Download Translation and Mutations Practice

Translation and Mutations Practice
ANSWERS
1) Below is a strand of mRNA. The underlined segments represent introns, and those not
underlined represent exons. What will be the final strand of mRNA (write the final strand on
the space provided below, making sure each codon fits between the dotted lines)? The first one
has been done for you.
UUACGUAUGGUGAGUACCCGAGGUAACUCGGGAUUGUGA
mRNA codons:
UUU
AUG
UAC
CCG
AGG
UGG
GAU
UGA
tRNA anticodons: AAA
UAC
AUG
GGC
UCC
ACC
CUA
ACU
Amino Acids:
Met.
Tyr.
Pro.
Arg.
Asp.
Stop
Codon
Phen.
a) How many codons does the finished mRNA represent?
Try.
8
2) Using the space above, fill in the missing tRNA anticodons.
3) Using the space above, fill in the missing amino acids. *remember that translation begins with
a certain start codon.
a) How many amino acids long is your finished polypeptide?
6
Section 8.7 (Mutations)
Answers to questions 1-3 on page 255:
1. Explain why frameshift mutations have a greater effect than do point mutations?
Frameshift mutations are more severe than point mutations because point mutations
only change a single codon (1 amino acid change), where frameshift mutations can
affect the ENTIRE sequence after the mutation (many amino acid changes).
2. If GUA is changed to GUU, will the resulting protein be affected? Explain.
If GUA were changed to GUU, the resulting protein WOULD NOT be affected. This is
because both GUA and GUU code for the same amino acid. This is called a SILENT
(point) mutation.
3. Explain how mutagens can cause genetic mutations in spite of your body’s DNA repair
enzymes?
Sometimes mutagens cause so much damage, that the repair enzymes cannot keep
up (ex: UV sunlight radiation).