![NUCLEIC ACIDS
• Nucleic acids are the macromolecules present in all living cell.
• FREDRICH MIESCHER was the first person isolated the nucleic acids from
the pus cells. He called it as nuclein.
• As it has an acidic nature, hence ALTMANN called it as nucleic acids.
• The two types of nucleic acids found in living organisms are -
NUCLEIC ACIDS
DEOXYRIBONUCLEIC
ACID [DNA]
RIBONUCLEIC ACID
[RNA]](https://image.slidesharecdn.com/molecularbasisofinheritance-200828130009/85/Molecular-basis-of-inheritance-2-320.jpg)
![• DNA replication is a semi – conservative
method or approach. Occurs in S –
phase in cell cycle.
# MECHANISM OF DNA REPLICATION –
• The process of DNA replication takes
place by number of substance, enzymes
and proteins.
• SUBSTANCE: Deoxyribonucleotides.
• ENZYMES: DNA Helicase.
DNA Polymerase III, II, I.
RNA Primase.
DNA ligase.
• PROTEIN: SSB [ Single Strand Binding
protein]
DNA REPLICATION
DNA
POLYMERASE
I
KORNBERG & his
colleagues (1955).
DNA Replication,
proof reading, repair.
Role still
unknownII
III
•T. KORNBERG &
M.L GEFTER.
DNA chain
elongation.](https://image.slidesharecdn.com/molecularbasisofinheritance-200828130009/85/Molecular-basis-of-inheritance-20-320.jpg)
![EVIDENCE IN SUPPORT OF
SEMICONSERVATIVE MODE OF DNA
REPLICATION
• MESSELSON & STAHL (1958) –
• They grew E. coli on 15NH4Cl culture medium.
• 15N is the heavy isotope of nitrogen
• Both strands of DNA have 15N (15N 15N).
• These bacteria are Shifted to 14NH4Cl culture medium
• DNA extracted subjected to [Cesium Chloride (CsCl)] CsCl
density gradient centrifugations.
• Hybrid/ Intermediate type of DNA (15N 14N)
• After next generation equal amount of light DNA
• (14N 14N) and hybrid DNA (15N 14N) are formed.](https://image.slidesharecdn.com/molecularbasisofinheritance-200828130009/85/Molecular-basis-of-inheritance-23-320.jpg)
Molecular basis of inheritance
- 1. BY: DR. PRITIMA GUPTA
- 2. NUCLEIC ACIDS • Nucleic acids are the macromolecules present in all living cell. • FREDRICH MIESCHER was the first person isolated the nucleic acids from the pus cells. He called it as nuclein. • As it has an acidic nature, hence ALTMANN called it as nucleic acids. • The two types of nucleic acids found in living organisms are - NUCLEIC ACIDS DEOXYRIBONUCLEIC ACID [DNA] RIBONUCLEIC ACID [RNA]
- 3. DNA – DEOXYRIBONUCLEIC ACID • Term given by – ZACHARIS. • NIRENBERG H HARRIES – Isolation & purification of specific DNA segment from a living organism. # CHEMICAL COMPOSITION – SUGAR MOLECULE • Identified by LEVENE (1910) • Pentose sugar - Deoxyribose PHOSPHORICACID • As in phosphate group. NITROGENOUS BASE • KOSSEL demonstrated +nce pf pyrimidines & purines. • Awarded with Nobel price in 1910.
