operon questions

Answer as Directed. Below is the model of a lac operon. lac I lac Z с promoter operator lac Y lac A DNA +1 1. What are structural genes? Are the lac structural genes transcribed in the absence of lactose? 2. What is the role of the promoter and operator sites in the operon? 3. Is the repressor protein bound to the operator site in the absence of lactose? In its absence? 4. Under what nutritional circumstances (high or low glucose) is CAP bound to cAMP? 5. In the absence of lactose and the presence of glucose in the bacterial growth media, what proteins are bound to the lac control region? Is the operon being transcribed then? 6. In the presence of lactose and the presence of glucose in the bacterial growth media, what proteins are bound to the lac regulatory region? Is the operon being transcribed then? 7. In the presence of lactose and the absence of glucose in the bacterial growth media, what proteins are bound to the lac control region? 8. Why is it adaptive for a bacterium to not…

Answer as Directed. Below is the model of a lac operon. lac I lac Z с promoter operator +1 lac Y lac A DNA 1. In the absence of lactose and the presence of glucose in the bacterial growth media, what proteins are bound to the lac control region? Is the operon being transcribed then? 2. In the presence of lactose and the presence of glucose in the bacterial growth media, what proteins are bound to the lac regulatory region? Is the operon being transcribed then? 3. In the presence of lactose and the absence of glucose in the bacterial growth media, what proteins are bound to the lac control region? 4. Why is it adaptive for a bacterium to not express the genes that encode for that lactose utilization proteins when lactose is not available or when glucose is present? 5. Why is it adaptive for the structural genes for using lactose to be under the control of a single promoter, i.e., synthesize a polycistronic message rather than three monocistronic message?

P₁0 ORF1 t₁ ORF2 ORF3 t₂ The diagram above illustrates an operon that is regulated by the RepR protein. O A small molecule, X, is needed to enable RepR to bind to the operator (O). When X is absent, which of the following statements is most accurate? O RNA polymerase binding to the P₁ promoter is unblocked Equal amounts of ORF1, ORF2, and ORF3 are made Expression of ORF2 and ORF3 is prevented by the terminator t₁ O Expression of ORF1, ORF2, and ORF3 is de- repressed

Read aloud V Draw Highlight 2. You are studying the regulation of the lactose operon in Escherichia coli, by measuring expression of the lacZ gene (i.e production of beta-galactosidase). (a) You identify several loss-of-function mutations in which lacZ is never expressed, in the presence and absence of glucose and lactose. What components of the lac operon could be mutated to produce this phenotype? List all possibilities. (b) You identify another loss-of-function mutation with the following expression pattern: Media + glucose - lactose + glucose +lactose - glucose - lactose - glucose + lactose lacZ expression Low Low High High What components of the lac operon could be mutated to produce this phenotype? List all possibilities.

Explain how the Lac operon functions when there are low glucose levels and high lactose levels.  Be sure to address the regulatory and structural gene region of the operon and how each of the following function: CAP, cAMP, RNA polymerase and the repressor protein.

40-How can understanding the gene expression pattern in a cancer cell tell you something about that specific form of cancer? 1-In E. coli, the trp operon is on by default, while the lac operon is off. Why do you think that this is the case?

I. Answer the following: 1. What are the main elements of the lac operon and their functions? 2. Distinguish among inducible, repressible, and constitutive gene operons.

Part A If E. coll bacteria are placed in an environment that contains both glucose and lactose, the regulation of the lac operon will allow which nutrient to be processed first? ONether will be processed in this environment O Both will be processed at the same time. Glucose O Not enough is known about the regulation of the lac operon to know which nutrient will be processed first Lactose Submit Request Answer

amount of protein / amount of mRNA 12 mm / ↑ A B time (minutes) 20 Bacteria were grown in culture. At various time points, substances were added or removed from the culture medium. To assay the effects of the substances on operon gene expression, samples of bacteria were collected at one-minute intervals and levels of specific proteins and mRNAs were determined. If the operon under investigation is a repressible operon, which arrow indicates the addition of a molecule that binds the repressor protein?

Answer the following questions based on the lac Operon metabolic pathway.   The lac Operon regulates the metabolism of what molecule?     Is this metabolic pathway is catabolic or anabolic?     How many genes are regulated by lac Operon?     What binds to the operator when lactose levels are low?     What happens when lactose levels are high?

