Bio Ch 15 genes and how they work

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Author:
tjtolman
ID:
141773
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Bio Ch 15 genes and how they work
Updated:
2012-03-18 22:08:50
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bio
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central dogma / genes and how they work
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  1. Central dogma
    • what is the connection btwn mendelian genetics (traits) and molecular genetics
    • One gene - one enzyme (trait) hypotheisis

    • Main topics of bio:
    • 1) Central Dogma
    • 2) Evolution
    • 3) Cell theory
  2. sequence of central dogma:
    DNA in nucleus---transcription (copied into mRNA)---> message-----translation (goes to cytoplasm)----> Makes protien

    Sequence of nucleotides---seq of amino acids
  3. Sequence of nucleotides:
    • DNA.....CGC....
    • mRNA....GCG....
    • Protein ......a.a......
    • Nucleotide language - 4 types (A,C,G,T)
    • Amino acid language- 20 types
    • Triplets of nucleotides: ATA, CGA..... 64 (on DNA)
    • "genetic code" - mRNA tirplets (codons)
  4. Transcription:
    DNA in nucleus--->mRNA goes to cytoplasm
  5. RNA in general:
    • Nucleic acid-
    • 1) usually single stranded
    • 2) has U instead of T
    • 3) has ribose not deoxyribose as sugar
  6. mRNA:
    • messenger RNA
    • carries genetic info
    • Relatively long (few 100 - 10,000 nucl. long)
    • 3 adjacent nucleotides (codons)
  7. Transcription process:
    • main enzyme: RNA polymerase
    • 50 nucl/sec added to make mRNA
    • Starts at prommoter site on DNA

    • 1) RNA polymerase recognizes and attaches to promoter
    • 2) DNA helix opens into transcription bubble (12 nucl. long (short)
    • 3) RNA nucl added
    • Ends at termination (no proof reading - can have mistakes)
  8. Final product from transcription in Prokarytoes and Eukaryotes:
    Prokarytoes: final product is mRNA (used)

    Eukarytoes: DNA---> Trancription---> Primary mRNA trancript---> Modified ---> Mature mRNA
  9. Modifications mRNA:
    "posttranscriptional modifications" (eukaryotes)

    1) 5prime cap (proteced) ----mRNA---2)3prime tail (protects)

    • 3) removal of "introns" (genes have .5 introns
    • Spliceosomes - snips introns
    • Human DNA- 24% introns
  10. Translation:
    • Process by when mRNA made into protein (expensive)
    • -Done on ribosomes
    • tRNA (transfer DNA) transfers an amino acid (15% of cellular RNA)
  11. Enzymes that attach the correct a.a. to the tRNA:
    Aminoacyl-trna synthotasses (charged tRNA)
  12. rRNA:
    • Ribosomal RNA- helps make up ribosome
    • Ribosome= preotein and rRNA
  13. Translation as a process:
    • mRNA---> protein (fmet)
    • Complimentary anticodon attaches to:
    • initiation mRNA that has:
    • (E,P,A sites)
    • A: amino acid site
    • P: peptidyl *peptide bond forms
    • E: exit site'
  14. Elongation and Translocation:
  15. Translation Prokayotes vs Eukaryotes:
    • Prokaryotes:
    • not modifed
    • Ribosomes are different
    • Group of genes,group of mRNA, group of proteins

    • Eukaryotes:
    • Initial mRNA modified
    • 1 gene=1mRNA=1protein
  16. Mutations:
    • Change in genetic content
    • 50 ml result from a change in location of gen. location
    • negative affect
    • some positive (fuel for natural selection)
    • neutral
  17. Point mutation:
    • few nucleotides affected
    • causes: mutagens (chemicals or radiation)
    • Mistakes in nucleotide pairing (mistake in DNA)

    • a) base substitution ATA ---> ACA
    • b) insertioin ATA---> ATTA (insert nucleotide)
    • c) deletion ATA----> AA (delete nucleotide)
    • (b and c are "frame shift mutations"
    • d) Nonsense mutation -change to stop codon
    • e) triplet repeat expansion mutation (20 diseases known)
    • *book
  18. Chromosomal mutation:
    • Large section of chromosome involved
    • eg: deletion
    • eg: duplication
    • eg: inversion
    • etc....
  19. Mutations from change in location of genetic info:
    • Transportion
    • transposone
    • jumping genes
    • a gene jumps randomly
  20. Causes of mutation:
    • 1) physical damage by ionizing radiation
    • (xrays, gamma rays) create and rfree radicals (ionized)
    • very reactive w/ other molecules

    • 2) physical damage by T & C
    • 2 adjacent T's will bind abnormally to eachother
    • -sunlight (uvlight) -->mutations-->cancer

    3) chemical modifications of DNA
  21. Control of gene expression/ how is gene regulation organized?
    • a) at initiation of transcription (affecting whether RNA polymere can bind to promoter
    • b) processing of mRNA (introns/exrons)
    • c) Transport of mRNA out of nucleus (selective)
    • d) half-life of mRNA
    • e) small RNA's - interact w/ mRNA and inhibit mRNA action
    • f) protein sythesis
    • g) post transcriptional modifications
  22. why is gene expression regualted:
    1) prokayotes- variable envrionment (not in control of environment) (environement dependent)

    2) eukaryotes - homeostasis, multicellular issues, dev. into multicellular
  23. Transcriptional control (regulation)
    • Transcriptional factors (proteins) attach in regulatory region and or inhibit RNA polymere action.
    • RNA polymeraes --onto promoter--- onto regulatory region... get a mRNA

    5prime......Regulatory region..Coding Region............3prime
  24. DNA sequence of nucleotides:
    CGC
  25. mRNA sequence:
    GCG
  26. Protein sequence:
    a.a.
  27. Nucleotide language:
    • ATCG
    • A=T
    • C=G
  28. a.a. language:
    20 types
  29. Triplet of nucleotides:
    ATA, CGA... (64 on DNA)
  30. Genetic Code:
    mRNA triplets (CODONS)
  31. mRNA tiplet
    Codon
  32. Genes have how many introns?
    5
  33. Human DNA has how many introns?
    24%
  34. 3 stages of translation:
    • 1)initiation
    • 2)elongation
    • 3) termination
  35. Components of translation:
    • mRNA
    • Ribosome (small/big)
    • tRNA
    • release factor
  36. Pic of translation:
  37. Translation process:
    • 5 to 3 prime mRNA
    • 5 prime cap
    • Small subunit ribosome goes to initiation site
    • trna with anticodon attaches to codon on mRNA
    • Psite 1st site, A site second
    • growing peptide(protein) continues until stop codon...
    • Release factor releases everything
  38. Transcription:
    Exact copy
  39. Translating:
    translated to protein language
  40. Template strand:
    strand being copied
  41. coding strand:
    strand not being used
  42. Start codon/stop codon
    • start: AUG
    • stop: UAA, UGA, UAG
  43. Transcription:
    • starts at promoter
    • Transcription bubble opens up.. loccally unwound DNA
    • Translation and transcription coupled

    (transcription factors)
  44. tRNA binding sites:
    • EPA
    • Exit
    • Primary
    • Acetly - secondary
  45. Transcription pic:

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