- 4. STRUCTURE OF DNA • NITROGENOUS BASE: Nitrogenous base are the nitrogen containing compounds. 1. Purines. 2. Pyrimidines. • PURINES: Purines are the double ring heterocyclic structural compounds. The two types of purines present in the DNA are Adenine (A) and Guanine (G). NITROGENOUS BASE PURINES ADENINE (A) GUANINE (G) PYRIMIDINES CYTOSINE (C) THYMINE (T)
- 5. • NUCLEOSIDES: Compounds formed by the combination of pentose sugar and Nitrogenous base is called nucleosides. They are called as DEOXYRIBONUCLEOSIDES. • Adenine + deoxyribose sugar = Deoxyadenosine. • Guanine + deoxyribose sugar = Deoxygaunosine. • Cytosine + deoxyribose sugar = • Deoxycytidine. • Thymine + deoxyribose sugar =Deoxythymidine. • NUCLEOTIDES: Compounds formed by the combination of nucleoside and a phosphate group is called nucleotides. • The four types of nucleotides present in the DNA are - 1. Deoxyadenosine monophosphate. 2. Deoxygaunosine monophosphate. 3. Deoxycytidine monophosphate. 4. Deoxythymidine monophosphate. N-GLYCOSIDIC LINKAGE PURINE/ PYRAMIDINE PENTOSE SUGAR NUCLEOSIDE NUCLEOSIDE PHOSPHATE NUCLEOTIDE
- 7. • A phosphate group is linked to 5′ -OH of a nucleoside through PHOSPHOESTER LINKAGE. Two nucleotides are linked through 3′-5′ PHOSPHODIESTER LINKAGE to form a dinucleotide.
- 8. • A polymer thus formed has at one end a free phosphate moiety at 5′ -end of ribose sugar, which is referred to as 5’-end of polynucleotide chain. Similarly, at the other end of the polymer the ribose has a free 3′ -OH group which is referred to as 3′- end of the polynucleotide chain. • Length of the DNA depends upon the number of base pairs +nt. • Lambda bacteriophage has 48502 base pairs (bp), E. Coli bears 4.6 x 106 bp. A haploid human DNA has 3.3 x 109 bp. • ERWIN CHARGAFF - QUANTITATIVELY A = T or A/T = 1. This is also k/as “BASE EQUIVALENCE RULE”. • QUALITATIVELY C = G or C/G = 1. • A + G = T + C. • A + C = G + T.
- 9. WATSON & CRICK MODEL • In 1953 that JAMES WATSON and FRANCIS CRICK, based on the X-ray diffraction data produced by MAURICE WILKINS and ROSALIND FRANKLIN, proposed a very simple but famous Double Helix model for the structure of DNA. • According to Watson and Crick model of DNA, ‘The DNA contains two polynucleotide strands coiled together in helical manner’. Hence the name Watson and Crick double helix structure of DNA is given. # FORMS OF DNA – • A, B, C, D and Z DNA. • Among these A, B, C, D are = Right handed helices. • Watson & Crick model represent the Biotic form of DNA – B DNA. # DIFFERENCE IN DNA FORMS – 1. No. of base pairs/turn of helix. 2. The pitch or angle b/w each base pair. 3. Handedness of the double helix. CHARACTER A - DNA B – DNA C – DNA D - DNA Z - DNA BP/TURN 11 10 9.33 8 12 TILT OF BP 20.20 6.30 -7.80 -16.70 70 HELICAL DIAMETER 23 A0 19A0 19A0 - 18A0 HANDEDNESS Right Right Right Right Left
- 10. • The two strands of DNA have the common diameter of 20 0A. • Adenine of one strand pairs with Thymine of another strand by two hydrogen bonds and vice versa. • Guanine of one strand pairs with Cytosine of another strand by three hydrogen bonds and vice versa. • Each twist of DNA contains 10 base pair. • The distance between these two base pairs are 3.4 0A. DNA PROMISCUOUS DNA which makes movement b/w mitochondria, chloroplast & nucleus REPETITIVE Multiple copies of DNA having same or almost same BP sequence. Small eukaryotes. Small highly repetitive DNA sequences have been found. SATELLITE