12a. In what condition is the LacZ gene transcribed? ANSWER (in one sentence) 12b. Fill in the following table about the Lac operon (LacZ gene) Environmental Condition + Glucose and + Lactose Glucose and + Lactose - Glucose and - Lactose + Glucose and - Lactose Q 2 Body" W #3 E D Which proteins bind to the LacZ promoter? ANSWER ANSWER ANSWER ANSWER $ 4 A R F B % 5 I T MacBook Pro A U 6 G Y & 7 H Is LacZ transcribed? (Yes or No) ANSWER ANSWER ANSWER ANSWER |||| U 8 K

1c  In context with transcription of prokaryotic genes briefly describe the effect the lac repressor protein has on transcription of the lac operon when it is bound to its binding site and the lac operon promoter, and how it accomplishes the effect.

Indicate whether each of the following statements about the lac operon are true or false: Bacteria with a lac phenotype are unable to use lactose because of some defect in expressing the genes A constitutive Lac+ phenotype could mean either that the production of repressor is defective or that the operator sequence is defective The lacl gene is next to, but is not part of, the lac 1. TRUE operon 2. FALSE Bacteria with a lac* phenotype cannot grow on media containing lactose as the only sugar The structural genes of the lac operon are each transcribed as a separate MRNA Expression of the Lac Repressor from the lacl promoter is regulated by lactose

127. Whicn of the following statement concerning the regulator gene (i) associated with the lac operon is correct ? (1) MRNA is transcribed from the i-gene whether lactose is present or not. (2) MRNA is transcribed from the i-gene only when lactose is not present (3) Lactose inhibit the synthesis of mRNA from i-gene (4) Lactose promotes the synthesis of mRNA from i-gene

Describe the probable genetic defect that abolishes the sensitivity of the lac operon to the absence of glucose when other metabolic operons continue to be sensitive to the absence of glucose.

Choose correct option and do explain plz.  1. The protein complex that helps RNA polymerase to cross nucleosomes during extension is:a. SWI-SNFb. poly A polymerasac. TFIISd. FACT 2. The polydenylation is carried out by:a. primaseb. polymers poly ac. a reverse transcriptased. adenylyltransferase 3. The lactose operon produces a polycistronic mRNA that includes four genes: Lacl, LacZ, LacY and LacA. True or false?

1) A. What is the difference between a repressible vs, an inducible operon?   B. Using diagrams and words, describe how the Lac Operon is regulated by different levels of lactose and glucose. Be sure to show what’s happening at the molecular level, including the roles of lactose, glucose the repressor protein, cAMP and CAP.

You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan.  Using your knowledge of operons and their regulation, answer the following questions  I really need a in depth epxplantion for the queshtions to make sure i understand the answers    a.What effect does lactose have on the bacterial cell’s lac operon?    b.What does the absence of glucose do to the bacterial cell?    c.You now add tryptophan to the cell. What would happen to the bacterial cell and its trp operon?   d.What kind of regulation does lactose provide to an operon’s repressor?

The lac operon contains three genes: lacZ, lacY, and lacA for ß-galactosidase, galactoside permease, and thiogalactoside transacetylase, respectively. The operon also contains a promoter site and an operator site. The regulatory gene includes the I gene for the Lac repressor protein and a promoter for that gene. regulatory gene DNA P₁ lacl gene The lac operon undergoes negative regulation. In the normal condition, the Lac repressor protein is active. Allolactose, an isomer of lactose, is the signal molecule that binds to the Lac repressor. P O Increase in gene products The I gene is disabled. Lactose is present in the cell. The Lac repressor dissociates from DNA. lac operon lacZ gene Determine which events will increase the concentration of lac gene products and which will decrease the concentration of lac gene products. Allolactose is not present in the cell. lacy gene lacA gene Decrease in gene products Allolactose binds to the Lac repressor protein. The Lac repressor remains bound…

