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Flashcards

DNA

Maya Bird MCAT MCAT Inglês 88 flashcards

Flashcards do conjunto (88)

  1. 1What is mRNA?messenger RNA, a single strand of RNA transcribed from DNA, translated into protein
  2. 2What are the differences between DNA and RNA?deoxyribose sugar vs ribose sugar
    thymines vs uracil
  3. 3What enzyme is primarily responsible for transcription?RNA polymerase II
  4. 4What does RNA polymerase II do?Uses a strand of DNA as a template to make a complementary RNA strand (mRNA transcript)
  5. 5What is pre-mRNA?The unprocessed mRNA transcript
    (eukaryotic cells)
  6. 6How is pre-mRNA processed into mature mRNA?Protection - 5' G cap and poly-A tail
    Splicing - removal of introns
  7. 7What is the 5' G cap?A modified G nucleotide on the 5' end of mRNA
  8. 8What is the poly-A tail?A sequence of A nucleotides (~250) on the 3' end of mRNA
  9. 9Why does mRNA need to be protected?When it travels to the cytoplasm, exonucleases can target and degrade mRNA
  10. 10Why does mRNA need to be spliced?To save space, time, energy
  11. 11What is a spliceosome?Enzyme that cuts out introns and fuses ends of exons together during splicing step
  12. 12What is siRNA?Short interfering RNA
    (can capture and destroy viral mRNA before they get to ribosomes)
  13. 13What is the DNA backbone composed of?sugar (deoxyribose) and phosphate (acid)
  14. 14What are the DNA "rungs" composed of?Pairs of nitrogenous bases (adenine, guanine, cytosine, thymine)
  15. 15What components make up a nucleotide?1) Phosphate group
    2) Sugar
    3) Nitrogenous base
  16. 16What is a purine and which ones are they?Nitrogenous base with 2 rings
    Adenine and Guanine
  17. 17What is a pyrimidine and which ones are they?Nitrogenous base with 1 ring
    Cytosine and Thymine
  18. 18Why do we say DNA strands are anti-parallel?They run anti-parallel - one backbone runs 5' to 3' and the other runs 3' to 5'
  19. 19What type of bond holds the DNA backbone together?Phosphodiester linkages (covalent) between sugar and phosphate groups
  20. 20What type of bond hold the DNA base pairs together?Hydrogen bonds between bases (N)
  21. 21What is a chromosome?A structure of protein and DNA
  22. 22What is a telomere?Noncoding genes on ends of chromosomes
  23. 23What do telomeres do?Protect ends of chromosomes from deterioration during replication ("buffer zone")
    Prevent chromosomes from sticking together
  24. 24What is telomerase?Enzyme that lengthens telomeres (allowing for more replication)
  25. 25What happens when telomeres run out?Chromosomes can't replicate
  26. 26What is the difference between single copy DNA and highly repetitive DNA in terms of genetic info?single copy - holds important genetic info
    highly repetitive - hold no genes
  27. 27What is the difference between single copy DNA and highly repetitive DNA in terms of transcription/translation?single copy - transcribed and translated
    highly repetitive - neither transcribed nor translated
  28. 28What is the difference between single copy DNA and highly repetitive DNA in terms of mutation rate?single copy - low mutation rate
    highly repetitive - very high mutation rate
  29. 29Where is somewhat repetitive DNA found?Near centromeres
  30. 30In what direction can DNA polymerase extend DNA?5' -> 3'
  31. 31What is topoisomerase?Enzyme that unwinds the DNA double helix
  32. 32What is helicase?Enzyme that breaks hydrogen bonds between bases
  33. 33What is the leading strand?Strand where DNA polymerase moves in 5' -> 3' direction (fast)
  34. 34What is the lagging strand?Strand where DNA polymerase moves in 3' -> 5' direction (slow)
  35. 35What is DNA primase?Enzyme that places RNA primer so DNA polymerase can elongate them with DNA
  36. 36What is DNA polymerase?Enzyme that adds the correct nucleotides to the sequence
  37. 37What is DNA ligase?Enzyme that can join single strand DNA fragments
  38. 38What are Okazaki fragments?Fragments of DNA created on the lagging strand that are not yet connected
  39. 39What is the difference between transcription in eukaryotic and prokaryotic cells?Eukaryotic - requires processing
    Prokaryotic - doesn't require processing (no nucleus)
  40. 40How does RNA polymerase work?Attaches to recognition sites and promoter region of DNA, separates strands and codes RNA strand that is complementary to one DNA strand
  41. 41In what direction can RNA polymerase code RNA?5' -> 3'
  42. 42What is the template strand?The DNA strand RNA polymerase uses to create complementary RNA
  43. 43What is the coding strand?The DNA strand not used to create RNA, matches the resulting RNA (aside from T and U)
  44. 44When does RNA polymerase stop?When it reaches the terminator region
  45. 45What is mature mRNA?The processed RNA with protection and only exons
