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nakinian123 nakinian123
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8 years ago
Cancer often involves excessive and uncontrolled mitosis, resulting in a tumour. Some of the chemotherapeutic agents used in cancer therapy inhibit DNA replication. Propose and explain two possible ways that chemotherapy drugs can inhibit replication.  While this is sometimes successful in stopping tumour growth, there are side effects. What do you think these side effects might be?

Given the following codons and their corresponding amino acids (T & I /10)

     UUU- Pheylalanine
     CUA – Leucine
     GCU – Alanine
     AAA – Lysine

 a)  show the mRNA which codes for the short peptide, lys-ala-phe-leu.  Include what should come before and after this short message. (2 )

 b)    Show the tRNAs that would line up at the mRNA and their anticodons (2)


 c)  Show the base sequence that would be found in the DNA double helix which carries the gene for this peptide.  Label the coding and template strand.

 d)    What if there was a frameshift at leucine.  A cytosine was inserted directly after the first cytosine (on the template strand).  How would the amino acid sequence be altered?  Would this alter translation?

 e)  When the DNA was replicated which enzymes were responsible for this error?
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wrote...
8 years ago
A) mRNA: AAA GCU UUU CUA

A start codon comes before the sequence which will code for methionine. A stop codon will come after the sequence which causes the disassembly of the ribosome.

B) tRNA: UUU (lys) CGA (ala) AAA (phe) GAU (leu)

The above mRNA sequence undergoes translation with the appropriate tRNA; which has the complementary base pair, using uracil (U) - not thymine (T) to pair with adenine (A), as the anticodon.

C) DNA:
coding: TTT CGA AAA GAT
template: AAA GCT TTT CTA

Uses T, not U, to pair with A. The coding strand will undergo transcription to give the above mRNA sequence.

D) You don't make any mention of cytosine anywhere in the above sequences. However a frameshift mutation will alter translation by the addition or removal of an entire amino acid (1 codon or 3 base pairs). A frameshift mutation will not effect the amino acids before or after the site where the mutation has occurred.

E) DNA Polymerase is the enzyme that replicates DNA and would be the enzyme responsible for the error because DNA poly. has its own correction mechanism, like a spell check type of thing.
Biology - The only science where multiplication and division mean the same thing.
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