bio181test4

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bandgeek1122
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52811
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bio181test4
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2010-12-02 00:15:58
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biology
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  1. Pedigree
    records genetic relationships among the individuals in a family along with each person's sex and phenotype with respect to the trait in question
  2. trait due to autosomal recessive allele
    • individuals with trait must be homozygous
    • if parent of affected do not have trait, parents heterozygous
  3. if males are more likely to have the trait in question, then
    allele responsible is likely to be ressive and found on the x chromosome
  4. the appearance of an e-linked recessive trait
    skips a gemeration in a pedigree
  5. Genes are made of
    DNA
  6. Hershey-Chase Experiment
    studied how virus T2 infects E.Coli, to determine if genes made of DNA or protein by seeing what T2 had enter host cell. Showed that DNA is hereditary material
  7. structure of DNA
    made of monomers called deoxyribonucleotides (have deoxyribose, sugar, molecule, phosphate group, nitrogenous base. Link into polymer wed phosphidiester bond forms between hydroxyl group on 3' carbon and phosphate to 5' carbon
  8. A strand of DNA has
    polarity (directionality) one end has exposed hydroxyl group on 3' carbon of deoxyribose, other has exposed phosphate group on 5' carbon.
  9. semiconservative replication
    each new daughter DNA molecule consist of one old and one new. (One strand used as template for synthesis of new)
  10. conservative replication
    results in intact parental molecule and a daughter DNA consisting of newly synthesized strands. ( strands toward outwear to serve as template, then turn back)
  11. Dispersivee replication
    parent helix cut into short sections before being unwound and copied, new and old segment alternate. old dan with new dan
  12. Meselson-Stahl Experiment
    • tested to see how DNA replicated using different isotopes of nitrogen. if conservative, daughter cells have either 14N or 15N, not both.
    • If semiconservative or dispersive, all DNA contain equal mix.
    • second generation-semiconservative have only have 14N, dispersive just one band
    • show that DNA molecule comprises one old strand and one new strand (semiconservative)
  13. DNA polymerase
    polymerized deoxyribonucleotides to DNA. can add deoxyribonucleotides to only 3' end of a growing DNA chain, DNA synthesis always proceeds from 5' -> 3'
  14. origin of replication
    site on a chromosome at which DNA replication begins
  15. replicatio fork
    Y-shaped region where parent DNA double helix is split into two single strands , which are then copied
  16. polymerization of DNA molecule is expergonic because the monomers are
    deoxyribonuclepside triphosphate
  17. helicase
    breakes hydrogen bonds between base pairs, causing DNA strands to separate
  18. Single-strand DNA-binding proteins (SSBPs)
    attach to separated strands and prevent them from snapping back into a double helix
  19. topoisomerase
    enzyme that cuts DNA, allows it to unwind, and rejoins it ahead of the advancing replication fork. relieves twisting forces caused by the opening off the helix
  20. primer
    required by DNA polymerase, consists of a few nucleotides bonded to template strand, provides free 3' hydroxyl group that can combine with an incoming dNTP to form phosphodiester bond
  21. primes leading
    catalyzes the synthesis of the RNA primer ( type of RNA polymers)
  22. RNA polymerase
    enzyme that catalyzes the polymerization of ribonucleotides into RNA, not need primers
  23. leading strand
    (continuously synthesized) 3' to 5' strand (synthesized 5' to 3')
  24. lagging strand
    synthesized in opposite direction of replication fork (5' to 3' strand of DNA) synthesized discontinuously
  25. synthesis of lagging strand
    starts when primes synthesizes short stretch of RNA for primer, DNA polymerase III adds base to 3' end of primer
  26. okazaki fragments
    short segment of DNA produced during replication of 5' to 3' template strand. make up lagging strand in newly synthesized DNA
  27. DNA polymerase III leading
    extends leading strand
  28. sliding clamp leading
    Holds DNA polymerase in place during strand extension
  29. primase in lagging strand
    catalyzes synthesis of RNA primer on okozaki fragment
  30. DNA polymerase III lagging
    extends Okazaki fragment
  31. sliding clamp lagging
    holds DNA polymerase in place during strand extension
  32. DNA polymerase I lagging
    removes RNA primer and replaces it with DNA
  33. DNA ligase lagging
    Catalyzes joining of Okazaki fragments into continuous strand
  34. telomere
    • region at the end of chromosome, do not contain genes that code for products needed in the cell
    • single stranded DNA remains after telomeres degrade, result in shortening of linear chromosomes
  35. telomerase
    catalyzes synthesis of DNA from RNA template
  36. ____ lacks telomerase
    somatic cells
  37. DNA polymerase III can ___ new strand
    proofread (done by epsilon subunit, acts as exonuclease and removes wrong nucleotide if -OH group is free)
  38. mismatch repair
    occurs when mismatched bases are corrected after DNA synthesis is complete. (other group of enzymes complete)
  39. nucleotide excision repair
    genes are under chemical attack, radiation, ect (nucleotides excision, followed by replacement and linkage)
  40. alleles that do not function
    knock-out,null, or loss of function alleles
  41. one-gene, one-enzyme hypothesis
    (Beadle and Tatum) claimed that genes contain information needed to make proteins, many of which function as enzymes.
