Bio Lecture Ch 14

  1. Neurospora crassa is?
    • a common bread mold/fungus
    • haploid alleles
    • minimal nutrients needed
    • used for mutation expirement
  2. Mutagen
    something taht causes mutations
  3. Mutation
    inherited genotypic changes
  4. One-gene, One-enzyme hypothesis
    genes are related directly with enzymes
  5. one-gene, one-polypeptide relationship
    a gene and a polypeptide are closely related
  6. Steps for going from DNA to protein (the central dogma of molecular biology)
    • transcription - info in DNA is copied onto a complimentary RNA sequence
    • Translation - the RNA sequence is used to create that amino acid sequence of a polypeptide
  7. RNA's differences to DNA
    • RNA usually only has one polynucleotide strand
    • sugar molecule in RNA is ribose
    • Has uracil (U) instead of Thymine (T)
    • -so A=U as C=G
  8. 3 Types of RNA and Functions of each
    • Messenger RNA (mRNA) - carries a copy of a gene sequence in DNA to a ribosome
    • Transfer RNA (tRNA) - carries amino acids to the ribosome for assembly into polypeptides
    • Ribosomal RNA (rRNA) - catalyzes peptide bond formation and provides frame work for ribosome
  9. Codons
    • 3 consecutive nucleotides
    • informational sequence
    • different codons encode different amino acids
  10. transcript
    the mRNA copy of a gene
  11. reverse transcription
    synthesis of DNA from RNA
  12. Componants of transforming RNA to DNA
    • DNA template for base pairing
    • the appropriate substrates
    • an RNA polymerase enzyme
  13. RNA polylerase
    catalyze the synthesis of RNA from the DNA template
  14. Transcription steps
    • Initiation - promoter a sequence of DNA (AUG) that binds with RNA polymerase
    • Elongation - RNA polymerase unwinds the DNA about 10 base pairs at a time and reads it 3' to 5'
    • Termination - ends process
  15. genetic code
    specifies whis amino acids will be used to build a protein
  16. Start codons
    AUG - initiates the signal for translation
  17. stop codons
    UAG/UAA/UGA - terminate signals for translation
  18. terminator
    signals the end of transcription
  19. introns
    INtervening RegiONS - noncoding base sequences
  20. Exons
    EXpressed regiONS - coding sequences
  21. Both introns and exons make
    primary mRNA transcript (Pre-mRNA)
  22. Nucleic acid hybridization
    • method for locating introns
    • 1- target DNA is denatured
    • 2- probe incubated with denatured DNA
  23. Probe
    a single-stranded nucleic acid from another source
  24. domains
    different functional regions of a protein
  25. G cap
    • added to 5' end of Pre-mRNA as transcribed
    • molecule of GTP
    • helps bind mRNA to ribosomes for translation
    • protects mRNA from being digested by ribonucleases
  26. Poly A tail
    • added at 3' end of pre-mRNA at the end of transcrition
    • acts as a signal for an enzyme to cut the pre-mRNA
    • assists in export of mRNA from nucleus
    • helps with mRNA stability
  27. RNA Splicing
    process that removes introns and splices the exons together
  28. small nuclear ribonucleoprotein particals
    binds the the ends of exons near the splice sites
  29. spliceosome
    • RNA protein complex formed by protiens added using ATP
    • cuts pre-mRNA, releases the introns, and rejoinds at exons to produce mature mRNA
  30. tRNA functions
    • bind to a praticular amino acid (charged)
    • associates with mRNA
    • interacts with ribosomes
  31. ribosome
    • "work bench" of translation
    • holds mRNA and tRNA in position for polypeptide assembly
  32. ribosome's 2 subunits
    • Large - contains A (amino acid) site, P (polypeptide) site, and E (exit) site
    • small - binds to sequence on mRNA
  33. polyribosomes/polysomes
    combination of mRNA strand, ribosomes, and polypeptides
  34. signal sequence
    indicates where in the cell the polypeptides belong
  35. docking protein
    • a specific receptor protein that a signal sequence binds to
    • on the outer membrane of an organelle (nucleus/mitochondrion/chloroplast)
  36. signal recognition particle
    • a particle composed of protein and RNA that the signal sequence binds to
    • in ER
  37. modifications after translation
    • proteolysis
    • glycosylation
    • phosphorylation
  38. proteolysis
    cutting of the peptide chain to allow fragments to fold into different shapes
  39. glycosylation
    adding sugars to improve targeting and recognition
  40. phosphorylation
    add phosphate groups to alter the shape of the protein
Card Set
Bio Lecture Ch 14
Che 14 "From DNA to Protein: Gene Expression"