Week+7b+Prokaryotic+Gene+Expression+v2

.pdf

School

University of California, Los Angeles *

*We aren’t endorsed by this school

Course

7A

Subject

Biology

Date

Apr 30, 2024

Type

pdf

Pages

2

Uploaded by BrigadierMask27955 on coursehero.com

Name _____________________________________________ Transcriptional Regulation in Prokaryotes Pre-Class Worksheet Fill out this worksheet as you complete your pre-class assignments (Textbook Section 17.1). Bring your completed worksheet to class to use as a reference for in-class activities. After completing your pre-class assignments, you should be able to: Define and relate the terms operon, polycistronic mRNA, and structural gene. Label a diagram of the lac operon and state the function of each component. Identify proteins and small molecules that regulate expression of the lac operon. Describe how the lac repressor and CRP regulate expression of the lac operon. 1. Define the following terms: a. Operon b. Polycistronic mRNA c. Structural genes 2. The diagram below represents the lac operon and its regulatory elements. The line represents a double-stranded piece of DNA and each box designates an important region of the DNA. Use the terms in the box below to label each of these regions on the DNA. As you label each region on the diagram also write its function. You may find it helpful to refer to Figure 17.4 in the textbook. lacI gene lacI promoter lac operon promoter ( lacP ) lacY gene lacZ gene CRP-cAMP binding site Operator ( lacO ) LVazquy Robles GingingAMP coding sequence ÉÉÉÉÉ ly gge nte Feagalaectosidase 1 lad gene hep lace gene lacy gene Iacp isthe coding sequence last promoter b to for protein promoted Infiptsaytherase the operator permease it erodes one repressor complex and PFriffription Yaffertfrom the protein tprgg.si fnicmRNAfprgameetaking external medium of the cell The operon is the region of DNA that is made up of the promoter, the operator, and the coding sequence for the structural genes. The polycistronic mRNA includes the coding sequence for beta galactosidase and lactos permease. The structural genes code for the sequence of amino acids makes up the primary sequence of each protein. Several mutation eliminate functions of the lacZ gene and lacY gene.
3. Draw a picture of the mRNA molecule(s) produced by the lac operon and its regulatory elements (refer to the diagram in the previous question). You may find it helpful to refer to Figure 17.4 in the textbook. On the mRNA molecule(s) you draw, indicate the locations of all start and stop codons the mRNA contains. 4. The table below summarizes the function and features of several molecules involved in regulating transcription of the lac operon. Fill in the table as you learn about these molecules and their function. A few parts of the table are already filled out to get you started. Molecule Is it a protein or a small molecule? What other molecules does it bind to? How does this molecule help regulate transcription of the lac operon? Repressor Lactose and lac operon DNA Lactose cAMP Small Molecule CRP 5. Which molecule in the table above is considered the inducer for the lac operon? Gigging promoter lacquendery I 111111 CRP cAMP operator lacy coding binding site sequence FE at protein B galactosidase lactose permease protein small molecule Edney CRP protein RNA polymerase lactose Repressor covers part of the promoter; it binds to the Operator, preventing RNA polymerase from making mRNA. Inactivates the lactose repressor; prevents the Repressor from binding to the operator site, It allows RNA polymerase to associate with the Promoter and carry out transcription. Binds CRP when glucose is not present, cAMP binds To CRP; it changes the shape of CRP to regulate Transcripts of the lac operon. CRP binds to a site near the operator and Stimulates binding of RNA polymerase to Transcribe lacZ and lacY when lactose is present. It is an allosteric activator of CRP binding.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help