5. CBL on Bacterial Gene Regulation (AY2019-20) by Koh Siok Im

5. CBL on Bacterial Gene Regulation (AY2019-20) by Koh Siok Im https://padlet.com/silkoh/lcf51f8iyfxb Jacob and Monod Juniors en-us 2018-11-23 04:13:12 UTC 2025-10-02 23:49:29 UTC hello@padlet.com https://padlet.net/icons/png/1f913.png Andre Neo DBS/FT/1B/02 https://padlet.com/silkoh/lcf51f8iyfxb/wish/411782061 Are the three genes LacZ, LacY and LacA always needed to be together (in that certain pattern) for transcription to happen?
Ans
Yes,they are all related to lactose metabolism --Koh SI

]]> 2019-11-15 14:10:54 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/411782061 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412161743 What happens when there is high glucose and lactose? Is lactase still produced? by who??]]> 2019-11-16 08:36:54 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412161743 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412190689 How does low glucose concentration stimulate an increased cAMP concentration ?

- Ryan Wong

]]> 2019-11-16 13:47:24 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412190689 Are the 3 lac enzymes produced only when lactose is present? https://padlet.com/silkoh/lcf51f8iyfxb/wish/412213612 Yew Jing Zhi DBT/FT/1B/02

]]> 2019-11-16 16:33:00 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412213612 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412221789 Are LacA,LacY,LacZ always produced at the same time?
Kessler DBT/1B/02]]> 2019-11-16 17:25:58 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412221789 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412276478 Are the three genes Lac Z. Lac Y and Lac A always needed to be together(in that certain pattern) for transcription to happen?

Andre Neo DBS/FT/1B/02

(This question has been answered below, just reposting to put my name)

Ans
Yes, they are all related to lactose metabolism --Koh SI]]> 2019-11-17 01:38:56 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412276478 If Lac Z is involved in the digestion of lactose into glucose and galactose, as well as Lac Y is involved in the permeability of cell membrane to absorb/ transport lactose into the cells, what is the function of lac A in lac operon? https://padlet.com/silkoh/lcf51f8iyfxb/wish/412289305 Goh Zong Han (DBS/FT/1B/03)

]]> 2019-11-17 03:33:58 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412289305 1. Is the catabolite activator protein (CAP) a requirement for the transcription of the structural genes of the Lac operon, or does the CAP protein merely enhance and increase the transcription process? 2. Along the DNA sequence, which regions are included/considered as the Lac operon? The regulatory gene (Lac I), controlling sites (CAP-binding sites, Lac P promoter region, Operator region) the 3 structural genes (Lac Z, Lac Y and Lac A), and /or terminator sequence. https://padlet.com/silkoh/lcf51f8iyfxb/wish/412294296 Iffatun Nadhirah binte Muhamad Lathif (DBT/FT/1B/02)]]> 2019-11-17 04:33:06 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412294296 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307012 1. It is said that enzymes are reusable in the sense that they are chemically unchanged by the end of the reaction, going by that logic it would make sense that the enzymes produced here will stay on in the bacteria after all the lactose has been broken down. However this does not seem to be the case. Hence what are the mechanisms present to break down the enzymes present as to not waste resources and to prevent enzymes such as beta-galactosidase from building toxic products by acting on other galactosides.
Shawn Wang DBT/01]]> 2019-11-17 07:02:13 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307012 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307086 Is the lac operon sequence found in every strand of the E.coli's DNA or just some?
Are all the strands of DNA identical?
Quek Lin, Melody (DBS/FT/1B/02)]]> 2019-11-17 07:03:07 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307086 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307431 Why is lac operon a positive control? What does it mean?
Goh Marlene DBS/02]]> 2019-11-17 07:06:24 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307431 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307487 What would happen if the Lac I gene is mutated?
Cheryl Leow Wenxuan (DBS/01)]]> 2019-11-17 07:07:03 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412307487 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412315876 1. Why is there more cAMP in the absence of glucose
2. How does binding to the operator prevent the transcription of the 3 enzymes. Why can't the RNA polymerase bind to the gene after the repressor?
Lim Si Hui Kelsey (DBS/02)]]> 2019-11-17 08:47:47 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412315876 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412318060 1. How is the lac operon being regulated?
2. What are the proteins that are being encoded?
Ryan Ang Jun Wen (DBS/02)]]> 2019-11-17 09:12:21 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412318060 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412319836 What are the specific functions of the enzymes coded by lacZ, lacY and lacA?
Amelia Ng (DBS/01) ]]> 2019-11-17 09:30:54 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412319836 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412330799 1. Why must lactose be converted to allolactose before binding to lac repressor?
2. Since RNA polymerase will move along the dna operon from the promoter region to lac Z then to lac Y and lac A region during transcription. When there is no/low glucose, how is lac i gene going to be transcripted to form lactose repressor when RNA polymerase only binds to the promoter which is on the right of the lac i gene region? Is it that there is another promoter region further on the left of lac i for the rna polymerase to attach and lac i gene to be transcripted?
-Sharon Beh DBT/FT/1B/02]]> 2019-11-17 11:08:54 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412330799 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412334205 1. How does the lac repressor protein bind to the lac operator site?
2. How does the protein encoded by lac A gene participate in the metabolism of lactose?
3. How exactly is lactose converted into allolactose in the cell?
- Ng Xin Hui DBT/FT/1B/02]]> 2019-11-17 11:38:46 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412334205 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412340356 1. How does the conformational change look like when allolactose binds to an allosteric site on the repressor protein.
2. What are the bonds involved in the binding of allolactose to the repressor protein?
3. How is lactose converted to allolactose?
4. How small is the amount of lactose being converted to allolactose?
Ang Rui Min DBS/FT/1B/01]]> 2019-11-17 12:32:55 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412340356 Ruimin_19 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412341341 1. How does the conformational change look like when allolactose binds to an allosteric site on the repressor protein.
2. What are the bonds involved in the binding of allolactose to the repressor protein?
3. How is lactose converted to allolactose?
4. How small is the amount of lactose being converted to allolactose?
Ang Rui Min DBS/FT/1B/01]]> 2019-11-17 12:40:03 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412341341 Keng heng DBS/FT/1B/01 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412347626 1. What is between lacl and lacp
2. why is there still LacZ, LacY and LacA made even though there is only the presence of glucose, as shown in the table jacqueline and marcus drawn from the experiment.