- 12. • One way flow of genetic information from DNA to protein is called central dogma. • DNA→ RNA→ Protein # PACKAGING OF DNA IN PROKARYOTES • Prokaryotes do not have definite nucleus. • The DNA is not scattered throughout the cell. • It is held together with some proteins in a region is called NUCLEOID • The DNA in nucleoid is organized in large loops held be proteins CENTRAL DOGMA & PACKAGING
- 13. • WOODCOCK (1973) has shown that chromatin consists of a repeating pattern of bodies k/as NUCLEOSOMES • HISTONE PROTEINS + DNA = NUCLEOSOME • Histones are positively charged due to rich in basic amino acids residues of Lysine and arginine. • Types of Histone proteins – H2A, H2B, H3 and H4. 1 histone protein has 2 molecules, so 4 histone proteins forms an octamer. An octamer is aka nu(v8) body. • The nucleosomes are seen as ‘beads-on- string’ structure under electron microscope. • Nucleosome forms the repeating unit of a NUCLEOSOMES
- 14. NUCLEAR CHROMATIN W. FLEMMING (1879) NUCLEAR RETICULUM HETEROCHROMATIN Permanently inactive – CONSTITUTIVE Temporary inactive - FACULTATIVE EUCHROMATIN TRUE CHROMATIN Transcriptionally active
- 15. # TRANSFORMING PRINCIPLE/ BACTERIAL TRANSFORMATION/ GRIFFITH EFFECT – • In 1928, FREDERICK GRIFFITH, conducted experiments to show transforming principle in bacteria. • He conducted an experiment on mice and pneumonia bacteria streptococcus pneumoniae. • These bacteria are found in two strains, as • 1 virulent (smooth strain) S Strain • 2 non-virulent (rough strain) R Strain • The S-strain bacteria produce capsule and is pathogenic. • The R-strain lacks capsule and is non pathogenic. THE SEARCH FOR GENETIC MATERIAL
- 16. • When the R-strains are injected into the mouse, it is a non pathogenic and does not causes pneumonia. The mouse continued to live. • When the S-strains are injected into the mouse, that causes pneumonia and mouse dies. • When heat killed S-strains are injected into the mouse that does not causes pneumonia. The mouse continued to live. • When the heat killed S-strains and R-strain are mixed and injected into the mouse, that causes pneumonia and mouse dies. # CONCLUSION OF EXPERIMENT: • R – Strain bacteria had been transformed by the heat killed S-Strain bacteria. • The transformation of R-Strain to S-Strain is due to transfer of Genetic material. • The biochemical nature of genetic material was not defined from his experiment.
- 17. BIOCHEMICAL CHARACTERIZATION OF TRANSFORMING PRINCIPLE • OSWALD AVERY, COLIN MACLEOD & MACLYN MC CARTY. (1933-44) worked to determine the biochemical nature of the ‘transforming principle’ of Griffith’s experiment. • Heat killed S-Strain + protease + Live R- Strain → transforms R strain to S strain. • Heat killed S-Strain + RNase + Live R- Strain → transforms R strain to S strain. • Heat killed S-Strain + DNase + Live R- Strain → unable to transforms R strain to S strain • # CONCLUSION OF THE EXPERIMENT – • Protein of heat killed S-Strain is not the genetic material • RNA of heat killed S-Strain is not the genetic material. • DNA of heat killed S-Strain is the genetic material. • – Because DNA digested with DNase mixed with R-strain unable to transform R-Strain to S-Strain.
