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  • 1.
  • 2.
      BIOLOGY WORK Teacher: González Montero, Jose María Realized by: Daniela Nicoletta Trinc María Espinosa García de la Serrana 2010
  • 3. DNA
  • 4.  
  • 12. History
    • In 1869 biologist Johann Friedrich Miesscher separated the cell membrane and cytoplasm of the cell to isolate the cell nucleus and identified a new group of cellular substances which he called nuclein.
  • 13.
    • Subsequently,Richard
    • 14. Altmann identified the
    • 15. acids and gave them
    • 16. the name nucleic
    • 17. acids.
  • 18.
    • Robert Feulgen, in 1914, described a method to reveal by staining the DNA, based on the dye fuchsin. Using this method, the presence of DNA in the nucleus of all eukaryotic cells, specifically in chromosomes.
  • 19.
    • During the 20s, the biochemist P.A. Levene examined the components of DNA, nucleic acids and found that it contained four nitrogenous bases: cytosine and thymine, adenine and guanine, the sugar deoxyribose and a phosphate group.
  • 20.
    • He showed that they were united in the order phosphate-sugar-base, forming what he called a nucleotide. Levene also suggested that the nucleotides were linked by forming the DNA phosphates.
  • 21.
  • 29.
    • A year after the Hershey-Chase experiments appeared in the journal Nature, a joint article by Watson and Crick story recounting the discovery they had made (DNA) .
  • 30. STRUCTURE Each DNA molecule consists of two chains formed by a large number of chemical compounds called nucleotides .
  • 31. Each nucleotide consists of three units: a sugar molecule (desoxyribose), a phosphate group and one of four possible nitrogen compounds called bases: adenine (A), guanine (G), thymine (T) and cytosine (C).
  • 32. Containing adenine nucleotides are coupled always with thymine, and cytosine with guanine. The complementary bases are joined together by weak chemical bonds called hydrogen bonds .
  • 33. Deoxyribonucleic acid is a polymer of two antiparallel strands (orientation 5 '3'y3'5').
  • 34. REPLICATION The DNA replication process allows the DNA to double, ie, synthesize an identical copy.
  • 35. This duplication of genetic material occurs according to a semiconservative mechanism(the chain of the DNA is previous ).
  • 36.
      The process of Replication begins with the helicase , an vital enzyme . (The human being have got 24 enzymes). Its mission is to break the hydrogen bonds.
  • 37. DNA polymerases give each daughter cell a DNA copy of the original in the process of mitosis. They carry out the synthesis of new DNA strand matching the deoxyribonucleotide triphosphate.
  • 38. Primer is a iniciator of the creation of the chain delayed (so called because its direction is 3-5).
  • 39. DNA polymerase III is the principal responsible enzyme for DNA elongation (polymerase activity 5 '-> 3'). It also performs tasks of correction (exonuclease activity 3 '-> 5').
  • 40. DNA polymerase | (adds 20 to 100 nucleotides per binding event) is responsible for the elimination of primers and the "filling" the space left by DNA.
  • 41. DNA ligase is a enzyme with forms links between 5 'end of a chain end and 3 'of another string.
  • 42. Gene expression DNA -> RNA -> protein: gene expression. To express the genetic information contained in DNA, first the nucleotide sequence of a gene is transcribed into RNA. The transcript is catalyzed by the enzyme RNA polymerase.
  • 43. The sequences of the nucleotids of DNA's molecules indicate to RNA polymerasa where to start and where to finish the transcription.
  • 44.
      The difference between DNA and RNA: It contains the sugar ribose instead of deoxyribose. It contains the base uracil (U) instead of thymine (T)
  • 45. Kind of RNA
      mRNA ---> protein coding rRNA --->part of the ribosome structure. Participates in the synthesis of proteins. tRNA --->participates in the synthesis of the proteins as an adapter.
  • 46. Most genes are divided into small coding regions (exons) interspersed with noncoding regions (introns) .
  • 47. At the core, the introns are removed from the primary RNA transcript through a process of maturation of RNA. By a reaction catalyzed by small ribonucleoprotein complexes known as snRNPs, the introns are excised from the primary transcript and exons are joined together directly. Then the mRNA moves to cytoplasm.
  • 48. The nucleotide sequence of the mRNA is read in groups of three nucleotides ( codons ), so that each codon corresponds to an aminoacid.
  • 49. The possible combinations of four different nucleotides in the RNA produced 64 different codons in the genetic code. Most amino acids are specified by more than one codon.
  • 50.  
  • 51.
    • The replication must be exactly the same,if it´s not, a lot of illnesses can be developed.
  • 52.
    • Alterations of genetic material.
    • 53. TYPES : gene, chromosome and numerical.
    • 54. Gene: affects the chemical structure of genes.
  • 55.
    • Chromosomal mutations : affects chromosome structure.
    • 56. Types:
    • 57. a) Deletion b) Duplication
  • 58.
      c) Investment d) Translocation with another chromosome
  • 59. Numerical: The disorder affects the number of chromosomes. There are two types: euploidias: affect the number of chromosomes: aneuploidy : missing or overrun chromosomes.
  • 60. Causes of mutations Mutagenic agents can be: physical (X-ray,radiation) chemicals (pesticidios, dyes, smoke snuff) biological (human papillomavirus)
  • 61. Autosomal disorders Dominant alleles: Polydactyly Syndactyly Brachydactyly
  • 62. Recessive alleles: Albinism Anemia
  • 63. Autosomal disorders The most frequent are trisomies. Down syndrome (trisomy 21): Features: Mental retardation Mongoloid facial features Various disorders (eye, heart ...)
  • 64. Edwards syndrome (trisomy 18):
    Profound mental deficiecia Renal and cardiac malformations Stunting Short neck
  • 65. Patau syndrome(trisomy 13): Features: Mental retardation Cardiac malformations Absence of palate
  • 66. Sex chromosomes Women are affected: Triple X syndrome (3 X) Features: Mental retardation Neuropsychiatric disorders
  • 67.
      Turner syndrome(X) Features:
    Children's genitals Short stature
  • 68. Men are affected: Double Y syndrome(Y and 2X) Features: Skeletal malformations Mild mental retardation
  • 69.
      Klinefelter syndrome(2X and Y): Features:
    Mental retardation Small genitals
  • 70.
    • “ Cri du chat” syndrome
    • 71. Features:
    • 72. Produces heart failure and microcephaly, profound mental retardation.
  • 73. VIDEO
  • 74. Bibliography
    • Wikipedia
    • 75. Information sent by the teacher Biology and Geology(oxford education) 4º E.S.O.
  • 76. Images Information sent by the teacherç