1. Explain the four roles that DNA plays in cells? How are these roles influenced by DNA’s structure? Be sure you demonstrate your understanding of DNA’s structure in your answer.
(1) DNA must be able to make copies of itself, (2) DNA must encode information, (3) DNA must be able to control cells and tell them what to do, and (4) DNA must be able to change by mutation. The complementarity of the two strands of the double helix explains how DNA can replicate itself, since the sequence of one DNA chain specifies the sequence in the other chain.
2. Match the terms with the most suitable description. __e___ X-rays a. parts of mature mRNA transcript __c___ chain elongation b. base triplet for amino acid ___a__ exons c. second stage of translation ___f__ genetic code d. base triplet that pairs with codon ___b__ anticodon e. one environmental agent that induces mutations in DNA ___g__ intron f. set of 64 codons for mRNA ___b__ codon g. the parts removed from a pre-mRNA transcript before translation
3. What is the importance of the fact that DNA is replicated prior to cell division and what happens if replication does not occur?
Replication before division ensures that the resulting cells have the same exact information. think about what would happen if a cell divided before replicating the DNA. a cell starting with 46 chromosomes would end up making two cells with only 23, which would then make two cells with 11, etc etc until you had no DNA left
4. Using the genetic code table (Fig 10.11 on p 180), take the following DNA sequence and complete the following:
T A C C C C A T G T A A C A T A C C A C T
Complementary DNA strand A T G G G G T A C A T T G T A T G G T G A _ mRNA strand UACCCCAUGUAACAUACCACU
Amino acid sequence YPM.HTT
5. Part of the coding sequence of a gene produces an mRNA sequence of
A U G A A G G C U C C U C C A A G C G G C
DNA sequence ATGAAGGCTCCTCCAAGCGGC
Amino acid sequence MKAPPSG
6. Review pp 178-185 in your book and view the following animation. and Then complete the following table. You may need to watch it the video more than once to catch the details.
Genome British Columbia. 2007. Gene Expression http://www.youtube.com/watch?feature=player_embedded&v=OEWOZS_JTgk Question
Transcription
Translation
What is it, in brief?
[[[[[[the first step in decoding a cell's genetic information the reading of the mRNAs to make proteins
Where does it occur in the cell?
DNA
Amino acids
What is the product?
Rna
protein
Describe how the product is modified to reach its final form. the posttranslational modification of amino acids extends the range of functions of the protein by attaching it to other biochemical functional groups many protein enzymes on and off, thereby altering their function and activity