5. chromosom mutations
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5. chromosom mutations

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BIOLOGY LECTURE DNMU

BIOLOGY LECTURE DNMU

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5. chromosom mutations 5. chromosom mutations Presentation Transcript

  • CHROMOSOMESMUTAIONS
  • PLAN OF LECTURE1. MUTATION AND ITS TYPES.2. CHROMOSOMAL ABERRATIONS:1)DELETION; 2) DUPLICATION; 3) INVERSION;4) TRANSLOCATION.3. GENOMIC MUTATION (CHROMOSOME MUTATION):1) POLYPLOIDY; 2) ANEUPLOIDY.4. AUTOSOMAL MUTATIONS.5. SEX-CHROMOSOMES MUTATIONS.
  • You should prepare for the practical classusing the existing textbook and lectureApplicable literature materials:Medical biology / K. L. Lasarev – Simferopol: IADCSMU, 2002 p.181 - 188.Key words and phrases:mutation, genomic mutation, polyploidy,aneuploidy, chromosomal aberrations, deletion,duplication, inversion, translocation, oncogene,aneuploidy (heteroploidy), euploidy (polyploidy),monosomy, trisomy, autosomal trisomic, sex-chromosome polysomy, monosomy X.
  • HEREDITARYINFORMATION LIESIN CHROMOSOMES.THE EUKARYOTICCHROMOSOMESARE LOCATED WITHINTHE NUCLEUS OF THECELL.
  • MUTATION VARIABILITY• MUTATION - A PERMANENT TRANSMISSIBLECHANGE IN THE GENETIC MATERIAL,MODIFICATION IN CHROMOSOMES AND GENES.• CHROMOSOMAL MUTATIONS MAY BE THERESULT OF CHANGES IN THE STRUCTURE ORNUMBER OF CHROMOSOMES.• THERE ARE 2 MAIN TYPES OF CHROMOSOMESMUTATIONS:
  • 1.CHROMOSOMAL ABERRATIONS - CHANGESIN STRUCTURE OF CHROMOSOMES.2.GENOMIC MUTATION - CHANGES INNUMBER OF CHROMOSOMES.CERTAIN FORMS OF CHROMOSOMALMUTATION MAY AFFECT SEVERAL GENES ANDHAVE A MORE PROFOUND EFFECT ON THEPHENOTYPE THAN GENE MUTATIONS.
  • CHROMOSOMAL ABERRATIONS - CHANGES INSTRUCTURE OF CHROMOSOMES
  • CHROMOSOMAL MUTATIONSOR ABERRATIONS
  • INVERSIONA SEGMENT OF A CHROMOSOME SEPARATESAND REJOINS IT IN AN INVERTED POSITION.INVERSION CHANGES THE SEQUENCE OFNITROGENOUS BASES IN THE CHROMOSOMES.INVERSION OCCURS WHEN A REGION OF ACHROMOSOME BREAKS OFF AND ROTATESTHROUGH 180° BEFORE REJOINING THECHROMOSOME.
  • INVERSIONNO CHANGE IN GENOTYPE OCCURS AS ARESULT OF INVERSION BUT PHENOTYPICCHANGES MAY BE SEEN.THIS SUGGESTS THAT THE ORDER OF GENELOCI ON THE CHROMOSOME IS IMPORTANT, APHENOMENON KNOWN AS THEPOSITION EFFECT.
  • TRANSLOCATIONA SEGMENT OF CHROMOSOME BREAKSOFF AND JOINS A NONHOMOLOGOUSCHROMOSOME.BOTH THE AFFECTED CHROMOSOMESGET MODIFIED. THE DONOR SUFFERSDELETION AND BECOMES SHORTERTHAN NORMAL. THE RECIPIENT HAS ANEXTRA SET OF GENES AND BECOMESLONGER THAN NORMAL.
  • RECIPROCAL TRANSLOCATIONRECIPROCAL TRANSLOCATION BETWEENNONHOMOLOGOUS CHROMOSOMES CANPRODUCE TWO NEW HOMOLOGOUS PAIRSOF CHROMOSOMES.