- 18. • ‘DNA is the genetic material’ is proved by ALFRED HERSHEY and MARTHA CHASE (1952). • They worked on the virus that infects bacteria called bacteriophage. • During infection the bacteriophage first attaches the bacteria cell wall. It inserts its genetic material into the bacterial cell. • Viruses (T2 bacteriophage) were grown in one of two isotopic mediums in order to radioactively label a specific viral component Viruses grown in radioactive sulphur (35S) had radiolabelled proteins (sulphur is present in proteins but not DNA) • Viruses grown in radioactive phosphorus (32P) had radiolabelled DNA (phosphorus is present in DNA but not proteins BACTERIOPHAGE INFECTION (TRANSDUCTION)
- 19. 1. REPLICATION - It should be able to generate its replica. 2. STABILITY - It should be chemically and structurally stable. 3. MUTATION - It should provide slow changes (mutation) that required for evolution. 4. GENETIC EXPRESSION - It should be able to express itself in the form of ‘Mendelian Character’. REQUIRED PROPERTIES OF GENETIC MATERIAL DIFFERENCE B/W DNA & RNA
- 20. • DNA replication is a semi – conservative method or approach. Occurs in S – phase in cell cycle. # MECHANISM OF DNA REPLICATION – • The process of DNA replication takes place by number of substance, enzymes and proteins. • SUBSTANCE: Deoxyribonucleotides. • ENZYMES: DNA Helicase. DNA Polymerase III, II, I. RNA Primase. DNA ligase. • PROTEIN: SSB [ Single Strand Binding protein] DNA REPLICATION DNA POLYMERASE I KORNBERG & his colleagues (1955). DNA Replication, proof reading, repair. Role still unknownII III •T. KORNBERG & M.L GEFTER. DNA chain elongation.
- 21. 1. RECOGNITION OF THE INITIATION POINT Unwind helix with the help of HELICASE ENZYME by breaking H bonds. It creates a REPLICATION FORK & ORIGIN OF REPLICATION (ORI). 2. UNWINDING OF DNA TOPOISOMERASE catalyze and guide the unknotting or unlinking of DNA by creating transient breaks in the DNA. 3. SINGLE STRANDED BINDING PROTEIN (SSB) – Stabilizes DNA. 4. RNA PRIMING – The DNA dependent RNA polymerase synthesizes RNA Primer. Acts as a starting point. It works complementary to the template DNA strand. It comprises of 50 – 100 nucleotides. 5. FORMATION OF DNA ON RNA PRIMER – Done by DNA polymerase in . 5' to 3' direction. Addition of DNA to 3’ end of primer RNA. It is done by DNA Polymerase III. LEADING STRAND – 5’ → 3’ CONTINUOUS STRAND. LAGGING STRAND – 3’ → 5’ DISCONTINUOUS STRAND. Lagging strand creates OKAZAKI FRAGEMENTS i.e. small fragments. These fragments are joined by DNA LIGASE.
- 22. 6. EXCISION OF RNA PRIMERS RNA primer are removed from 5’ end with the help of exonuclease DNA polymerase I. 7. JOINING OF OKAZAKI FRAGMENTS – Gaps between okazaki fragments are filled with DNA residues by DNA Polymerase I. done with DNA ligase.
- 23. EVIDENCE IN SUPPORT OF SEMICONSERVATIVE MODE OF DNA REPLICATION • MESSELSON & STAHL (1958) – • They grew E. coli on 15NH4Cl culture medium. • 15N is the heavy isotope of nitrogen • Both strands of DNA have 15N (15N 15N). • These bacteria are Shifted to 14NH4Cl culture medium • DNA extracted subjected to [Cesium Chloride (CsCl)] CsCl density gradient centrifugations. • Hybrid/ Intermediate type of DNA (15N 14N) • After next generation equal amount of light DNA • (14N 14N) and hybrid DNA (15N 14N) are formed.
