GENETIC DISORDERS & STRUCTURE OF DNA,

GENETIC DISORDERS& STRUCTURE OF DNA,BY:-HIMANSHU LATAWABIOLOGY LECTURERG.G.S.S.SCHOOLSIRHIND MANDIanshu223@gmail.com9815543311Punjab EDUSAT Society {PES}

GENETIC DISORDERSTYPES: MENDELIAN DISORDERS & CHROMOSOMALDISORDERSMENDELIAN DISORDERS:GENETIC DISORDER DUE TO GENE MUTATIONS.HAEMOPHILIA: DEFECT OF BLOOD WHICH PREVENTSITS CLOTTING.SEX-LINKED TRAIT CAUSED BY RECESSIVE GENE ‘h’ ONX CHROMOSOME.THIS GENE CONTROLS SYNTHESISOF PROTEIN NEEDED FOR CLOTTING OF BLOOD.Punjab EDUSAT Society {PES}

INHERITANCEPunjab EDUSAT Society {PES}

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• COLOUR BLINDNESS: SEX LINKED TRAIT.• CAUSED BY X-LINKED RECESSIVE GENE BY CAUSING LACK OF CONEPIGMENTS OF RETINA.Punjab EDUSAT Society {PES}

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SICKLE CELL ANAEMIA• AUTOSOMAL HEREDITARY DISEASE.• CHARACTERISIZED BY SICKLE SHAPED REDBLOOD CORPUSCLES• DEFECT CAUSED BY SUBSTITUTION OF GLUTAMICACID BY VALINE OF BETA GLOBIN CHAIN OFHAEMOGLOBIN MOLECULE• MUTANT HAEMBOGLOBIN UNDERGOESPOLYMERISATION CAUSING CHANGE IN SHAPE OFRBC’SPunjab EDUSAT Society {PES}

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Normal RBCsAnemic RBCs(Sickle cell)Punjab EDUSAT Society {PES}

• SICKLE CELL TRAIT: PERSON MAY HAVE ONE GENE FOR NORMALHAEMOGLOBIN & ONE GENE FOR SICKLE CELL HAEMOGLOBIN[Hb A ,Hb S ] THIS HETEROZYGOUS CONDITION IS SICKLE CELL TRAITPunjab EDUSAT Society {PES}

PHENYLKETONURIA• INBORN ERROR OF METABOLISM ALSO INHERITED ASAUTOSOMAL RECESSIVE TRAIT.• CHARACTERISED BY ABNORMAL INCREASE IN LEVELOF PHENYLALANINE IN BLOOD DUE TO ABSENCE OFENZYME PHENYLALANINE HYDROXYLASE.• PHENYLALANINE DOESN’T CHANGE INTO TYROSINE,GETS ACCUMULATED• RESULTS IN SEVERE MENTAL RETARDATIONPunjab EDUSAT Society {PES}

CHROMOSOMAL DISORDERS• CAUSED DUE TO ABSENCE OR EXCESSOR ABNORMAL ARRANGEMENT OF ONEOR MORE CHROMOSOMES.• ANEUPLOIDY: FAILUREOF SEGREGATION OF CHROMATIDSDURING CELL DIVISION RESULTS INGAIN OR LOSS OF A CHROMOSOME.Punjab EDUSAT Society {PES}

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• DOWN’S SYNDROME:AN ANEUPLOIDTRISOMIC DISEASE.• BOTHCHROMOSOMES NO.21 PASS INTOSINGLE EGG DUE TONONDISJUNCTIONDURING OOGENESISIN OVARY• EGG HAS 24CHROMOSOMES &OFFSPRING HAS 47CHROMOSOMESPunjab EDUSAT Society {PES}

TRISOMY -21Punjab EDUSAT Society {PES}

• ALSO KNOWN AS 21- TRISOMY.• CHARACTERISED BY ROUNDED FACE ,BROAD FOREHEAD ,PERMANENT OPEN MOUTH,PRITUDING TONGUE,FLATHANDS.• VICTIM HAS LITTLE INTELLIGENCEPunjab EDUSAT Society {PES}

• KLINEFELTER’S SYNDROME:• ANEUPLOID CONDITION WITH 3 SEX CHROMOSOMES.Punjab EDUSAT Society {PES}

• CAUSED BY UNION OF NONDISJUNCTXX EGG & NORMAL Y CHM.OR NORMALX EGG & ABNORMAL XY SPERM.• PERSON IS STERILE MALE WITHUNUSUALLY LONG LEGS, SPARSEBODY HAIR & MANY FEMALECHARACTERISTICSPunjab EDUSAT Society {PES}