  • ROBERTSONIAN TRANSLOCATIONROBERTSONIAN TRANSLOCATION –SPECIAL SORT WHERE THERE ISNONRECIPROCAL EXCHANGES OF DNA,FUSION OF TWO ACROCENTRICS TO GIVEA METACENTRIC, CENTROMERIC FUSION.
  • ROBERTSONIAN TRANSLOCATION
  • IN SOME CASES OF DOWNS SYNDROME, WHERE THE DIPLOIDNUMBER IS NORMAL, THE EFFECTS ARE PRODUCED BY THETRANSLOCATION OF AN EXTRA 21 CHROMOSOME ONTO ALARGER CHROMOSOME, USUALLY 13,14,15.
  • DELETIONA SEGMENT OF A CHROMOSOMESEPARATES AND IS LOST.THE AFFECTED CHROMOSOME LOSESCERTAIN GENES, AND BECOMES SHORTERTHAN NORMAL.IF DELETION AFFECTS THE SAME GENE LOCION BOTH HOMOLOGOUS CHROMOSOMES THEEFFECT IS USUALLY LETHAL.
  • DUPLICATIONA FRAGMENT OF A CHROMOSOMEJOINS A HOMOLOGOUS CHROMOSOME.THE ADDITIONAL REGION OF GENESMAY BE INCORPORATED WITHIN THECHROMOSOME OR AT ONE END OF THECHROMOSOME, OR BECOME ATTACHED TOANOTHER CHROMOSOME.THESE CHANGES, IF NOT LETHAL, MAYCAUSE PROFOUND CHANGES IN THEPHENOTYPE.
  • CHROMOSOME ABNORMALITIES AND CANCERTRANSLOCATIONS AND INVERSIONS CREATENEW ARRANGEMENTS OF GENES, SOMEGENES ARE MORE HIGHLY EXPRESSED ORARE MUCH LESS EXPRESSED, THERE ARE"POSITION EFFECTS" ON GENE EXPRESSION,SOME OF THESE CHANGES LEAD TOCANCER, OVEREXPRESSION OF ANONCOGENE OR UNDEREXPRESSION OF ATUMOR SUPPRESSOR GENE CAN LEAD TOCANCER.
  • CHROMOSOME ABNORMALITIES AND CANCER
  • GENOMIC MUTATIONCHANGES IN THE NUMBER OFCHROMOSOMES ARE USUALLY THERESULT OF ERRORS OCCURRINGDURING MEIOSIS BUT THEY CAN ALSOOCCUR DURING MITOSIS. THESECHANGES MAY INVOLVE THE LOSS ORGAIN OF SINGLE CHROMOSOMES, ACONDITION CALLED ANEUPLOIDY ORHETEROPLOIDY.
  • ANEUPLOIDY - HETEROPLOIDYMONOSOMY – LOSS OF A CHROMOSOME,SO A "DIPLOID -1" , HAS ONLY ONE COPYOF A PARTICULAR CHROMOSOME RATHERTHEN TWO.EXAMPLE: MONOSOMIC (2N-1), 45(X0)TRISOMY – GAIN OF A CHROMOSOME SOTHERE ARE THREE OF ONE SORT/EXAMPLE: TRISOMIC (2N+1), 47 (XXX)
  • SEX-CHROMOSOMES MUTATIONSANEUPLOIDY IS THE LOSS OR GAIN OFSINGLE CHROMOSOMES, NUMERALCHANGES (ANEUPLOIDY) IN SEXCHROMOSOMES.SEX-CHROMOSOME POLYSOMYA. TRIPLE X: (47, XXX); TRISOMY X;FEMALE.B. DOUBLE Y: (47,XYY); TRISOMY; DISOMYY; MALE.
  • C. KLINEFELTER SYNDROME; (47, XXY);TRISOMY; MALE.THESE INDIVIDUALS TEND TO BE TALL,STERILE, WITH MILD MENTAL RETARDATIOND. TURNER SYNDROME; (45, XO);MONOSOMY X; FEMALE.THESE INDIVIDUALS TEND TO BE SHORT,STERILE, WITH NORMAL MENTALDEVELOPMENT
  • Sex-chromosome polysomya. triple X: (47, XXX); trisomy X;
  • POLYPLOIDYTHE INCREASE IN ENTIRE HAPLOIDSETS OF CHROMOSOMES, ACONDITION CALLED POLYPLOIDY.MONOPLOID CHROMOSOME SET1N – THE BASIC CHROMOSOME SETOF A SPECIES.
  • POLYPLOIDY, HAVING A PERFECT,BALANCED CHROMOSOMECOMPLEMENT.HUMAN TRIPLOIDS 3N=69 ANDTETRAPLOIDS 4N=92 ARE NOTVIABLE. POLYPLOID HUMANEMBRION DIE. BUT TETRAPLOIDCELLS IN NORMAL MAY BE IN HUMANLIVER.
  • AUTOPOLYPLOIDY
  • MOSAICISM
  • TWO TYPES OF MOSAICISM
  • MOSAICISM
  • MOSAICISM
  • DO YOU HAVEA QUESTIONES?THE END