La Molécula de AND y los Procesos de Transcripción y Traducción

Transcription

1 La Molécula de ND y los Procesos de Transcripción y Traducción MSP 21-Superior Enero-Mayo-2017 Prof. Tacher

2 Objetivos Describir la estructura de la molécula de DN Establecer la importancia del código genético. Describir los procesos de transcripción y traducción de la molécula de DN. Establecer las consecuencias de las mutaciones en el DN.

3 Estándar: Estructura y Niveles de Organización de la Materia Indicadores Relevantes: ES.B.B1.EM.3 : Explica, utilizando evidencia cienti fica, de co mo la estructura del DN determina la estructura de las protei nas que llevan a cabo las funciones esenciales de la vida por medio de sistemas de ce lulas especializadas. ES.B.B3.EM.1: Formula preguntas para aclarar las relaciones del rol del DN y de los cromosomas en la codificacio n de las instrucciones para las variaciones de las caracteri sticas que pasan de una generacio n a otra.

4 Estándar: onservación y ambio Indicadores Relevantes: ES.B.B3..1:Formula y defiende una afirmacio n basada en evidencia, de que las variaciones gene ticas y hereditarias pueden resultar de: (1) nueva combinacio n gene tica mediante el proceso de meiosis, (2) errores viables pueden ocurrir durante la replicacio n del DN y/o (3) las mutaciones a causa de los factores ambientales. El e nfasis esta en el uso de datos para apoyar argumentos sobre las diferentes formas en que pueden ocurrir las mutaciones.

5 Figure 1

6 Figure 2 (a) Rosalind Franklin (b) Franklin s X-ray diffraction photograph of DN

7 Figure 3 Sugar phosphate backbone end Nitrogenous bases Thymine (T) denine () ytosine () end DN nucleotide Guanine (G)

8 Figure 4 G G G G end Hydrogen bond T end T 3.4 nm G G G T 1 nm T G G G G T T T T 0.34 nm end end (a) Key features of DN structure (b) Partial chemical structure (c) Space-filling model

9 Figure 5 G G G G T 3.4 nm G G T 1 nm T G G G T T T 0.34 nm (a) Key features of DN structure

10 Figure 6 end Hydrogen bond end T G G T end (b) Partial chemical structure end

11 Figure 7 DN double helix (2 nm in diameter) Nucleosome (10 nm in diameter) 30-nm fiber hromatid (700 nm) Loops Scaffold Histones Histone tail H1 300-nm fiber Replicated chromosome (1,400 nm)

12 Figure 8 DN double helix (2 nm in diameter) Nucleosome (10 nm in diameter) Histones Histone tail H1

13 Figure 9 hromatid (700 nm) 30-nm fiber Loops Scaffold 300-nm fiber Replicated chromosome (1,400 nm)

14 De Gen a Proteína (Procesos de Transcripción y Traducción)

15 Figure 10

16 Fig 11

17 Fig.12

18 Fig.13

19 Figure 15a Nuclear envelope TRNSRIPTION DN Pre-mRN (b) Eukaryotic cell

20 Figure 15-b Nuclear envelope TRNSRIPTION DN RN PROESSING Pre-mRN mrn (b) Eukaryotic cell

21 Figure 15-c Nuclear envelope TRNSRIPTION DN RN PROESSING Pre-mRN mrn TRNSLTION Ribosome Polypeptide (b) Eukaryotic cell

22 Fig. 15-d DN molecule Gene 1 Gene 2 Gene 3 DN template strand TRNSRIPTION mrn odon TRNSLTION Protein mino acid

23 Fig 16: Lista de minoácidos

24 First mrn base ( end of codon) Third mrn base ( end of codon) Figure 17 Second mrn base U G U UUU UU UU UUG Phe Leu UU U U UG Ser UU U U UG Tyr Stop Stop UGU UG UG UGG ys Stop Trp U G UU U U UG Leu U G Pro U G His Gln GU G G GG rg U G UU U U UG IIe Met or start U G Thr U G sn Lys GU G G GG Ser rg U G G GUU GU GU GUG Val GU G G GG la GU G G GG sp Glu GGU GG GG GGG Gly U G

