Gene Expression 3 - Chapter Three.txt

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Gene Expression 3 - Chapter Three.txt
2013-01-22 21:13:12
Biology Gene Expression Tony Russell Genetics

Gene Expression
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  1. What is the Mendelian definition of a Gene?
    A unit of Heredity that controls a phenotypic trait.
  2. What is the Molecular definition of a Gene?
    A portion of a chromosome that is Transcribed into DNA, including all regulatory regions associated with it.
  3. A promoter region is...
    A) a region marking the start of RNA transcription (RNA polymerase binding site).
    B) a small piece of RNA used to initiate replication.
    C) a region marking the start of DNA replication (DNA polymerase binding site).
    A) a region marking the start of RNA transcription (RNA polymerase binding site).
    (this multiple choice question has been scrambled)
  4. What is a Genome.
    The full set of genetic information an organism contains.
  5. A gene mutation on one section of DNA directly causes a wrong amino acid to be chosen, and a dysfunctional protein as a result. What sort of gene was affected?
    A protein coding gene.
  6. A gene mutation stops translation of a specific amino acid in a cell because there is nothing to transport it. What sort of gene is affected?
    A non-coding gene.
  7. Are mRNA's of fRNA's more stable?
    fRNA's are as mRNA's are only temporary.
  8. What is the direction of RNA synthesis? What does this mean about the directionality of of the polymerase along the coding strand?
    RNA is always synthesized in the 5' to 3' position. As a result, the polymerase reads the DNA in the 3' to 5' direction.
  9. What is the directionality of a Ribosome?
    5' to 3'
  10. A disease is the result of the following mutation,
    -GAG- becomes -GUG-
    What is this disease? What effect does this mutation have on the amino acid sequence (see amino acid chart).
    • The disease is sickle cell anaemia, whereby the mutation affects beta-globin.
    • In this mutation, the amino acid Glutamate is replaced with Valine.
  11. What is a silent mutation?
    A mutation which has no effect on phenotype.
  12. What is a conservative mutation?
    A mutation which results I'm substitution of none amino acid with another similar one. The result is a very small effect on observable phenotype.
  13. Where in a protein might a hydrophobic Amino Acid be found?
    Towards the centre, as a result of its hydrophobicity.
  14. Where in a protein might a hydrophillic amino acid be found?
    Towards the exterior.
  15. Some Amino Acids act directly with the phosphodiester backbone. What properties might these Amino Acids have?
    A charge (+ or -) so as to interact with the O- on the phosphate.
  16. On the diagram,

    Which Strand is the Template Strand?
    Which Strand is the Coding Strand?
    Which Stand is the Non-Template Strand?
    • Strand A is the Template Strand.
    • Strand B is the Non-Template Strand
    • Strand B is the Coding Strand.
  17. Describe the structure of a Beta Pleated Sheet.
    Beta Pleated Sheets consist of chains of amino acids (Polypeptides) in the same plane, held in Beta Sheet conformation by Hydrogen Bonds.
  18. In what level of Protein Structure do "Turns" occur?
    Secondary Structure.
  19. In what two ways are proteins diagrammed?
    Ball and Stick and Ribbon.
  20. What is a Motif with respect to Domains in Proteins?
    • A Motif is a consistent structural unit with a specific function.
    • E.g "Zinc Finger".
  21. Is Primary Structure the only factor responsible for Protein Folding?
    No. Many proteins do not fold correctly on their own (as would be the case if Primary Structure was the deciding factor).
  22. Describe what is happening in this picture of Initiation of Transcription
    • RNA polymerase has bound to the promotor on the template strand, melting at least 12 bases.
    • The RNA has Placed a purine base, followed by another base to complete the first Phosphodiester bond.
  23. Describe what is happening in the picture of Elongation of Translation.

    In What direction is the DNA being read?
    • The RNA polymerase has moved out of the promotor region.
    • The RNA polymerase is moving along the DNA in the 3' to 5' direction.
    • As the RNA polymerase is moving along the DNA, a Transcription bubble is forming ahead of it and closing behind it.
  24. Briefly summarize Termination of Transcription.
    Termination occurs when a Terminator aids in loosening and detaching of the mRNA and DNA causing the RNA polymerase to detach.
  25. Generally, what are the first bases to be "laid down" at the promotor region?
    Purines (Adenine and Guanine)
  26. What holds the mRNA backbone together?
    Phosphodiester bonds, like those in DNA.
  27. During Initiation of Transcription, how many bases does RNA Polymerase expose?
    Twelve or more.
  28. What is one difference between transcription and Translation?
    • Transcription forms a replication bubble.
    • DNA replication makes two products using each strand. Transcription makes only one.
  29. Transcription is Asymmetrical. What does this mean?
    Only one specific strand is copied.
  30. Briefly explain Sedimentation Coefficients.
    • The sedimentation coefficient of a molecule is how fast it migrates in an ultracentrifuge.
    • Heavy and/or spherical particles have higher sedimentation coefficients.
  31. Escherachia Coli ribosomes have to subunits. What are their sedimentation coefficients.
    • Small Subunit - 30S
    • Large Subunit - 50S
    •      Total         - 70S (Not 80)
  32. What is tRNAMet?
    Transfer RNA  with an anticodon anacceptor stem specific to Methionine.
  33. How does a tRNA become charged?
    tRNA is charged when one of a group of enzymes known as Aminoacyl-tRNA-synthases attach a specific Amino Acid to the Acceptor Stem.
  34. Why is the genetic code described as Degenerate?
    Because multiple codons often code for single Amino Acids.
  35. what is the sequence of the "Start" codon in Translation? What does it code for?
    5'-AUG-3' This codes for Methionine.
  36. If eukaryotes use Methionyl-tRNA in initiation of elongation, what do Bacteria use?
    Bacteria use N-Methionyl-tRNA (Methionyl-tRNA with a formyl group attached to the amino end of Methionine).
  37. Does the where might an 5'-AUG-3' codon be found on mRNA, with respect to translation?
    The AUG codon is found both at the beginning of a protein coding sequence, or elsewhere in the mRNA.
  38. When discussing codons in Translation, are we talking about DNA or RNA?
    mRNA is translated, whereas DNA never is. Therefore we are discussing RNA.
  39. What is a Shine-Delgarno Sequence? In what kind of organism would you find one?
    • Shine-Delgarno Sequences are used to attract Ribosomes to initiate Translation.
    • They are found in Bacteria (Never Eukaryotes).
  40. Shine-Delgarno Sequences are found in         whereas eIF4e is found in            .

    A) Bacteria, Eukaryotes.
    B) Bacteria, Archaea
    C) Eukaryotes, Archaea
    D) Eukaryotes, Bacteria.
    A) Bacteria, Eukaryotes.
    (this multiple choice question has been scrambled)
  41. What is eIF4E?
    eIF4E is a protein that binds to the 5' cap of eukaryote mRNA and stimulates attraction of ribosomes.