- 24. • S. OCHOA Nobel prize for artificial synthesis of RNA. # STRUCTURE OF RNA • Mostly RNA are single stranded. • Sugar – Ribose • Phosphate – H3PO4. • Nitrogenous base pair – PURINE – A & G PYRAMIDINE – U & C RIBONUCLEIC ACID (RNA) TYPES OF RNA GENETIC RNA CONRAT established. RNA acts as a genetic material. NON – GENETIC RNA Do not act as a genetic material. They are of 3 types – mRNA, tRNA & rRNA
- 25. # MESSENGER RNA (mRNA) • Carries genetic info in cytoplasm for protein synthesis. • JACOB and MONOD 1961) named mRNA. • Template strand for protein synthesis. • Short life span. • Total RNA 5%. # RIBOSOMAL RNA (rRNA) • In eukaryotes, ribosomes – rRNA occurs as particles of 4 d/f dimensions – 28S, 18S, 5.8S & 5S. • Large subunit = 60S • Small subunit = 40S • Total RNA 80%. # TRANSFER RNA (tRNA) • Comprises of 60 small sized RNA. • Recognises the codons of mRNA & carries them to the site of protein synthesis. • Also k/as SOLUBLE RNA or ADAPTER RNA or SUPERNATANT RNA. • Smallest • 2 sites – 3’ Amino acid group attached (activated) Anticodon loop • Most accepted model of tRNA = CLOVER LEAF MODEL. ROBERT HOLLEY (1965) + H. G. KHORANA & NIRENBERG received Nobel prize (1968).
- 26. • Sites on tRNA 1. Amino acid attachment site – 3’ end. 2. Site for activating enzyme – dehydovidine or DH4 loop dictate activation of enzyme. 3. Anticodon or codon recognition site: 3 unpaired bases. 4. Ribosome recognition site – tRNA gets attached to ribosome # OTHER TYPES OF RNA 1. snRNA Small Nuclear RNA. It helps in splicing, RNA processing and mRNA processing HnRNA Heterogenous nuclear RNA. It is a larger molecule. It is an mRNA precursor scRNA Small conditional RNA. Small sized RNA. Helps in taking and binding ribosome + ER.
- 27. • Formation of RNA from DNA template. # TRANSCRIPTION UNIT – 1. Promoter 2. Structural gene 3. Terminator • Parental DNA – Template strand 3’→5’ • Coding strand – 5’→3’ ( It codes for nothing ) • Promoter is situated towards the 5’ end of coding strand i.e., at 3’ end of template strand ahead of structural gene. • Structural gene is the gene which is to be transcripted and is +nt on template strand. • Terminator is situated towards the 3’ end of coding strand i.e. at 5’ end of template strand behind structural gene. TRANSCRIPTION
- 28. TRANSCRIPTION PROCESS INITIATION RNA polymerase + σ sigma, initiation factor. The unwinding of DNA continues till desired length through RNA polymerase II ELONGATION TERMINATION RNA polymerase + rho, terminator factor INEUKARYOTES RNA POLYMERASE I Transcribes rRNAs 28S, 18S & 5.8S RNA POLYMERASE II Transcribes HnRNA (mRNA precursor) RNA POLYMERASE III Transcribes tRNA, 5srRNA, SnRNA Normally, mRNA carries the codons of single complete protein – MONO – CISTRONIC mRNA; several cistrons – POLY CISTRONIC # SPLICING – DNA comprises of exons and introns Removal of introns – SPLICING. HnRNA – capping (5’) Methyl guanosine triphosphate + tailing (3’) Adenylate residues
- 29. The mRNA molecule after tailing and caping moves to cytoplasm as free nucleoprotein complex k/as INFORMOSOME.
