CH. 17 STUDY GUIDE: PROTEIN SYNTHESIS
Transcription and Translation
KEY TERMS
protein synthesis
termination
DNA
termination codon
RNA
nonsense codes
messenger RNA (mRNA)
initiation(=start) codon
RNA polymerase
termination(=stop) codon
promoters
anticodon
terminators
sense strand
codon
non-sense strand
transfer RNA (tRNA)
introns
anticodon
exons
ribosomal RNA (rRNA)
RNA splicing(=RNA processing)
ribosome
mutation
subunits
base-pair substitution
initiation
insertion
initiation factors
deletion
reading frame
frameshift
elongation
mutagen
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WORD ROOTS
anti - = opposite (anticodon: a specialized base triplet on one end of tRNA molecule that
recognizes a particular complementary codon on an mRNA molecule)
exo - = out, outside, without (exon: a coding region of a eukaryotic gene that is expressed).
intro - = within (intron: a noncoding, intervening sequence within a eukaryotic gene).
muta - = change; - gen = producing (mutagen: a physical or chemical agent that causes
mutations).
poly - = many (poly(A) tail: the modified end of the 3’ end of an mRNA molecule consisting of the
addition of some 50 to 250 adenine nucleotides)
trans - = across; - script = write (transcription: the synthesis of RNA on a DNA template).
QUESTIONS
1. Describe Beadle and Tatum's one gene-one enzyme hypothesis. How did
these guys come up with this one? How is this hypothesis stated today?
2. State three ways in which RNA differs from DNA. Name three types of
RNA and give the function of each type. Describe the process of
translation; describe initiation, elongation and termination and show how
the sequence of bases in DNA determines the amino acid sequence in the
protein.
3. Describe the process of translation; describe initiation, elongation, and
termination and show how the sequence of the basis in DNA determines
the amino acid sequence in the protein.
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4. Be sure that if you are given the genetic code table, you can give the
amino acid sequence for any given mRNA.
5. In a hypothetical strand of DNA the base sequence is:
(3')-AAGTTTGGTTACTTC-(5')
o
What is the mRNA sequence transcribed from this DNA?
o
What is the amino acid sequence translated from this mRNA?
o
Does it matter in which direction the transcription occurs? Why?
6. Sketch a typical tRNA molecule, indicating the location of the anticodon
and the position at which the amino acid becomes attached.
7. Describe in some detail how the genetic code is read by the ribosome. In
doing so explain the terms codon, anticodon initiation(start) codon and
termination(stop) codon.
8. Define mutation, give examples and indicate how mutations can be
induced.
9. What agents can cause mutations?
10. What is the significance of having 64 codons in the genetic code? What is
the value, if any, in the redundancy in the code?
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