25 Figure 18-a Promoter Transcription unit 1 Initiation Start point RN polymerase Unwound DN RN Template strand of DN transcript

26 Figure 18-b Promoter Transcription unit 1 Initiation Start point RN polymerase 2 Elongation Unwound DN Rewound DN RN transcript RN Template strand of DN transcript Direction of transcription ( downstream )

27 Figure 18-c Promoter Transcription unit 1 Initiation Start point RN polymerase 2 3 Elongation Termination Unwound DN Rewound DN RN transcript RN Template strand of DN transcript ompleted RN transcript Direction of transcription ( downstream )

28 Figure 19 DN T T T T T T T TT box Promoter Transcription factors Start point Nontemplate strand Template strand 1 eukaryotic promoter 2 Several transcription factors bind to DN. RN polymerase II Transcription factors 3 Transcription initiation complex forms. Transcription initiation complex RN transcript

29 Figure 20 RN polymerase Nontemplate strand of DN RN nucleotides T end U T G G T T Newly made RN Direction of transcription Template strand of DN

30 Promoter Transcription unit 1 Initiation Start point RN polymerase 2 3 Elongation Termination Unwound DN Rewound DN RN transcript RN Template strand of DN transcript ompleted RN transcript Direction of transcription ( downstream )

31 Figure 21 modified guanine nucleotide added to the end G P Protein-coding segment P P U adenine nucleotides added to the end Polyadenylation signal Start Stop ap UTR UTR Poly- tail codon codon

32 Figure 22 Pre-mRN ap Intron mrn Intron Introns cut out and exons spliced together Poly- tail ap UTR oding segment Poly- tail UTR U

33 Fig. 23-a RN transcript (pre-mrn) Exon 1 Intron Exon 2 Protein snrn snrnps Other proteins

34 Fig. 23-b RN transcript (pre-mrn) Exon 1 Intron Exon 2 Protein snrn snrnps Other proteins Spliceosome

35 Fig. 23-c RN transcript (pre-mrn) Exon 1 Intron Exon 2 Protein snrn snrnps Spliceosome Other proteins Spliceosome components mrn Exon 1 Exon 2 ut-out intron

36 Práctica de Transcripción

37 Práctica de Transcripción

38 Práctica de Transcripción 1 DN T T T RNm U G G U U U

39 Práctica de Transcripción 2 DN G T G G RNm

40 Práctica de Transcripción 2 DN G T G G RNm G G G U U

41 Proceso de Traducción De RNm a Proteína

42 Fig 24-a Molécula de RNt

43 Figure 24-b Polypeptide mino acids Ribosome trn with amino acid attached Gly U G G U U U G G trn nticodon mrn odons

44 Figure 25 P site (Peptidyl-tRN binding site) E site (Exit site) mrn binding site Exit tunnel site (minoacyltrn binding site) E P Large subunit Small subunit (b) Schematic model showing binding sites

45 Figure 26 U U G P site Large ribosomal subunit Initiator trn mrn GTP Start codon Small mrn binding site ribosomal subunit 1 Small ribosomal subunit binds to mrn. 2 P i GDP E Translation initiation complex Large ribosomal subunit completes the initiation complex.

46 Figure 27-a mino end of polypeptide 1 odon recognition mrn E P site site GTP GDP P i E P

47 Figure 27-b mino end of polypeptide 1 odon recognition mrn E P site site GTP GDP P i E P 2 Peptide bond formation E P

48 Figure 27-c mino end of polypeptide 1 odon recognition Ribosome ready for next aminoacyl trn mrn E P site site GTP GDP P i E E P P 3 Translocation GDP P i GTP 2 Peptide bond formation E P

49 Figure 28-a Release factor 1 Stop codon (UG, U, or UG) Ribosome reaches a stop codon on mrn.

50 Figure 28-b Release factor Free polypeptide Stop codon (UG, U, or UG) 1 Ribosome reaches a stop codon on mrn. 2 Release factor promotes hydrolysis.

51 Figure 28-c Release factor Free polypeptide 1 Stop codon (UG, U, or UG) Ribosome reaches a stop codon on mrn. 2 GTP 2 Release factor 3 promotes hydrolysis. 2 GDP P i Ribosomal subunits and other components dissociate.