- 30. • It is basically that structure of nitrogenous base in mRNA which possess protein formation information. • CRICK discovered it by frame shift mutation. • CODON Codes for specific amino acid • NIRENBERG & MATHAEI (1961) Determined that 3 nitrogenous base together are k/as triplet codon & they code for 1 amino acid. • Genetic code noble prize – KHORANA # SALIENT FEATURES OF GENETIC CODE 1. Triplet codon 2. Comma less 3. Universal 4. Non – overlapping nucleotides 5. AUG – acts as Initiation codon & codes for methionine. 6. UAA (Ochre), UGA (Opal) or UAG (Amber)– Termination codon WOBBLE POSITION/ HYPOTHESIS First 2 bases of tRNA anticodon specifically undergo for hydrogen bonding. However, third base can form unusual base pairing. Because, it can Wobble, position is called WOBBLE POSITION. GENETIC CODE
- 32. • Change of single base pair in the gene – POINT MUTATION. Example: Sickle cell anemia. • RAM HAS RED CAP • RAM HAS BRE DCA P • RAM HAS BIR EDC AP • RAM HAS BIG RED CAP • The same can be repeated, by deleting the letters R, E and D, one by one and rearranging the statement to make a triplet word. • RAM HAS EDC AP • RAM HAS DCA P • RAM HAS CAP • The smallest part of gene that can mutate – MUTON. • TAUTOMERISM – Pairing of purine with purine and pyrimidine with pyrimidine. • SUBSTITUTIONS/ REPLACEMENTS – These are gene mutations where one or more nitrogenous base pairs are changed with others. They are of 3 types – 1. TRANSITION – when in a triplet codon purine replaces purine & pyrimidine replaces pyrimidine. 2. TRANSVERSION – purine is replaced by pyrimidine or vise a versa. 3. FRAME SHIFT/ INSERTION/ DELETION – addition/ deletion of single base takes place. None of the codon remains in the same original position. • Gene mutations that involve the substitution, deletion or insertions of more than one base pair or entire genes – GROSS MUTATIONS. MUTATIONS AND GENETIC CODE
- 33. • Process of formation of protein with the help of amino acid chain. • During transcription mRNA is being formed in the nucleus which later enters cytoplasm. • In cytoplasm, mRNA attaches itself with small ribosomal unit. • A molecular mechanism by which a gene expresses a phenotype by synthesizing a protein or an enzyme, which determines the character is k/as GENE EXPRESSION • It is a process by which information stored in the DNA in the form of genes is used in the synthesis of functional gene products. TRANSLATION Ribosome Large subunit (60s) Small subunit (40s)
- 34. • A recognition enzyme attaches itself with large ribosomal unit. • This complex formed now searches for start codon (AUG) on mRNA & once found this complex gets attached at that site. • The P site attaches itself at mRNA such that tRNA adapter molecule attaches with the start codon site. • mRNA is read by the P site and adapter molecule with requires amino acid. • The amino acid joins and forms a chain where as the adapter molecule exit through the E site. • The process stops when a stop codon is encountered where a release factor binds. • The shift of ribosomes along mRNA is called TRANSLOCATION. 60s EXIT (E) PROMOTER/ DONOR/ PEPTIDYL (P) AMINO-ACYL /ACCEPTOR (A)
- 36. • U.S. govt. started Human genome project in 1990 coordinated by the Department of Energy and the National Institutes of Health. • GENOME – The whole hereditary information of an organism that is encoded in the DNA is called genome. • Human Genome Project (HGP) was called a MEGA PROJECT because - 1. Human genome have approximately 3 x 109 bp. The cost of sequencing required 3 US $ per bp. Then total estimated cost of the project is 9 billion US dollars. 2. The obtained sequences were to be stored in typed form in books. If each page of the book contained 1000 letters. each book contained 1000 pages. Then 3300 such books need to store information from a single human cell. HUMAN GENOME PROJECT
- 37. AIMS OR GOALS OF HUMAN GENOME PROJECT 1. Identify all the approximately 20,000- 25,000 genes in human DNA; 2. Determine the sequences of the 3 billion chemical base pairs that make up human DNA; 3. Store this information in databases; 4. Improve tools for data analysis; 5. Transfer related technologies to other sectors, such as industries; 6. Address the ethical, legal, and social issues (ELSI) that may arise from the project. # METHODOLOGIES– 1. Identifying all the genes that expressed as RNA (Expressed Sequence Tags - ESTs). 2. Blind approach of simply sequencing the whole set of genome. That contained all the coding and noncoding sequence. later assigning different regions in the sequence with functions (Sequence Annotation
