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MOLECULAR BASIS OF INHERITANCE

MOLECULAR BASIS OF INHERITANCE. PREPARED BY MRS. S RATH PGT BIOLOGY. www.cbse123.co.cc. DNA (Polynucleotide). DNA. Nitrogenous base is linked to pentose sugar through a n-glycosidic linkage to form a nucleoside.

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MOLECULAR BASIS OF INHERITANCE

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  1. MOLECULAR BASIS OF INHERITANCE PREPARED BY MRS. S RATH PGT BIOLOGY www.cbse123.co.cc

  2. DNA (Polynucleotide)

  3. DNA • Nitrogenous base is linked to pentose sugar through a n-glycosidic linkage to form a nucleoside. • Phosphate group attached to5’-OH of a nucleoside through phospho-ester linkage, and a nucleotide is formed. • Two nucleotides are linked through 3’-5’ phosphodiester linkage to form a dinucleotide, and in this manner many nucleotides are linked forming polynucleotide. • A polynucleotide has a free sugar at its5’ end and a free phosphate at its 3’ end.

  4. Double helix model of DNA( Watson and Crick model) • DNA is made of 2 polynucleotides. • Backbone is formed by sugar and phosphate. • Nitrogen bases project inside. • Hydrogen bonds between nitrogen bases hold the chain together. • Adenine pairs with thymine through 2 hydrogen bonds and guanine with cytosine with 3 bonds. • Two chains have antiparallel polarity. • Two chains are coiled in a right handed fashion. And pitch of each helix is3.4nm, and 10 base pairs in each turn.

  5. A NUCLEOSOME

  6. Griffith’s experiment on transformation

  7. DNA is the genetic material

  8. Characteristics of genetic material • Able to generate its replica. • Chemically and structurally stable. • Provide the scope for mutation necessary for evolution. • Able to express itself in the form of Mendalian character.

  9. RNA (Polynucleotide)

  10. TYPES OF RNA

  11. A tRNA MOLECULE

  12. Semiconservative replication of DNA

  13. Meselson- Stahl experiment(semiconservative replication)

  14. Replication of DNA(schematic representation)

  15. A TRANSCRIPTION UNIT • A promoter • Structural genes • A terminator

  16. A TRANSCRIPTION UNIT Transcription

  17. TRANSCRIPTION IN PROKARYOTES

  18. GENETIC CODE • Codons are triplets • 61 codons code for 20 amino acids. • Unambigous – each coden codes for only one/ particular amino acid. • Degenerate – some amino acids are coded by more than one codon. • Commaless –codons are read in continuous manner in a 5’ to 3’ direction without punctuation • Universal –codes for same amino acid in any organism. • AUG- initiation codon and codes for methionine. • UAA, UAG and UGA are stop codons..

  19. MUTATION

  20. TRANSLATION

  21. TRANSLATION

  22. TRANSLATION

  23. COMPONENTS OF OPERON • Structural gene • Promoter gene • Operator • Regulator gene • Inducer

  24. LAC OPERON IN E.COLI

  25. LAC OPERON IN E.COLI

  26. GOALS OF HUMAN GENOME PROJECT (HGP) • Identification of all genes • Determination of the sequence of the 3 billion base pairs in human DNA. • To store the information in data base. • Improvement of the tools for data analysis • Transfer of the technology to other sectors (industries) • To address the ethical, legal and social issues (ELSI) that may arise from this project.

  27. METHODOLOGIES OF HGP • Expressed sequence tags (ESTs)- identifying all genes that expressed as RNA. • Sequence annotation- sequence the whole sequence of genome, that included all coding and noncoding sequences and later assigning function to different regions in the sequence.

  28. SALIENT FEATURES OF HUMAN GENOME • Contains3164.7 million nucleotides. • Size of genes varies, average size contains 3000 bases, the largest gene dystrophin contains 2.4 million bases. • Total no. genes about 30000 and99.9 % of the nucleotides are same in all humans. • Function of 50% genes are not known. • 2% of the genome codes for protein. • Repetitive sequence make up large portion of genome which throw light on structure, dynamics and evolution though they do not have coding function. • In 1.4 million locations DNA differs in single base.

  29. USES OF HGP • To diagnose, treat and prevent a number of disease or disorder that affects human beings. • Provides clues to the understanding of human biology.

  30. THE PROCESS OF DNA FINGER PRINTING

  31. STEPS OF DNA FINGERPRINTING • Extraction • Amplification • Restriction digestion • Separation of DNA sequence/ restriction fragments • Southern blotting • Hybridisation • Autoradiography

  32. USES OF DNA FINGERPRINTING • To identify criminals • To determine the true biological mother or father in case of disputes • To verify an immigrant, really a close relative of a resident • To identify racial groups to rewrite the biological evolution.

  33. WWW.CBSE123.CO.CC "I find that the harder I work, the more luck I seem to have."- Thomas Jefferson

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