|Concepts of Biology (BIOL115) - Dr. S.G. Saupe (email@example.com); Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321|
Molecular Genetics - Study Questions
The mortal, living-and-dying individual is the transient care-taker of the instructions that must be conveyed down the generations...An individual life has significance only to the extent that it passes information about its ancestors to its descendents.
Required Reading: Purves et al, Chapter 11 & 12.
Goal of the Unit: The goal of this unit is to provide an introduction to the field of molecular genetics. Our studies will focus on the structure of RNA and DNA, replication and how genes specify phenotype.
Important Terms/Concepts - Replication: (can you use them in a conversation? or make a concept map? or crossword puzzle? or write an essay using them?)
Important Terms/Concepts - Transcription
Important Terms/Concepts - Translation
Important Terms/Concepts - DNA Structure
Learning Objectives: Upon completion of this unit you should be able to:
Explain how the structure of DNA stores information, allows for variability and diversity, mutability (mutation) and exact replication.
Describe Hammerling�s experiments with Acetabularia and explain how these experiments, and those of Gurdon and Steward, demonstrate that the nucleus was the site of the genetic instructions in eukaryotic cells.
Explain why biologists earlier in the century believed that protein, but not DNA, is the molecule of inheritance.
Describe Griffith�s experiments. What conclusions did he derive?
Describe the experiments/contributions of each of the following: Rosalind Franklin, Griffith; Chargaff; Avery et al.; Hershey & Chase; Beadle & Tatum; Watson & Crick; Gurdon
Describe the structure of DNA
Eexplain what a gene is, molecularly speaking, and explain why there is an infinite number of possible genes
Suggest reasons why Avery's conclusion that DNA, not protein, carried the genetic message, was not immediately accepted by biologists.
Answer the questions at the end of the chapter and on-line (course web site)
Matching: Match each of the following with the appropriate scientist
|a. Avery et al.
h. Hershey & Chase
A Replication/Transcription/Translation Question
The following represents the nucleotide sequence in the gene for a short polypeptide (protein). The strand shown is the template (or "sense") strand.
1. Replication: Beneath the template (sense) strand above, write the nucleotide sequence for the non-template (anti-sense) strand of this segment of DNA. Be sure to include the designation for the 3� and 5� ends.
2. During replication of the sense strand, the anti-sense
strand would be made from the:
a. right to the left b. left to the right
3. If the DNA polymerase/replication fork moves along
the DNA from the LEFT to the RIGHT replicating the DNA, the new complementary
strand is made in:
a. one long piece b. a series of short fragments c. impossible to determine from the info provided
4. In the space below, write the nucleotide sequence for the mRNA encoded by this gene. Be sure to indicate the 3' and 5' ends for the mRNA.
5. Circle the translation start codon in the mRNA in #4 above.
6. What is the nucleotide sequence in the anti-codon loop of tRNA that is complementary to the start codon? ______. Indicate the 3' and 5' side of the anti-codon region.
7. What amino acid does the start codon specify? ________
8. Circle the translation stop codon in the mRNA strand in #4 above.
9. Using a codon table (see table in your text), in the space below write the predicted sequence of amino acids for the polypeptide encoded by this gene.
10. Point Mutations - Assume that there is a point mutation in the DNA in nucleotide 6 and it is changed from T, which occurs in the original strand, to A as shown. In the space below, write the amino acid sequence of the polypeptide that would result. How will this mutation would this affect the final protein?
11. More Point Mutations - Assume that there is a point mutation in the DNA in nucleotide 15 (red) and it is changed from G, which occurs in the original strand, to C as shown. In the space below, write the amino acid sequence of the polypeptide that would result. How will the mutation would this affect the final protein?
12. Insertions. Assume that two nucleotides, T and G are inserted in the original DNA strand between nucleotides 4 and 5. How will this affect the polypeptide? Write the sequence of amino acids in the protein below.
13. Which one of the following would be likely to
have the least impact on the final protein? (Explain)
a. an insertion involving one nucleotide
b. an insertion involving two nucleotides
c. an insertion involving three nucleotides
14. Assume that you isolate the polypeptide that was
made in question # above from a piece of �chicken-fried cat.� To your surprise
the protein begins with glycine! What�s the deal?
a. the DNA, like a sleazy cat, lied
b. a methionine amino acid was probably clipped off the protein after translation
c. RNA polymerase made a mistake and inserted an incorrect nucleotide.
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