Exam2key.07 - Bio 221 Name_Key_ Exam 2 Please tear off the...

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Bio 221 Name______________ Key _________________ Exam 2 Please tear off the first page of your exam and turn it in along with your scantron sheet. You may keep the rest of the exam. Short answer. 5 points each. 1. Make a sketch showing the processes of transcription and translation in a 2 gene operon in a prokaryote . Include the following in your drawing: DNA as solid lines ( ) - label the + and - strands, the 5’ and 3’ ends (antiparallel, template is - and is read 3’ to 5’) RNA as a dashed line( ) - label the 5’ and 3’ ends (from promoter to terminator) Protein as a dotted line( ) (from AUG to UGG, two proteins shown) Promoter as an arrow ( ) (on DNA, not RNA) Terminator as a hairpin loop (can show either on DNA or RNA or both, but NOT on protein) Shine Dalgarno sequence underlined (upstream of AUG for each protein in the operon, on RNA) Start codons (AUG) (two of them, one for each protein) Stop codons (UGG) (ditto) (Other versions of this may be correct, too, as long as the conditions above are met.) 2. The following gene is inducible under both negative and positive control. The negative control inducer is present , and the positive control inducer is absent . Indicate the location of the positive and negative control proteins (whether bound to the DNA or not), and label appropriately: the activator the repressor the inducer the operator the activator binding site gene promoter 5’ 3’ 3’ (+) 5’ (-) 5’ 3’ SD SD AUG UGG AUG UGG activator (not bound to DNA) inducer repressor (not bound to DNA) activator operator binding site
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3. On a visit to Kenya, you notice that many women in a village have swollen livers and test positive for schistosome eggs. You also find that they do laundry in a pond near the village. You suggest killing all the snails in the pond as a means to stop the spread of disease. Is this a reasonable suggestion? Explain. Yes. The schistosome life cycle involves the snail as a biological vector. Miricidial larvae are ingested by the snail and develop into cercarial larvae, which can infect humans. So killing the snails would prevent formation of the form of the schistosome larva that infects humans. 4. List the steps in the replication cycle of an animal virus. 1. Attachment of phage proteins to host receptor 2. Entry of phage into host by membrane fusion or endocytosis 3. Uncoating - release of nucleic acid from nucleocapsid (transit to site of replication) - this step is optional 4. Nucleic acid replication, transcription and translation 5. Maturation (assembly) 6. Release from the host by budding or exocytosis 5. Answer EITHER A OR B (not both). A. Describe the steps involved in the activation of a T H cell upon recognition of a specific antigen by the T cell receptor. B.
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This note was uploaded on 04/07/2008 for the course BIOL 221 taught by Professor Walter during the Spring '08 term at Purdue University-West Lafayette.

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Exam2key.07 - Bio 221 Name_Key_ Exam 2 Please tear off the...

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