- 38. # SALIENT FEATURES OF HUMAN GENOME PROJECT – 1. The human genome contains 3164.7 million nucleotide bases. 2. The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases. 3. The total number of genes is estimated at 30,000– much lower than previous estimates of 80,000 to 1,40,000 genes. Almost all (99.9 per cent) nucleotide bases are exactly the same in all people. 4. The functions are unknown for over 50 per cent of discovered genes. 5. Less than 2 per cent of the genome codes for proteins. 6. Repeated sequences make up very large portion of the human genome. 7. Repetitive sequences are stretches of DNA sequences that are repeated many times, sometimes hundred to thousand times. They are thought to have no direct coding functions, but they shed light on chromosome structure, dynamics and evolution. 8. Chromosome 1 has most genes (2968), and the Y has the fewest (231). 9. Scientists have identified about 1.4 million locations where single- base DNA differences (SNPs – single nucleotide polymorphism, pronounced as ‘snips’) occur
- 39. • Gene regulation is the ability of a cell to control or regulate what proteins it makes from its DNA. • French scientist JACOB & MONOD (1961) - OPERON – Segment of DNA i.e. genetic material which function as regulated unit that can be switched on and off. • Experimentally they demonstrated the regulation of gene in E.coli. • The sequential arrangement of regulatory gene, promoter gene, operator gene and structural genes in prokaryotes is called operon concept. • REGULATORY SEQUENCE – few 100s to 1000s base pair long. Behind main protein coding genes. It is site of attachment fro enzyme RNA polymerase. • REGULATORY GENES lie few 1000s base pairs away/ behind the protein coding genes. They synthesizes a protein c/as REGULATORY PROTEIN This protein goes and control binding of RNA polymerase to regulatory sequence. • Regulatory sequence – regions – PROMOTER(P); OPERATOR(O); REPRESSOR(I). LAC OPERON/ INDUCIBLE LAC OPERON
- 40. • Structural gene – genes producing mRNA. • Z = produces β galactosidase – breaks lactose into galactose and glucose. • Y = produces galactoside permease – increases permeability for β galactosidase. • A = produces enzyme transacetylase – function not known yet.
- 41. • Given by ALEC JEFFERY in 1985 • DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called as repetitive DNA. • These repetitive DNA are separated from bulk genomic DNA at different peaks during density gradient centrifugation. The bulk DNA forms a major peak and the other small peaks are referred to as satellite DNA. • These sequences show high degree of polymorphism and form basis of DNA fingerprinting. • The principle of DNA finger printing is based on matching of VNTRs of DNA collected at crime spot with suspect person DNA. • VNTRs VARIABLE NUMBER OF TANDEM REPEATS It is also called as mini satellites that shows very high degree of polymorphism. • VNTRs are very specific to individual and differs from person to person. • SOUTHERN BLOTTING It is the technique of transferring DNA from agar gel to nylon sheath. • PROBE Single stranded polynucleotide fragment complementary to specific sequence of nucleotides of • DNA is called probe. It is mainly used in identify VNTRs and desired gene DNA FINGERPRINTING
- 42. # METHOD OF DNA FINGERPRINTING – 1. Isolation of DNA. 2. Digestion of DNA by restriction endonucleases. 3. Separation of DNA fragments by electrophoresis. 4. Transferring (SOUTHERN BLOTTING) of separated DNA fragments to nylon sheath. 5. Hhybridization using labelled VNTR probe,. 6. Detection of hybridized DNA fragments by autoradiography.
- 43. APPLICATION OF DNA FINGER PRINTING TECHNOLOGY 1. It is used to identify criminals and rapist. 2. To solve parental dispute. 3. To solve immigrant problems. 4. To identify dead bodies of soldiers died in wars. 5. To identify dead bodies of person died at accidents and bomb blast. 6. To identify racial groups. 7. To detect inheritable disorders. 8. To detect donor cell in case of transplantation.