8:20 ■■ LTE < Spring 2024 - Senior Comprehensives (... Question 6ɔ (ividitudtory) In the Lac operon, what happens when allolactose attaches to the repressor protein? a) b) c) the repressor is induced to attach to the promoter RNA polymerase is induced to attach to the operator lactose synthesis enzymes are produced by genes Z, Y,A d) the repressor is inactivated Question 88 (Mandatory) What is the purpose of X-chromosome inactivation in mammals? a) It accomplishes dosage compensation. b) It assists in the interactions beteeen genes Tra and Dsx. c) It prevents trisomy from occurring. d) It produces the testis determination factor. Question 94 (Mandatory) Duchenne muscular dystrophy is inherited in an X- linked recessive pattern. A female is known to be heterozygous for Du muscular dystrophy XD xd

. Recall that the trp operon has a special leader sequence (trpL) between the operator and the structural genes that offers attenuation as a mechanism for regulation of gene expression. (A) Draw a diagram of a trpL region of the operon when tryptophan is abundant in the cell.Label the following features: the DNA, 5’ and 3’ polarity of the RNA, the regions 1, 2, 3,and 4 and poly-U of the RNA, the pair of Trp codons (UGG), the ribosome, and RNA-Pol,along with any stem-loop structure that would form under these conditions (B) In the above example, will the rest of the trp operon genes be expressed? Briefly describe your reasoning why or why not  (C) The trp codons in region 1 of the trpL gene have mutated to cysteines (UGG to UGC). What will be the effect on attenuation gene regulation of the trp operon? Brieflyexplain your reasoning.

1e regulation of the lac operon by cAMP-CAP complex is an example of positive regulation. what in general does it mean to say that a gene or operon is subject to positive regulation?

You decide to work on mutant strain 2. You introduce a wild-type operon into these mutant bacteria - i.e. an operons with fully functional regulatory and operon genes - to see if you can restore function. 5. When you add ethanol to these modified bacteria, the expression of genes C and D would be ( Select] 6. When you remove the ethanol, the expression of genes C and D would be ( Select )

The molecules indicated below can be used experimentally due to their roles in relation to the expression of the lac operon.  Drag the listed molecules to their corresponding bin. Reset Help   ONPG IPTG X-Gal allolactose     Dragable beta-galactosidase cleaves this molecule to form a visible yellow product.   beta-galactosidase cleaves this molecule which then dimerizes to form a visible blue product.   This molecule induces the transcription of the lac operon by inactivating the lac repressor.

The TRP operon functions by attenuation. Briefly explain how attenuation works and why it is necessary, in addition to the repressor protein, in regulating the operon.

Answer the following questions: 1. Given the following genotypes, explain how the mutation (identified by a () superscript will affect E. coli grown in lactose medium. Will the lac operon be on or off? Will there be a complete set of gene products from the loc operon? What will be the implication of the missing gene product, if ever? Will the cell be able to survive in the lactose medium or not? a. p' oE Y b. p'o Y d. po v

explanation summary   You now add tryptophan to the cell. What would happen to the bacterial cell and its trp operon?

The next set of questions are all related to the following operon: This figure represents the ABC operon, which is a negative inducible operon, and its associated regulatory gene. The structural genes produced by the operon convert molecule A into molecule D. When molecule A is present in the environment, it will bind to the regulatory protein, and operon expression will be induced. operator testR T testR promoter regulatory protein testP testo structural genes test2 test1 T test1 test2 Where is the regulatory protein when there is NO transcription? test3 test3 structural proteins It is floating in the cytoplasm (not attached to the operon) with molecule A attached. It is floating in the cytoplasm (not attached to the operon) without molecule A. It is bound to the operator without molecule A. It is bound to the operator with molecule A attached.

Assuming that the level of glucose is low, a mutation in the repressor associated with the lac operon of E. coli which prevents binding of the repressor to lactose should result in_____   Constitutive expression of the lac operon genes ito sagot ko Lack of expression or reduced expression of the lac operon genes under all circumstances  Expression of the genes only when lactose is present  Expression of the genes only when lactose is absent

Describe the main functional differences between the TRP and the Lac operons. Main functional differences DO NOT refer to the fact that one operon involves TRP and the other involves Lac. They also don’t include that there are different genes found in the TRP operon compared to the Lac operon or that the repressor in the Lac operon is called Lac l. Also DO NOT simply list how both operons work to answer this question.