Chemistry
Session
Session Objectives
1. Enzymes
2. Cofactors
3. Sucrase Mechanism
4. Carboxypeptidase
5. Metabolism
6. DNA and RNA
7. Lipids
8. Hormones and Vitamins
Enzymes
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
Cofactors
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
Types of Enzymes by Function
Enzymes are usually grouped according to the kind of reaction they catalyze, not by their structures
How Do Enzymes Work? Citrate Synthase
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
Sucrase Mechanism
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Sucrase Mechanism
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Active Site of Carboxypeptidase
Carboxypeptidase's
The Structure of Citrate Synthase
Determined by X-ray crystallography
Enzyme is very large compared to substrates, creating a complete environment for the reaction
Aspects of Metabolism
Metabolism.
The life process.
–Catabolism.
• Substances are broken down.
–Anabolism.
• Substances are built up.
Metabolism
• Lipid metabolism.
–Uptake of fats through walls of intestine.
–Glycerol converted to glyceraldehyde-3-phosphate.
–Fatty acids are oxidized by –oxidation.
• Protein metabolism.
–Stomach:
• HCl and pepsin hydrolize 10% of peptide bonds.
–Intestine:
• Trypsin and chymotrypsin cleave peptide fragments further.
Components of DNA and RNADNA: 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.
DNA Double Helix
RNA Single Strand
Focus On Protein Synthesis and the Genetic Code
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.
Transcription
How RNA polymerase, guided by base
pairing, synthesizes a single-stranded
mRNA copy of a gene’s DNA template
Protein Synthesis(Translation)
Translation
How base pairing between mRNA and tRNAs directs the assembly of a polypeptide on the ribosome
DNA Replication
Click here
Lipids
Some Common Fatty Acids
Saponification
Fats and Oils
Both are triglycerides.
–Differ in the nature of the acid components attached.
– Both are colorless, odorless and tasteless
– Flavors and aromas come from organic impurites.
Fats.
–Predominantly saturated fatty acids.
–Normally solid at room temperature
Oils.
–Predominantly unsaturated fatty acids.
–Liquids at room temperature.
Butter
“Calorie-Free” Fats
Phospholipids
Phospholipids
Hormones
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.
Adrenal cortical horm ones(corticodes)
Estrogen Progestrone
Fem ale sex hom ones Male sex horm ones(Androgens)
Sex horm ones
Stero ids
Peptide horm ones(insulin , g lucagon)
Am ino acid derivatives(thyroidal hormones)
Miscellaneous(Prostaglandins, cyokin ins)
Non-Stero ids
Hormones
Vitamins
They are essential dietary factors required by an organism in minute quantities.
They are essential for life and their absence causes deficiency diseases.
Vitamins catalyze biological reactions in very low concentration
Vitamins are designated A,B,C,D,etc. in order of their discovery. Subgroup vitamins are designated by number subscript e.g. B1,B2,B6,B12
Classification:A.Fat solubleB.Water soluble
Thank you