  46. 46What is a ribosome?An organelle made of proteins and ribosomal RNA that reads mRNA and creates an amino acid sequence
  47. 47What is a codon?A sequence of 3 nucleotides that code for an amino acid
  48. 48What is the start codon sequence?AUG
  49. 49What are the stop codon sequences?UAA
    UAG
    UGA
  50. 50What is the relationship betwen number of codons and number of amino acids?There are more possible codons than possible amino acids, and more than one codon can code for the same amino acid
  51. 51What is tRNA?transfer RNA, have anticodons (pair with codons) and a corresponding amino acid
  52. 52What are the 3 sites of a ribosome and why are they named as such?A site - where tRNA is holding amino acid
    P site - where tRNA is holding polypeptide chain
    E site - where tRNA exits ribosome
  53. 53What are the 3 steps of translation?1) tRNA holding amino acid binds to A site
    2) peptide bond forms between amino acids, creating polypeptide chain at P site
    3) tRNA exits at E site
  54. 54What subunits are found in prokaryotic cell ribosomes?50S and 30S
  55. 55What subunits are found in eukaryotic cell ribosomes?60S and 40S
  56. 56What is the Shine-Delgarno sequence?Sequence on prokaryotic mRNA where ribosome binds
  57. 57Where does the ribosome bind on eukaryotic mRNA?the 5' cap
  58. 58What are the differences between eukaryotic and prokaryotic mRNA sequences?eukaryotic - has 5' cap and poly-A tail
    prokaryotic - has Shine Delgarno sequence
  59. 59What are the differences between eukaryotic and prokaryotic start codons?prokaryotic - formyl-methionine amino acid
    eukaryotic - methionine amino acid
    (allows for differentiation)
  60. 60What doe DNA polymerase III do?Fixes mistakes during DNA replication
  61. 61What is an exonuclease?Enzyme that removes nucleotides from ends of DNA strand
  62. 62What is an endonuclease?Enzyme that removes nucleotides from middle of DNA strand
  63. 63What does DNA polymerase I do?Removes RNA primer at end of DNA replication
  64. 64What are the 4 steps of the mismatch repair mechanism?1) mistake is identified and marked with a cut
    2) exonuclease removes nucleotide
    3) DNA polymerase places correct nucleotide
    4) DNA ligase joins nucleotide to neighbors and its pair
  65. 65What can UV rays cause in DNA?Formation of pyrimidine (T or C) dimers, misshaping backbone
  66. 66What is endogenous DNA damage?Damage caused by something inside the body
  67. 67What is exogenous DNA damage?Damage caused by something outside the body
  68. 68What are the steps of nucleotide excision repair?1) endonuclease cuts out incorrect nucleotides/dimer
    2) DNA polymerase brings correct nucleotides
    3) DNA ligase joins nucleotides to neighbors and pair
  69. 69What is senescence?When a cell is in a dormant state where it does not divide
  70. 70What is apoptosis?Programmed cell death
  71. 71What is cancer?Unregulated cell division and growth
  72. 72What is semi-conservative replication?The parent DNA creates two pairs of DNA strands each pair with one strand of the parent's original DNA
  73. 73What are the two groups of protein modifications?co-translational
    post-translational
  74. 74Where do co-translational protein modifications occur?Near the ribosome (as it's being translated)
  75. 75Where do post-translational protein modifications occur?in ER or Golgi Apparatus
  76. 76What is an example of a co-translational protein modification?acetylation
  77. 77What are 6 types of post-translational modifications?1) glycosylation
    2) lipidation
    3) phosphorylation
    4) methylation
    5) proteolysis
    6) ubiquitination
  78. 78What is glycosylation?The addition of a carbohydrate to a protein
  79. 79What is lipidation?The addition of a lipid/fat to a protein
  80. 80What is phosphorylation?The addition of a phosphate group to a protein
  81. 81What is methylation?The addition of methyl groups to a protein
  82. 82What is proteolysis?The cutting of a protein
  83. 83What is ubiquitination?The addition of ubiquitin to a protein (marks for degradation)
  84. 84Why is gene expression regulated at the transcription level?This saves space and energy, it is most efficient!
  85. 85What reaction is used to create phosphodiester linkages in DNA?dehydration synthesis
  86. 86What is a hydrogen bond?Weak bond between H (positive, donor) and electronegative atom N, O (negative, acceptor)
  87. 87How do nitrogenous bases differ in their hydrogen bonding?Adenine and thymine have 1 hydrogen bond donor and 1 acceptor (match)
    Cytosine has 1 donor and 2 acceptors
    Thymine has 2 donors and 1 acceptor
  88. 88What is junk DNA?sequences of non-gene nucleotides found in DNA

Informações

Descrição
1 - Biomolecules
Criado por
Maya Bird · nov 2022
Atualizado
23 nov 2022
Visualizações
2
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