]]> 2019-11-17 13:32:12 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412347626 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412349613 What is the significance of beta-galactosidase, lactose permease and transacetylase being transcribed in this order?
How would the process be affected if the lac Z, lac Y and lac A were arranged differently on the lac operon?
Nicole Loh (DBS/02)]]> 2019-11-17 13:48:18 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412349613 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412488792 1. How is the lac operon regulated?
2. How are proteins encoded
Petrina foo DBT/1b/02]]> 2019-11-18 02:17:56 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412488792 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412504522 1. How does the lac repressor prevent the expression of the lac genes?

2. What happens to the lac operon when there is no glucose or lactose present?
- Angelina Callista Setiawan DBT/FT/1B/02

]]> 2019-11-18 03:24:47 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412504522 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412538266 What is the allolactose composed of? And how much of the lactose is converted to allolactose? So in short, if glucose is present, there will be low levels of amp, which leads to no transcription? Why is this process so important; what does lactose help to break down in our body?

Aarthi Kannan DBT/02 ]]> 2019-11-18 06:37:24 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412538266 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412615972 why does the mRNA expression levels of Lac 1 fluctuate?
janelle hiou dbs 04]]> 2019-11-18 11:10:28 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412615972 Sim Pearlynn DBT/1B/01 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412626797 1. About allolactose: How does allolactose form from lactose & how does allolactose cause the repressor to change shape?
2. If glucose is replaced by other simple sugars such as fructose or galactose, can transcription still occur?
:)]]> 2019-11-18 11:49:14 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412626797 Nivrithi DBS/1B/03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412634842 What would be the consequences of any mutations in lac I gene?
]]> 2019-11-18 12:16:46 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412634842 Irina DBS/FT/1B/01 irinuhvoo https://padlet.com/silkoh/lcf51f8iyfxb/wish/412635820 1. At the moment when lactose enters the cell, is the lac repressor bound to lac operator site?
2. If the lac repressor is bound to the lac operator, how does B-galactosidase get produced in order to break down lactose to allolactose?
3. Do all 3 enzymes produced from lac Z, lac Y and lac A have the same role in breaking down lactose?]]> 2019-11-18 12:19:50 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412635820 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412642612 1. How does the formation of allolactose occur from lactose?
2. Since glucose is preferred by the body as compared to lactose, will there be any negative effects on the body if there was no lactose at all?
Hanisha Hamid DBT/FT/1B/02 ]]> 2019-11-18 12:41:08 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412642612 Alicia Teo DBT/1B/02 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412644988 What does the protein Transacetylase do?]]> 2019-11-18 12:47:25 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412644988 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412646493 The Lac Operon is only an example of positive control or a negative control as well because in the Lac Operon is actually off when the repressor is active.
Cheng Namfon DBS/FT/1B/03]]> 2019-11-18 12:51:27 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412646493 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412647233 If there is a lack of allolactose, can transcription still be performed?
Wileen Tan DBS/1B/03]]> 2019-11-18 12:53:15 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412647233 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412650098 How does IPTG induce the production of the three enzymes needed for lactose metabolism?

