Talk:Lambda phage

Wiki Education Foundation-supported course assignment

This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Faithlawo. Peer reviewers: Faithlawo.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 02:09, 17 January 2022 (UTC)

Title Change

I reverted the move, because the new title got far fewer hits on a Google Test search, and the mover had not changed any inbound links. Most biologists I know usually refer to it as "lambda phage", and it should be so-titled on Wikipedia. The full title can be given in the lead text, but it's wikipedia convention to use the most common term for an article (e.g. Bill Clinton versus William Clinton). --Lexor|Talk 09:00, Oct 12, 2004 (UTC)

Lytic or Lysogenic?

The discussion seems to be overly technical in places. Also, is point 7 under Lifestyle backwards? It seems to say it will lyse unstressed cells and integrate into stressed cells. 24.18.247.19 22:50, 7 January 2006 (UTC)

I think point 7 is correct, shough i am not 100% certain... any other input would be welcome.

Nah, I think point 7 is wrong. Particularly when u consider the fact that if bacteriophage lambda has intergrated a cell via the lysogenic pathway it will change to the lytic pathway if the cell becomes stressed. The process is called induction. Plus, it makes no sense logically, why would it want to integrate into a dying cell? once that cell's dead it can no longer reproduce. Hence the process of induction to lyse any dying cells it is integrated into the chromosome of. --81.109.113.201 16:44, 12 January 2006 (UTC)

I think that the article is wrong about the function of pQ and pN in antitermination. In fact, they allow antitermination by allowing RNA polymerase to bypass terminator regions and not stop codons (which usually have no influence on transcription) Ilyas1978 06:26, 4 September 2006 (UTC)

Ilyas1978 is correct, these descriptions are incorrect. Stop codons are recognized during translation, not transcription (RNA Polymerase doesn't even know what a codon is). The transcriptional stop inhibition, if it really does occur, must be performed in some other manner (i.e., it causes RNAPol to ignore rho sites, which are transcription stop sequences). -- Josh 19:22, 25 October 2006 (UTC)

• Please see this PDF file for information on this (Ilyas is right). I wish I could use some of the images, but they are undoubtedly non-free. --N Shar 01:22, 27 October 2006 (UTC)

Re: point 7 (Lifestyle)

The statement is correct but confusing. When the phage first encounters the cell and all its genes are expressed, the activity of cII depends on the amount of nutrients available, because this controls protease activity. If nutrients are abundant, the proteases actively cleave cII and cause a lytic cycle (counterproductive, perhaps, but evolution does not result in the best possible organism). If nutrients are sparse, cII is not cleaved and the lysogenic cycle begins.

Later, however, when the lysogen is "stressed" by UV light, cI is cleaved by the bacterial protein RecA and the lytic cycle is induced. This is the reverse of what happens initially.

Perhaps it would be best to remove all occurances of the word "stressed" to clarify this. I may do this later when I can log in. --67.125.30.232 17:58, 26 October 2006 (UTC)

Done. I'm not sure I did a good job, so if anyone wants to look at it... --N Shar 01:17, 27 October 2006 (UTC)

Base-pairs of Genome

Why was this changed? My source was my uni notes but I can't find it anywhere else... If anyone can find a number with a reference that would be nice :).

It seems that there are 48,502 base pairs in the circular genome... actually in the phage particle head are 48,490 base pairs of dsDNA and 12 bases of ssDNA at either end of the molecule. These numbers could instead be 48,514 and 48,502... I'm trying to find out for sure.--Gorton k (talk) 15:56, 17 February 2008 (UTC)

Figures

Personally, some figures (especially for the CI/Cro lysogenic regulation section) will really help with understanding for those new to the material. Does anyone know of any good ones [I have the diagram from "Molecular genetics of Bacteria" here]? Jimhsu77479 (talk) 05:13, 18 May 2009 (UTC)

Intruduction revision needed

Can someone revise these sentences: "The phage genes expressed in this dormant state code for proteins that repress expression of other phage genes [what other phage genes? Those natural to the bacterium? What role do they play?]. These proteins are broken down when the host cell is under stress, resulting in the expression of the repressed phage genes"? For the last sentence, wouldn't it be better: "The proteins expressed by the inhibitory phage genes [...] resulting in the expression of the repressed ones"? Wisapi (talk) 20:49, 19 September 2010 (UTC)

Done a bit =) does my edit make matters clearer? It did say "phage genes", which fairly clearly says that they are not "natural to the bacterium", but yes I did need to distinguish the roles of the repressors and the repressed. Hmm will look at the last sentence again... Gorton k (talk) 13:11, 21 September 2010 (UTC)

Cro binding to PL

I notice that there is no mention of cro binding to PL and inhibiting protein N production. However I've not been able to figure out the physiological reason for this binding. Rhodydog (talk) 22:28, 10 May 2013 (UTC)

• Feel free to add this or any other mention of protein interactions to the article. As for the physiological reason for the binding, it's entirely possible that it's not known. There's still a lot we don't understand about lambda phage even after more than half a century of study. §everal⇒|Times 17:33, 11 May 2013 (UTC)

Suggest section

I am a physician, not a biologist. I got here from studying wikipedia on the Irish potato famine and it's causes, both social and biological. I wondered, and address those who are more veteran at things wikipedia. It occurs to me that this article needs a section, perhaps short, geared to an intelligent layman audience, on why this article is rightly classified as high importance. How is that done without going "off topic?" — Preceding unsigned comment added by Purebread (talk • contribs) 16:45, 17 March 2016 (UTC)

If you want to demonstrate importance, I would suggest an additional paragraph in the lede indicating two things that make lambda so notable - it is universally used in molecular biology for the construction and screening of genomic and cDNA libraries, prior to PCR the only way to clone genes, while likewise it served for about three decades as the prototypical example of a complex multi-gene regulatory system and was used to teach these coordinated processes to virtually all graduate students in biomedical fields. Without these dual bases for notability, it would be just another virus. 69.166.47.99 (talk) 22:07, 22 April 2016 (UTC)

Number of genes

The article should mention how many genes lambda has. 2A02:8388:1641:4980:91F8:9D5D:211B:93E3 (talk) 02:18, 8 April 2023 (UTC)