  42. messenger rna (mRNA)
    RNA molecule that carries encoded info, transcribed from DNA, that specifies the amino acid sequence of a polypeptide
  43. RNA polymerase
    synthesizes RNA molecules according to the information provided by the sequence of bases in a particular stretch of DNA
  44. central dogma
    • summarizes flow of information in cells ( DNA -> RNA -> Proteins)
    • DNA is hereditary, Genes consist of stretches of DNA that code for products used, sequence of bases in DNA specify sequence of bases in RNA, sequence of bases in RNA specify sequence of amino acids in the protein, in this way genes code for proteins
  45. transcription
    process by which permanent info found in the DNA molecule is copied to the short-life information carrier molecule, mRNA
  46. translation
    process by which information contained in RNA molecule is transferred to type of molecule (protein)
  47. organism genotype is determined by
    sequence of bases in its DNA
  48. phenotype is a product of
    proteins it produces
  49. variations in phenotypes that we observe depend in part on
    variation in DNA sequences
  50. redundant genetic code
    more than one codon might specify same amino acid
  51. genetic code unambiguous
    codon never codes for more than one amino acid
  52. genetic code is nearly universal
    with few minor exceptions, all codons specify the same amino acids in all organisms
  53. point mutation
    single base change
  54. missense mutation
    point mutation that causes a change in the amino acid sequence of a protein (replacement mutation) can be beneficial neutral or deleterious
  55. silent mutation
    mutation that does not detectable affect the phenotype of the organism (usually neutral)
  56. nonsense mutation
    change in nucleotide that results in early stop codon usually deleterious
  57. frameshift
    addition or deletion of a nucleotide usually deleterious
  58. template strand
    strand that is read by the enzyme, RNA polymerase
  59. Nontemplate, coding strand
    its sequence matches the sequence of the RNA that is transcribed from the template strand and codes for a polypeptide
  60. RNA has Uracil rather than thymine
  61. RNA polymerase 1
    genes that code for most of the large RNA molecules (rRNA) found in ribosomes)
  62. RNA polymerase II
    protein coding genes (produce mRNA) genes that code for RNAs that function in ribosome assembly, and in processing and regulation of mRNAs
  63. RNA polymerase III
    genes that code for transfer RNAs(tRNAS) for pme pf the s,a;; rRMAs found in robosomes and for noncoding RNAs (ncRNAs), also genes that code for RNAs that function in ribosome assembly and in processing and regulation of mRNAs
  64. structure and function of RNA polymerase
    bacterial RNA polymerase is a large globular enzyme with several channels
  65. Before transcription can begin ______
    a detachable protein subunit called sigma must bind to polymerase
  66. holoenzyme
    formed by bacterial RNA polymerase and sigma. consists of a coreenzyme (contains active site for catalysis and other required proteins)
  67. holoenzyme binds tightly to specific sections of DNA called
    promoters
  68. TATA boc
    centered about 30 base pairs upstream of the transcription start site, many of eukaryotic promotors have
  69. ___ makes the initial contact with DNA that starts transcription
    SIgma, not RNA polymerase (supports hypothesis that sigma is a regulatory protein)
  70. each type of sigma protein allows RNA polymerase to
    bind to a different type of promoter and therefore a different kind of gene
  71. basal transcription factors
    initiate eukaryotic transcription by binding to the appropriate promoter region in DNA. assembles st promoter first, the RNA polymerase
  72. Once sigma binds to a promoter for a bacterial gene
    DNA helix opens. beginning transcription
  73. elongation
    RNA polymerase moves along the DNA template in the 3' -> 5' direction but synthesizes RNA in the 5' -> 3' direction
  74. transcription ends with
    termination phase, RNA polymerase encounters a transcription termination signal that causes the RNA to form a hairpin structure
  75. In bacteria, information in DNA is converted to mRNA
    directly, in eukaryotes it isn't
  76. when a eukaryotic gene is transcribed, the product is an immature primary transcript, pre-MRNA.
