1. What are the four roles that DNA must play in cells? How is the structure of
ID: 12535 • Letter: 1
Question
1. What are the four roles that DNA must play in cells? How is the structure of DNA consistent with these roles?2. Match the terms with the most suitable description.
_____ X-rays a. parts of mature mRNA transcript
_____ chain elongation b. base triplet for amino acid
_____ exons c. second stage of translation
_____ genetic code d. base triplet that pairs with codon
_____ anticodon e. one environmental agent that induces mutations in DNA
_____ intron f. set of 64 codons for mRNA
_____ codon g. the parts removed from a pre-mRNA transcript before translation
3. Complete the following:
Original DNA sequence: TACAATCGGCTT
DNA replicated sequence: _______________
mRNA sequence from the original sequence: ____________________
4. The nucleotide sequence of a DNA codon is GTA. In an mRNA molecule transcribed from this DNA, the codon has the sequence ___. In the process of protein synthesis, a tRNA pairs with the mRNA. The nucleotide sequence of the tRNA anticodon is ___. The amino acid attached to the tRNA is ___.
Explanation / Answer
1. DNA plays the four roles of replication, transcription, recombination, and mutagenesis in cells. Let's examine the structure of DNA. It's a double helix composed of the amino acids adenine, guanine, thymine and cytosine. The double helix structure is unzipped by enzymes during replication so that amino acids can bind to each parent strand in semi-conservative replication to produce two final duplicates. Transcription is heavily reliant on the accuracy of the amino acids to bind to their respective match. In every case of DNA rearrangement DNA forms unusual structures. During recombination, sharp bends and Holliday structures are the most distinctive changes to the DNA structure. Mutangenesis occurs when deletions and insertions (mutational hotstpots) or changes to the DNA structure happen when certain amino acids aren't properly determined during replication. Think about how these process occur. What is it about DNA that allows these processes to run smoothly and accurately. 2. e c a f d g b 3. Remember that G always pairs with C and A always pairs with T in DNA replication. In mRNA the T is replaced with the amino acid U, so therefore in the sequence TACAATCGGCTT DNA replicated sequence: ATGTTAGCCGAA mRNA sequence from the original sequence: AUGUUAGCCGAA 4. Based off of the knowledge in question #3 we can determine that the DNA codon of GTA will have an mRNA sequence of CAU. During the process of protein synthesis, tRNA has to be an anticodon that pairs with the CAU resulting in the sequence of GUA. Different codons code for different amino acids and consequently GUA codes for the amino acid valine.
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