52 Figure 29 Growing polypeptides ompleted polypeptide Incoming ribosomal subunits Start of mrn ( end) End of mrn ( end) (a) Several ribosomes simultaneously translating one mrn molecule Ribosomes mrn (b) large polyribosome in a bacterial cell (TEM) 0.1 m

53 Figure 30 TRNSRIPTION DN RN transcript RN PROESSING YTOPLSM Exon NULEUS RN polymerase RN transcript (pre-mrn) Intron mino acid trn minoacyl-trn synthetase MINO ID TIVTION mrn E P Ribosomal subunits minoacyl (charged) trn TRNSLTION E U G G U U U U G nticodon Ribosome odon

54 Figure 31-a Nucleus Rough ER Smooth ER Plasma membrane

55 Figure 31-b Nucleus Rough ER Smooth ER cis Golgi trans Golgi Plasma membrane

56 Figure 31-c Nucleus Rough ER Smooth ER cis Golgi trans Golgi Plasma membrane

57 Práctica de traducción

58 Práctica de traducción

59 Práctica

60 Práctica

61 Figure 32 Wild-type hemoglobin Sickle-cell hemoglobin Wild-type hemoglobin DN T G G Mutant hemoglobin DN G T G mrn G G mrn G U G Normal hemoglobin Glu Sickle-cell hemoglobin Val

62 Figure 33

63 Figure 34 T T Met DN template strand T mrn Protein mino end (a) Nucleotide-pair substitution Lys Phe Gly T T G T T T G G T T T G G T U G G U U U G G U Met T T T T T G G T T T G G T T U G G U U U G G U U Stop Silent (no effect on amino acid sequence) T T T G T T T G G T T T G T U G G U U U G U Met Missense Lys T T U instead of U G G Met Nonsense instead of T Phe Ser T G T T G T G T T T G G T U U U U G G U U Stop instead of G U instead of T instead of instead of G Stop Wild type Lys Phe T T T Gly Met Stop arboxyl end (b) Nucleotide-pair insertion or deletion Extra T T G T T G T G T T T G G T U G U G U U U G G U U T T G T T T G G T T G G T U G G U U G G G U Met Met Extra U Stop Frameshift causing immediate nonsense (1 nucleotide-pair insertion) T T Lys Phe U Leu G Gly la Frameshift causing extensive missense (1 nucleotide-pair deletion) T G T T T G G T G missing missing missing missing U G U U U G G U T T Stop No frameshift, but one amino acid missing (3 nucleotide-pair deletion) T

64 Figure 34-a Wild type DN template strand mrn Protein mino end T T T G T T T G G T T T G G T U G G U U U G G U Met Lys Phe Gly Stop arboxyl end Nucleotide-pair substitution: silent instead of G T T T T T T G G T T T G G T T Met Lys Phe Gly U instead of U G G U U U G G U U Stop

65 Figure 34-b Wild type DN template strand mrn Protein mino end T T T G T T T G G T T T G G T U G G U U U G G U Met Lys Phe Gly Stop arboxyl end Nucleotide-pair substitution: missense Met Lys T instead of T T T T G T T T G G T T T G T instead of G U G G U U U G U Phe Ser Stop

66 Figure 34-c Wild type DN template strand mrn Protein mino end T T T G T T T G G T T T G G T U G G U U U G G U Met Lys Phe Gly Stop arboxyl end Nucleotide-pair substitution: nonsense instead of T T T G T T T G T G T T T G G T U instead of U G U G U U U G G U Met Stop

67 Figure 34-d Wild type DN template strand mrn Protein mino end T T T G T T T G G T T T G G T U G G U U U G G U Met Lys Phe Gly Stop arboxyl end Nucleotide-pair insertion: frameshift causing immediate nonsense Extra T T T G T T T G T G T T T G G T Met Extra U U G U G U U U G G U Stop

68 Figure 34-e Wild type DN template strand mrn Protein mino end T T T G T T T G G T T T G G T U G G U U U G G U Met Lys Phe Gly Stop arboxyl end Nucleotide-pair deletion: frameshift causing extensive missense U missing T T T G T T T G G T T G G T missing U G G U U G G U Met Lys Leu la