Download Exam3 - Cornell College

Biology 205
Exam 3
5/4/16
1. Explain the events that occur during termination of transcription and translation. Be sure to include all
major components of each process. Only discuss termination and be specific. (8 pts)
2. List 5 differences and 5 similarities between prokaryotic and eukaryotic transcription. Clearly number
your similarities and differences (1-5). Be sure you focus on transcription and not post-transcriptional
events like intron removal. In order to get credit for each difference, you must include information on both
eukaryotic and prokaryotic transcription. For example, you may not say that eukaryotic transcription does
X and prokaryotic transcription does not. Be specific. (10 pts)
3. A space probe, designed to land on a distant planet, is equipped to obtain samples of material, identify them
according to molecular type and analyze their chemical makeup. Results obtained from samples from planet
205 indicate that the nucleic acid molecules contain just two types of nucleotides. The polypeptides from
this planet are made up of 18 types of amino acids. A double stranded nucleic acid molecule brought back
from this planet contains a total of 280 nucleotides. a) What is the minimum number of bases required in a
code word (codon) in order to code for the 18 types of amino acids and a single terminator codon? (4 pts) b)
What is the maximum number of amino acids that could be incorporated into a polypeptide synthesized
from the nucleic acid molecule that contains a total of 280 nucleotides if only one strand is read and it is a
complete coding strand? (8 pts)
4. Primase is a “sloppy” enzyme and makes many mistakes because it does not have any proof reading
mechanisms. What specific reaction does primase catalyze? Discuss the implications of these mistakes on
DNA replication. Be specific. (8 pts)
5. Explain the energy expenditure for transcribing a prokaryotic mRNA consisting of 10 nucleotides.
Compare this energy expenditure to synthesizing a prokaryotic polypeptide consisting of 10 amino acids.
Be specific. (9 pts)
6. Define or describe the following terms. (10 pts) Be specific.
a) Central Dogma
b) nucleoli
c) aminoacyl tRNA synthetase
d) conservative replication
e) Wobble Hypothesis
7. Starting with the addition of antibody, explain how the detection system allowed us to see blue
hybridization bands on the nitrocellulose membrane. You do not need to list the protocol steps, but you
must explain exactly how the detection system works. (9 pts)
8. The nuclei of eukaryotic cells contain an abundance of stable persisting RNAs (RNA that is always present
in the nucleus and is not transported out of the nucleus). Name two types of RNA that are always present in
the nucleus and explain the specific role of one of the two types in detail. (8 pts)
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9. We discussed two repair mechanisms in class, base excision repair (BER) and mismatch repair. Select one
and describe the type of mutation that is repaired and the details of how the mutation is repaired. Be
specific. (8 pts)
10. The signal recognition particle (SRP) is a small RNA sometimes referred to as the 3rd ribosomal subunit.
What is SRP and describe SRPs function. Be specific. (8 pts).
11. During the detection procedure, we incubated the nitrocellulose membranes in blocking buffer (buffer 2).
What would be the outcome if we skipped this step? Be specific. (8 pts)
12. The structures of the 4 nitrogenous bases found in DNA are provided below. Use these structures to draw
how these nitrogenous bases pair in DNA. You do not need to draw any other part of DNA except the base
pairing of the bases listed below. (6 pts)
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