Question

1) 4pts - The presence of glucose in the environment prevents lots of lac operon expression, while glucose’s absence greatly increases expression – discuss how ATP concentration, adenylyl cyclase, and CAP/cAMP and holoenzyme increase lac operon expression.

2) Discuss how promoters, enhancers and the TF proteins that interact with them are used in eukaryotic cells to control transcription of housekeeping genes versus cell specific/regulated genes? Be specific about everything’s role – what binds where and does what!

A) 4pts - Housekeeping genes –

B) 4pts - Regulated cell specific genes -

3) 3pts - Discuss the three types of domains and their structural motifs found within typical transcription factors. What do these domains allow the TF to do?

Answer 1

answer) ATP concentration increase lead to decrease in camp thus there is decrease in low transcription of lac operon.

- The CAP binding site is a positive regulatory site that is bound by catabolite activator protein (CAP). When CAP is bound to this site, it promotes transcription by helping RNA polymerase bind to the promoter. CAP is regulated by a molecule called as cAMP ( cyclic AMP ). BINDING OF cAMP leads to change in confirmation of CAP, promoting it binding to DNA AND THUS increase transcription - lac operon on.

- RNA polymerase is also known as holoenzyme binding to promoter lead to lac operon expression. any mutation in promoter region or in structure of RNA POLYMERASE result unable of RNA POLYMERASE binding to Promoter, thus no transcription from lac operon.

- absent of glucose lead to increase in adenyl cyclase which convert the AMP into cAMP which further binding to CAP would increase the binding affinity of RNA POL TO promoter ultimately leading to lac operon induction

answer 2 ) transcription factor is complex made of TATA binding protein and associated factors TATA binding protein is DNA SEQUENCE SPECIFIC protein which bind to minor grove of DNA . This act as recognition centre for RNA polymerase to intiate transcription factor. Enhancer are long range regulatory element which increase basal level of transcription initiated through the core promoter elements. Enhancer are usually 100-300 bp long and have binding sites for transcription factor .

House keeping gene are constitutively express within cell.Their promoter lack of TATA OR CAAT BOX. house keeping gene promoter have series Of GC box which provide binding site for transcription factor . Transcription are specially enriched other the housekeeping gene promoter are transcription factors and regulated by Special enhancer specific to housekeeping while in case of regulatory gene which are specific to cell and expression is highly regulated process depending on various cell type and function.

house keeping gene regulatory gene

constitutively express highly regulated and control in expression

QRT PCR - Stable expression unstable expression

highly conserved and evolve slower tissue specific and higher evolution rate

example actin , 18S rRNA myelin basic protein

answer) there are various domain present in transcription factor which include 3 domain

DNA BINDING DOMAIN : this domain bind specific to DNA sequence used to derive to transcription of gene. The domain have various structural motif which include helix-loop-helix, leucine zipper motif etc.

Activation domain : these act as binding sites dor Transcription coregulator. These domain motif includes acidic domain, glutamine rich domain, proline rich domain and isoleucine rich domain

Signal sensing domain (SSD) : these act as signal responder, thus it sense signal and transmit it to whole transcription complex, act as regulator which can result in up or down regulation of gene expression.