst for a biological reaction.
Most enzymes are specific for substrates while enzymes involved in digestion such as papain attack many substrates
In addition to the protein part, many enzymes also have a nonprotein part called a cofactor
The protein part in such an enzyme is called an apoenzyme, and the combination of apoenzyme plus cofactor is called a holoenzyme. Only holoenzymes have biological activity; neither cofactor nor apoenzyme can catalyze reactions by themselves
A cofactor can be either an inorganic ion or an organic molecule, called a coenzyme
Many coenzymes are derived from vitamins, organic molecules that are dietary requirements for metabolism and/or growth
Enzymes are usually grouped according to the kind of reaction they catalyze, not by their structures
Citrate synthase catalyzes a mixed Claisen condensation of acetyl CoA and oxaloacetate to give citrate
Normally Claisen condensation require a strong base in an alcohol solvent but citrate synthetase operates in neutral solution
Determined by X-ray crystallography
Enzyme is very large compared to substrates, creating a complete environment for the reaction
DNA: Deoxyribonucleic acid.
Chromosomes: Double stranded DNA rod-like structures.
Genes: Specific locations on chromasomes that code for specific traits.
RNA: Ribonucleic acid
Contains ribose instead of deoxyribose.
Generally single stranded.
The genetic code
How triplets of the four nucleotides unambiguously specify 20 amino acids, making it possible to translate information from a nucleotide chain to a sequence of amino acids.
How RNA polymerase, guided by base pairing, synthesizes a single-stranded mRNA copy of a gene’s DNA template
How base pairing between mRNA and tRNAs directs the assembly of a polypeptide on the ribosome
Hormones are molecules that transfer information from one group of cells to a distant tissue or organ.
They are produced by various endocrine glands.
They are classified on the basis of their structure or site of activity in the cell.