Log in
HomeClass Notes1,200,000IN8,000

BIOLOGY Lecture Notes - Lecture 3: Operon, Acetyl Group, Electronvolt

15 views10 pages
rajchakrab23
4 Apr 2023
School
University of Calcutta
Department
Microbiology
Course
BIOLOGY
Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Lal openon bun gu l afion 1n prokeyyptes. Dna a o i p t i o n a lnel f angulation. Lenl sf sugulation ert tremslukionol l t t f vegealation. claical exompa of gce rugulation 1 n polkoyetes loc opnon. Lactoce also cld leaky opton/ indulible operon-/taboue openo y_ also cld leaky opton/ indulible. 9 s h a p 6 pon tiue mugatinl. Strutwna ongongotiom o a c oponon sn sh i t id iu ty e p u s d. Enhoner; on thus cite aetivoatory profena bimdt cmd pesi biely. On t h i s site j e puusor nd do not allow rna. Trcay a t ig elmants com b psusont. Cis actig tho ceq wvmch otupot of tha gene e a enhanten, operoxtoy. Trans aefing: thos which ou not pont *t omed fmom s0m othu1 qena omd act. Repoumor bind to binds to acivator operator enhanc en teap bindin protein.

Get access

Grade+
$40 USD/m
Billed monthly
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers
Class+
$30 USD/m
Billed monthly
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
7 Verified Answers

Related Questions

1.In the bacterial lac repressor, which of these occurs:

A.In the presence of glucose and the absence of lactose, the repressor is actively produced.

B.The lac operon can be hyper-induced in the presence of low glucose by the 'cAMP binding protein' (CAMP).

C.In the presence of lactose and the absence of glucose the lac operon is repressed.

D.Allolactose is a byproduct of β-galactosidase, indicating high lactose when it builds up.

2 In eukaryotes the enhancer elements can be quite a distance upstream or downstream from the promoter, and transcriptional regulation is helped by protein:protein interactions.

True

False

• Identify the mechanisms for gene expression control in the lac and trp operons

• Explain what transcription factors and regulatory proteins are and how they regulated gene expression in eukaryotes.

• Describe how chromatin structure (DNA methylation and histone modification) can affect gene expression

• Explain the process of protein degradation and its purpose

• Contrast the mechanisms regulating gene expression depending on when they act on: 1) regulating transcription, 2) posttranscriptionally (regulating the mRNA and protein synthesis) and posttranslationally (regulation of protein degradation)

1) In the wildtype (the DNA sequence most commonly found in nature) lac operon, transcription is severely down-regulated. A mutation in lacI that causes an early stop codon in the sequence (called a lacI - strain) results in an operon that has high levels of transcription of the polycistronic m-RNA. What type of regulatory protein is the LacI protein (hint: we covered this type of protein in lecture)?

The Lac regulatory protein is called a repressor. (is this correct)

2) If a bacterium with a wildtype lac operon is grown in the presence of lactose, high levels of transcription result for a while, however, eventually transcription is again down-regulated. If, on the other hand, the sugar IPTG is present (instead of lactose), transcription levels are high and remain high. What function do IPTG and lactose share? How are they differently affected by the operon product? (need help with this question)

Lactose and IPTG affected by the operon are both inducers of the Lac-Operon. (is this correct)

3) What is “epigenetics”? What forms of gene regulation are usually involved in epigenetic control of a trait? Why do we have such a limited understanding of epigenetic processes? (need help with this question)

Epigenetics is the study of phenotype changes that do not change the DNA sequence. Genes can be turned on and off based on environment situations of past generations, (parents or even grandparents) were exposed. Examples of some environmental factors could be diet, stress, smoking, drinking alcohol, and diseases. Histone modification and methylation are usually involved in epigenetic control of a trait. (is this correct)