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GeneticsGenetics

Mr.Yogesh V. UshirPharmaceutical Biochemistry

Metabolism & biosynthesis of Nucleotides

Purine synthesis

Purine catabolism

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Uric acid metabolism

Gout

Hyperuricemia

Xanthinuria (deficiency of the enzyme ‘xanthine oxidase’)

Von Gierke’s disease

Lesch-Nyhan syndrome

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Biosynthesis of Nucleic acid

Nucleic acid formed by polymerization of several nucleotides

DNA guide its own synthesis but RNA cannot, it is guided by DNA

The synthesis of additional DNA is known as ‘replication’ & it done by DNA- polymerase

The synthesis of RNA is known as ‘transcription’ & it is done by RNA-polymerase

For each gene in the DNA molecule, there is a ‘sense’ strand & its complementary ‘antisense’ strand

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Genetic & Nucleic acid Chromatin: chromosomal material extracted from cell

nuclei of eukaryotic cells is called chromatin. It contains equal amounts of DNA & proteins. The proteins are mainly histones (basic) & small

amount of acidic non-histone proteins

Chromosome: One of the threadlike "packages" of genes and other DNA in the nucleus of a cell.

Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes.

Gene: The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

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Chromosome

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GENEGENE

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Protein SynthesisProtein Synthesis Site of synthesis - the bulk of protein synthesis takes

place in the ribosomes of the endoplasmic reticulum

m-RNA - an ultimately a genes, which are DNA molecules in the chromosomes, that determine the type of protein to be synthesized by the cell.

For every protein there is specific gene guiding the process

The replication of a messenger RNA from the DNA of the gene is described as ‘Transcription’ & is mediated by the enzyme ‘RNA polymerase II’

The portion of DNA strand which is concerned with the synthesis of any single polypepeide chain is called a ’Cistron’.

Polyribosomes- the m-RNA so formed in nucleus migrates into the cytoplasm & attaches itself to a number of ribosomes. This complex structure is Polyribosome.

The genetic code in protein synthesis

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in case of DNA, the 4 bases A,G,T & C can form 64 different base combinations (triplet) – AAA, AAG, AAT, AAC, AGA, ACA, & so on

Each triplet represents the code word for an amino acid.

There are may be more than one triplet for amino acid

The m-RNA carries the code.

Each triplet called ‘CODON’

Mutation

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Mutation can be occur when there is alteration in the bases of DNA of genes

UV rays, acridine dyes & alkylating agents cause mutations by theire varying effects on the bases

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