Brenda Aw
DBS/FT/1B/04]]> 2019-11-18 12:59:41 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412650098 Jane Goh DBS 04 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412668573 1. Is glucose the only form of sugar that test for the mRNA if only 1 type of sugar is used, or can another form of hexose like fructose be used?
2. Is E coli the only type of bacteria used for this experiment?

]]> 2019-11-18 13:33:02 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412668573 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412681024 What synthesizes gene repressors and what causes them to begin being synthesized?
Philip Sidney Lui DBS/FT/1B/03]]> 2019-11-18 13:50:19 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412681024 Lim Eng Chong DBS/FT/1B/03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412704414 1. Do the 3 enzymes break down lactose at the same rate or differently?

2. What is meant by polycistronic?

3. How can lactose be converted to allolactose by beta galactosidase if beta galactosidase needs to be produced by the lac operon first? The operon is inactive as the repressor is still attached to it and shouldn’t be able to produce any beta galactosidase, thus lactose should not be able to be converted to allolactose.

]]> 2019-11-18 14:19:55 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412704414 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412712540 Is there any circumstances (e.g. abnormal cell organelles) that may cause bacterial gene regulation to not actually work?
Siang Ning, DBS 03]]> 2019-11-18 14:30:21 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412712540 In response to Eng Chong https://padlet.com/silkoh/lcf51f8iyfxb/wish/412715003 1) The enzymes all have different functions. Only beta-galactosidase breaks down lactose.
2) Polycistronic means multiple genes.
3) I think there’s always a low level of beta-galactosidase being transcribed. Since the repressor protein is not permanently bound to the operator but rather comes off and on in the absence of lactose, there could still be transcription, just at a lower frequency.

Brenda Aw
DBS/FT/1B/04

Well said, thank you, Brenda!👍
- Silk]]> 2019-11-18 14:33:34 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412715003 mohamadiman55 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412721707 In what situation is Negative Regulation preferred over Positive Regulation?
Mohamad Iman DBS04]]> 2019-11-18 14:40:58 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412721707 Thung Yee Shien (DBS 04) https://padlet.com/silkoh/lcf51f8iyfxb/wish/412727600 what is the structure of the lac repressor?

what significance does the structure of the lac repressor have on its function?]]> 2019-11-18 14:48:37 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412727600 Boey Mao Yu (DBS 04) https://padlet.com/silkoh/lcf51f8iyfxb/wish/412728292 1. What is the process of Allolactose being formed from lactose?
2. If there is no lactose present, can transcription still take place? Are there any other alternative ways?]]> 2019-11-18 14:49:22 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412728292 Samynathan Ramprakash(DBT/FT/1B/02) https://padlet.com/silkoh/lcf51f8iyfxb/wish/412768236 why lactose need to be broken into simple sugar?Why simple is preferred over lactose?cAMP only present in the presence of glucose?What are the resources needed to digest lactose?

]]> 2019-11-18 15:36:15 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412768236 Alden Oei Jit Sheng(DBT/FT/1B/02) https://padlet.com/silkoh/lcf51f8iyfxb/wish/412774955 1. What happens if there is an isomer of lactose that enters the cell, or if any other sugar is present?]]> 2019-11-18 15:44:26 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412774955 Leow Ching Yan DBT/02 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412777438 1. What happens when there is a lack of allolactose in the body?
2. Does being lactose intolerant have any effect on allolactose?]]> 2019-11-18 15:47:11 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412777438 Sumudu Dulanji DBS/FT/1B/03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412781047 What does mutations in the operator, repressor and promoter cause?]]> 2019-11-18 15:51:19 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412781047 Chloe Lin Ying Xuan DBS 03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412782104 1.What are the differences between the operon and cistron?

2.Is the Lac Operon Inducible orrepressible?