• TURNER’S SYNDROME: AN ANEUPLOIDCONDITION WITH A SINGLE SEX CHROMOSOME.• PRODUCED BY FUSION OF AN ABNORMAL O EGG WITH X SPERMOR A NORMAL X EGG & ABNORMAL O SPERM• HAS 45 CHROMOSOMES.• INDIVIDUAL IS STERILE FEMALE WITH UNDERDEVELOPEDBREASTS,REDUCED OVARIES SHORT STATURE & MANY MALECHARACTERISTICS LIKE HEAVY NECK MUSCLES.Punjab EDUSAT Society {PES}

STRUCTURE OF DNA• GENETIC MATERIAL IN ALL ORGANISMS.• IN PROKARYOTIC CELLS, DNA IS CIRCULAR &OCCURS IN CYTOPLASM.• IN EUKARYOTIC ORGANISMS, DNA LINEAR&LARGELY CONFINED TO NUCLEUS & SMALLQUANTITY IN MITOCHONDRIA.Punjab EDUSAT Society {PES}

• CHEMICAL STRUCTUREEXPLAINED BY P.A.LEVENE.• LARGEST MOLECULECOMPOSED OF LONGDOUBLE CHAIN OFDEOXYRIBONUCLEOTIDEUNITS.Punjab EDUSAT Society {PES}

STRUCTURE OF DNA• EACH DEOXYRIBONUCLEOTIDE UNIT HAS:• DEOXYRIBOSE SUGAR• NITROGEN BASES:• PURINES:ADENINE & GUANINE.• PYRIMIDINES:THYMINE & CYTOSINE.• PHOSPHORIC ACID• IN EACH DEOXYRIBONUCLEOTIDE UNIT, NITROGENBASE IS JOINED TO DEOXYRIBOSE SUGAR AT 1’CARBON ATOM.Punjab EDUSAT Society {PES}

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• IN EACH CHAIN PHOSPHATE CARRIED BY CARBON ATOM AT5’ OF SUGAR IN ONE NUCLEOTIDE UNIT JOINED BY PHOSPHODIESTER BOND TO HYDROXYL OF CARBON AT 3’ OF SUGARIN NEXT NUCLEOTIDE UNIT.Punjab EDUSAT Society {PES}

SALIENT FEATURES OF DOUBLE-HELIX ST. OF DNA• TWO POLYNUCLEOTIDE CHAINS HAVINGBACKBONE CONSTITUTED BY SUGAR- PHOSPHATE& BASES PROJECT INSIDE.• ANTI PARALLEL POLARITY OF TWO CHAINS.• BASES OF TWO STRANDS PAIRED BY H- BONDING.• TWO CHAINS COILED IN RIGHT HANDED FASHIONPunjab EDUSAT Society {PES}

Punjab EDUSAT Society {PES}

Punjab EDUSAT Society {PES}

WATSON AND CRICK MODEL• J.D. WATSON & F.H.C CRICKDESIGNED THE MODEL OFDNA FOR WHICH THEY GOTTHE NOBEL PRIZE IN 1962.• IT CONSISTS OF TWO LONGPARALLEL CHAINS WHICHARE JOINED TOGETHER BYSHORT CROSSBARS ATREGULAR INTERVALS.• TWO CHAINS SPIRALLYCOILD AROUND A COMMONAXIS TO FORM DOUBLEHELIX.• DIAMETER OF DOUBLE HELIXIS 20 A 0 &ONE COMPLETESPIRAL OF HELIX IS 34 A 0 HAS10 BASE PAIRSPunjab EDUSAT Society {PES}

CHARGAFF’S RULES• DNA MOLECULE ALWAYS HAS A-T =G-CBASE PAIRS.• PURINES ALWAYS IN EQUAL AMOUNT:• A+G=T+C• A=T &G=C• DEOXYRIBOSE SUGAR & PHOSPHATECOMPONENTS OCCUR IN EQUALPROPORTIONS.Punjab EDUSAT Society {PES}

TYPES OF DNA• LINEAR &CIRCULAR DNA:• LINEAR DNA HAS FREE ENDS & PRESENT IN EUKARYOTES.• CIRCULAR DNA HAS ENDS JOINED TOGETHER & PRESENT INPROKARYOTES.• TROPHIC & GENETIC DNA:• TROPHIC DNA PRESENT IN MACRONUCLEUS OF CILIATES• GENETIC DNA PRESENT IN MICRONUCLEUS OF CILIATESPunjab EDUSAT Society {PES}

A-,B-,C-,D-,Z-DNA:Punjab EDUSAT Society {PES}

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