Essay About Portion Of A Specific Dna Molecule And Initiation Factors

Nucleotide Triplets:
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NA QUESTION 1982:
L. PETERSON/AP BIOLOGY
A portion of a specific DNA molecule consists of the following sequence of
nucleotide triplets:
TAC GAA CTT CGG TCC
This DNA sequence codes for the following short polypeptide:
methionine – leucine – glutamic acid – proline – arginine
Describe the steps in the synthesis of this polypeptide. What would be the
effect of a deleltion or an addition in one of the DNA nucleotides? What would
be the effect of a substitution in one of the nucleotides?
STANDARDS:
In the transcription phase of protein synthesis, students were given a point for a correct
definition of transcription. They were awarded one point for mentioning each of the following:
__ DNA as the template molecule for messenger RNA
__ The proper base pairing (including the uracil substitution)
__ The chemical characteristics of nucleotides
__ A comparison of RNA and DNA (other than uracil substitution)
__ The triplet arrangement of codons and/or anticodons
__ The control of transcription (Operon, etc.)
__ Promoters
__ The role of polymerase
__ Intervening sequences in eukaryotic cells
__ Factors involved in the release of mRNA from DNA
__ 5 – 3 arrangement with attachment at -OH end
A definition of translation was worth an additional point with one point given for
mention of each of the following:
__ Movement of mRNA from nucleus to ribosome
__ Association of mRNA with the ribosome and ribosomal RNA
__ Location of ribosomes
__ Description of ribosome/polyribosome structure
__ Role of transfer RNA in transporting amino acids
__ Specific characteristics of tRNA
__ Amino acid-tRNA complex activation
__ Role of ATP and enzymes
__ tRNA initiator molecules (met or f-met)
__ Initiation factors (GTP, etc.) resulting in union of 30s and 50s
__ Bonding of tRNA to 50s (A site)
__ Role of amino transferase
__ Initiation codons