bio 121

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Author:
clw3534
ID:
9720
Filename:
bio 121
Updated:
2010-03-09 02:11:40
Tags:
Chapter 10
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Description:
Gene Expression and Regulation
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  1. Genes are the ___
    Proteins are the ___
    genes are the blueprint, they provide info to make proteins

    Proteins are the cell's "molecular workers"
  2. DNA provides instructions for protein synthesis via
    RNA intermediates
  3. Structural differences between DNA and RNA:
    • RNA : base (U) uracil.
    • Single stranded
    • 3 types

    • DNA: (T)
    • double stranded.

    Function: contains genes; sequence of bases in most genes deternmines the amino acid sequence of a protein.
  4. WHat are the 3 kinds of RNA?
    • mRNA: messenger
    • tRNA: transfer: binding sites. amino acids.
    • rRNA: ribosomal
  5. Processes involved in the use and inheritance of genetic info. Next 3 cards

    Transcription:
    • synthesis of RNA.
    • Short segment of one DNA strand.
    • Product is one RNA molecule.
    • Enzyme used is RNA polymerase.
    • Base pairing is DNA with RNA.
  6. Translation
    • synthesis of protein.
    • Info for process is mRNA.
    • Product is one protein molecule.
    • major enzyme used is ribosome. (also requires tRNA)
    • Base pairing: mRNA with tRNA. Codon forms pair with anticodon
  7. Replication
    • synthesis of DNA; occurs only before cells divide.
    • Info for process: entire length of both DNA strands.
    • Product: 2 DNA double helices (each with one old and one new strand)
    • Enzyme used: DNA polymerase
    • Base pairing: DNA with DNA
  8. How is information in a gene transcribed into RNA?
    Initiation- RNA polymerase

    Elongation

    Termination
  9. Initiation-
    RNA polymerase binds at the promoter region (TATA) and the DNA unwinds. THe promoter is an important site of gene regulation.

    BINDS
  10. Elongation:
    RNA polymerase travels down one of the DNA strands (the TEMPLATE strand), synthesizing RNA. Base-pairing rules stil apply, and so a single RNA strand complementary to the template strand is made. DNA rewinds after polymerase passes.
  11. Termination:
    termination signal: sequence of bases in the template strand which causes RNA polymerase to release the completed RNA strand and then detach itself from the DNA.
  12. mRNA
    carries information from the nucleus to the cytoplasm: it codes for the amino acid sequence of the protein to be synthesized. MESSENGER
  13. rRNA:
    an integral part of the structure of ribosomes. Ribosomes consists of two parts, the large ribosomal subunit and the small ribosomal subunit.
  14. tRNA:
    decodes the sequence of bases on mRNA. Each tRNA carries the anticodons which matches the codon on the mRNA, and has the specific amino acid that matches the codon attached to it.
  15. Protein Synthesis:
    Initiation: tRNA and mRNA bind to a ribosome. The initation codon, AUG: tells the ribosome where to start. It has 2 binding sites and hold two tRNAs during the translation.

    Elongation: protein synthesis. Another tRNA binds to the second binding site and a peptide bond forms. The complex moves one codon along the mRNA and the process is repeated.

    Termination: translation ends. WHen a stop codon reached, special proteins bind and the ribosome releases the completed protein.
  16. Mutation
    any change in DNA sequence of a gene
  17. Mutations form by:
    faulty base pairing during replication of DNA

    spontaneous chemical changes

    mutagen, either chemical or radiation.
  18. What are the three main types of mutations and the consequences.
    point mutations

    insertions and deletions: result in a frame-shift which is usually catastrophic. The resulting protein is non-functional

    • Nucleotide substitutions may have:
    • no change in protein
    • amino acid changed, but no effect on protein: neutral mutation.
    • protein function is changed or destroyed.
  19. Gene expression:
    express genes needed for cell type. Only those proteins necessary for a specific cell type are produced.

    Expression can change over time

    Environment can regulate expression.
  20. Regulation can occur at several steps during expression.
    • Transcription
    • Translation
    • Post-translation modification of proteins
    • life span of proteins.
  21. Androgen insensitivity:
    genetically XY but lacking funcational testosterone receptors.

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