  77. exons
    region of eukaryotic gene that is translated into a peptide or protein
  78. intron
    region of eukaryotic gene that is transcribed into RNA but is later removed, so it is not translated into a peptide or protein
  79. introns are removed from growing RNA strand by process known as
    splicing
  80. small nuclear ribonucleoproteins (snRNPs)
    protein-plus-RNA complexes
  81. splicing process
    snRNPs bing to 5' exon-intron boundary, more arrive to form complex called spliceosome. The intron forms a loop with the key adenine at its connecting point, and then the loop is cut out and a phosphodiester bond links the eons on either side, producing a contiguous coding sequence.
  82. after intron splicing is complete, enzymes add a
    structure called the 5' cap.
  83. An enzyme cleaves the 3' end of most RNAs ode transcription is complete and another enzyme adds a long row of adenine nucleotides called
    poly(A) tail
  84. with the addition of the cap and tail and completion of splicing,
    processing of the primary RNA transcript is complete and the product is a mature mRNA
  85. where does translation occur
    ribosomes
  86. in bacteria, transcription and translation can occur
    concurrently because there is no nuclear envelope to separate the two processes, physically connected
  87. in eukaryotes, transcription and translation
    separate, transcripts are processed to produe mature mRNA, which can be used to begin translation. separate in time and space
  88. RNA polymerase transcription
    bacteria: 1 eukaryotes: 3, each different RNA
  89. promotor structure transcription
    • bacteria: typically contains a -35 box and a -10 box
    • Eukaryotes complex and variable, TATA box
  90. proteins involved in contacting promoter transcription
    • bacteria: sigma, different versions bind to different promoters
    • Eukaryotes many basal transcription factions
  91. RNA processing transcription
    • bacteria: none
    • eukaryotes: extensive, cap splicing and addition of tail
  92. tRNA
    picks up specific amino acid and binds to the corresponding codon in messenger RNA during translation
  93. how tRNA gets amino acids
    • input of energy (ATP) required to attach amino acid to tRNA
    • enzymes called aminoacyl tRNA syntheses catalyze addition of amino acids to tRNAs, for each of 20 amino acids, different aminoacyl tRNA synthetase and one or more tRNAs
  94. aminoacyl tRNA
    combination of a tRNA molecule covalently linked to an amino acids.
  95. tRNA structure
    a CCA sequence at 3' end of molecule offers binding site for amino acids, while codon at loop at far end serve as anticodon ( set of three ribonucleotides that form base pairs with mRNA codon)
  96. ribosomes contain
    protein and ribosomal RNA (rRNA)
  97. Large subunit of ribosome
    where peptide-bond formation takes place
  98. small subunit of ribosome
    holds mRNA in place during translation
  99. during translation, tRNAS found at
    three sites in ribosomes
  100. tRNAs are bound at their
    anticodons to corresponding mRNA codon
  101. A site of ribosome
    acceptor site for an aminoacyl tRNA
  102. p Site of ribosome
    where peptide bond forms that adds an amino acid to the growing polypeptide chain
  103. E site
    where tRNAS no longer bound to an amino acid exit the ribosome
  104. three step sequence of protein synthesize of ribosome
    • 1. aminoacyl tRNA diffuses into A site, anticodon binds to a codon in mRNA
    • 2. peptide bond forms between the amino acid held by the aminoacyl tRNA in the A site and the growing polypeptide, which was held by a tRNA in the p site
    • 3. The ribosome moves ahead, three tRNAs move one position down line. tTRNA in e site exits, tRNA in p site moves to E, and tRNA in A site switches to P site.
  105. initiation in bacteria of translation
    mRNA binds to small ribosomal subunit, initiator aminoacy tRNA bearing f-met binds to start codon, and large ribosomal subunit binds, completing the complex.
  106. at start of elongation phase, initiator tRNA is in
    P site, e and a site empty
  107. elongation process
    initiator tRNA binds to P site, aminoacyl tRNA binds to the codon in the A site via complementary base pairing between anticodon and codon, and peptide bond formation occurs between amino acids on the tRNAs in the P and A sites
  108. When both the P site and A site are occupied by tRNAs,
    the amino acids on the tRNAs are in the ribosome's active site. This is where peptide bond formation, the essence of protein synthesis, occurs
  109. protein synthesis is catalyzed by
    RNA, ribosome is a ribozyme, not an enzyme
  110. translocation
    moves empty tRNA into E site, moves tRNA containing the growing polypeptide into P site, and opens A site and exposes new mRNA codon. \
  111. Termination
    starts when A site encounters stop codon, causing protein called release factor to enter site (resembles tRNA in size and shape but does not have amino acid), which catalyze hydrolysis of bond linking tRNA in P site with polypeptide chain

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