]]> 2019-11-18 15:52:35 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412782104 Seet Quan Kai Chester DBS 03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412787073 1. Are there other operons besides Lac Operon?
2. Will allolactose always be present together with Lactose?]]> 2019-11-18 15:58:15 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412787073 Louisa DBS/FT/1B/03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412797335 How are eukaryotes able to breakdown lactose? Does it use similar enzymes from lac/trp operons to help in this process?]]> 2019-11-18 16:08:20 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412797335 NATANIA DBS/04 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412816605 What happens if there are mutations in the operon?]]> 2019-11-18 16:29:29 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412816605 Leonard DBS/FT/1B/03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412820840 (1) Does gene regulation apply to plasmids, chloroplastic DNA and mitochondrial DNA as well? If so, are there any prominent examples of this?

(2) What cleaves the lacZ, lacY and lacA into 3 individual chains of mRNA from just 1 strand right after transcription?]]> 2019-11-18 16:34:33 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412820840 Lien En Qi DBS 04 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412835750 what happens if an LAC operon is missing ?]]> 2019-11-18 16:53:05 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412835750 Ng Man Xuan DBS03 https://padlet.com/silkoh/lcf51f8iyfxb/wish/412894487 1.The significant of TATA box, how does it work?
2.Where are the operator produced and how do they know when to be activated or when they are needed?
3. Where are the repressor made?]]> 2019-11-18 18:06:14 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/412894487 Quah Yan Hui (DBT/FT/1B/01) quahyanhui https://padlet.com/silkoh/lcf51f8iyfxb/wish/413095983 How is LacZ, LacY and LacA still being produced despite the lack of lactose?

]]> 2019-11-19 00:10:53 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413095983 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413096041 what would happen if mutation ever occurs on the LAC genes
Tan Li Xuan DBT/02]]> 2019-11-19 00:11:05 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413096041 Xavier Ng Zhuan Li (DBT/FT1B/01) https://padlet.com/silkoh/lcf51f8iyfxb/wish/413096312 Why does only allolactose bind with the repressor protein why not lactose?is there any difference in their activity with the repressor?]]> 2019-11-19 00:12:08 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413096312 Is the enzyme that creates allolactose regulated by the operon system? https://padlet.com/silkoh/lcf51f8iyfxb/wish/413097954 Chua Yau Hong (DBT/1B/01)]]> 2019-11-19 00:17:45 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413097954 Jovian DBS/FT/1B/04 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413156481 Can the allolactose still bind to lac repressor when it is already binded to the lac operon?]]> 2019-11-19 03:34:28 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413156481 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413179024 what happens if there is a high amount of glucose and lactose present? will transcription and translation still occur?

neagan dbs 03]]> 2019-11-19 05:38:32 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413179024 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413311758 Does the absence of other sugars rather than glucose activates the Catabolite Activator Protein?
Renee Tan (DBS/FT/1B/02)

]]> 2019-11-19 13:02:02 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413311758 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413425261 1. Why is there a need for Trp operon instead of other operon for other amino acids? Is it related to trp codons being non-degenerate?
2. What happens to the partially transcribed leader mRNA if a terminator hairpin 3-4 structure is formed, prematurely terminating the transcription?
3. Why must the repressor monomer form a tetramer to be a negative trans-acting factor?
Celest Tay (DBS/02)]]> 2019-11-19 15:34:48 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413425261 Javier Teng DBS/1B/04 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413740137 Is there such an operon gene present in eucaryotes as well? If so, is a mutation of it the cause for lactose intolerance? ]]> 2019-11-20 00:14:18 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413740137 Jeremiah DBS 1B 02 tangjere https://padlet.com/silkoh/lcf51f8iyfxb/wish/413790136 What are the regulatory features of a lac operon?

Would there be any instance where Lac Z,Y,A stop producing?]]> 2019-11-20 02:54:49 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413790136 Yu Heng DBS/1B/02 https://padlet.com/silkoh/lcf51f8iyfxb/wish/413790843 What allow eukaryotes to break down lactose?
What happens when gene regulation does not work?
What are the other operons other than Lac Operon

]]> 2019-11-20 02:57:19 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413790843 Navena Baskaran (DBS/1B/02) https://padlet.com/silkoh/lcf51f8iyfxb/wish/413797712 What happens if the inducer was lactose? What is the difference in activity between lactose and allolactose with the repressor?]]> 2019-11-20 03:26:17 UTC https://padlet.com/silkoh/lcf51f8iyfxb/wish/413797712