Spring 2018 Genetics HW 5 Due Fri March 2 at 5. Worth 10 points as always Give t

Question

Spring 2018 Genetics HW 5 Due Fri March 2 at 5. Worth 10 points as always Give these a good "college try" before asking for help. It is when you do so that you learn best. Operon questions 1. Describe operons in your own words, as if you were explaining what an operon is to someone who knew about DNA and cells etc but did not know what an operon was. (2-3 of sentences.) Here are some things you can discuss: Are operons controlling transcription or translation? Which organisms are they found in? What do the genes in an operon have in common with each other? 2. The trp operon vs. the lac operon: (Which one of these is activated in the presence of a substance, and which is activated in the absence, and why the difference? In other words, what if the cell could think, what would be its rationale for why one is activated in the presence and the other in the absence of something?) (ignore the effects of glucose in the lac operon) 3. Why does the presence of glucose repress the lac operon? (Why does the cell want it that way?) 4. Describe the process of attenuation in your own words, What is being controlled, and why? 5,6 points) Pick six partial diploid” lac operon problems from the lac operon practice sheet. Figure out the answer. Pick ones that we either didn't do in class, or that you don't remember the answer to. Don't everyone pick the same ones. This is practice for the test where you have to do your own. Then do a bunch

Explanation / Answer

1) The gene regulaion occurs at the level of transcription in bacteria is explained by operon model. An operon is a unit of bacterial gene expression and regulation, which includes structural genes and regulatory sequences recognized by regulatory gene products. An operon consists of cis acting regulatory elements (promoter and operator) and protein encoding structural genes.

2) The lac operon is an inducible operon. An inducible operon is one that is expressed in the presence of a substance, inducer. An inducer is a small molecule that triggers gene transcription by binding to a regulatory protein, repressor. In lac operon, lactose and its analog lead to the expression of the lac genes. In this, repressor is formed in active state but when effector molecule combines with it, it becomes inactive and cannot bind with operator and hence turns ON the transcription.

The trp operon, required for the synthesis of tryptophan is a negatively controlled repressible operon. It is inhibited by aregulatory protein,repressor. Trp operon is a repressible operon because it is inhibited when an effector molecule is present. In this, repressor is in inactive state but when it combines with effector molecule becomes active and binds with operator thereby inhibiting transcription of structural genes.

3) Bacteria prefers glucose as an energy source. So when bacteria finds both glucose and lactose in the medium, it metabolizes glucose and represses the use of lactose, and hence inhibits the transcription of structural genes. This process is termed as the glucose effect.

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.