The Cell and its Organelles Lists of Nobel Prizes and Laureates The Cell and its Organelles Play the Incredible Megacell Game About the game An ultracentrifuge is used for separating the organelles in the cell according to their size, shape and density. The Nobel Prize The 1974 Nobel Laureates in Physiology or Medicine developed methods that made it possible to see and identify organelles, the specialised compartments inside all our cells.Read More » Share this: Share on facebook Share on google_plusone_share Share on twitter More Sharing Services Share on email To cite this pageMLA style: "The Cell and its Organelles". Recommended: The Legacy of Alfred Nobel On 27 November 1895 Alfred Nobel signed his last will in Paris. Play the Blood Typing Game Try to save some patients and learn about human blood types! Unlocking the Secrets of Our Cells Discover the 2012 awarded research on stem cells and cell signalling. Contact E-mail us Press Sitemap A-Z Index Frequently Asked Questions Terms Follow Contact | Press | Sitemap | FAQ | Terms
Lecture Notes October 24, 2013 Introduction We began by reviewing our introduction to levels of regulation in bacterial gene expression from last time. Cells can regulate transcription or translation, or regulate proteins post-translationally. The fastest response will be post-translational and the slowest will be transcriptional. We also reviewed the concepts of positive and negative regulation of transcription. There are examples of both positive and negative regulation of transcription in the lac operon. We reviewed the circuitry of the lac operon in response to three different states: abundant glucose but no lactose, both glucose and lactose, and lactose alone. As shown below, in the presence of abundant glucose but no lactose, cAMP levels will be low, so CAP protein will not bind to the lac operon to enhance transcription. As shown below, in the presence of abundant glucose and also lactose, cAMP levels will be low, so CAP protein will not bind to the lac operon to enhance transcription.
The PCR Method - a DNA Copying Machine Lists of Nobel Prizes and Laureates The PCR Method - a DNA Copying Machine Play the Eye of the Donkey Game About the game PCR is a method by which a few fragments of DNA can be duplicated into millions in a couple of hours. The Nobel Prize The 1993 Nobel Prize in Chemistry was awarded for the invention of PCR, a method that made it possible to copy a large numbers of DNA fragments in only a few hours. Share this: Share on facebook Share on google_plusone_share Share on twitter More Sharing Services Share on email To cite this pageMLA style: "The PCR Method - a DNA Copying Machine". Recommended: The Legacy of Alfred Nobel On 27 November 1895 Alfred Nobel signed his last will in Paris. Play the Blood Typing Game Try to save some patients and learn about human blood types! Unlocking the Secrets of Our Cells Discover the 2012 awarded research on stem cells and cell signalling. Contact E-mail us Press Sitemap A-Z Index Frequently Asked Questions Terms Follow Contact | Press | Sitemap | FAQ | Terms Follow us:
File:MRNA.svg Cancel Edit Delete Preview revert Text of the note (may include Wiki markup) Could not save your note (edit conflict or other problem). Please copy the text in the edit box below and insert it manually by editing this page. Upon submitting the note will be published multi-licensed under the terms of the CC-BY-SA-3.0 license and of the GFDL, versions 1.2, 1.3, or any later version. Add a note Draw a rectangle onto the image above (press the left mouse button, then drag and release). Save To modify annotations, your browser needs to have the XMLHttpRequest object. [[MediaWiki talk:Gadget-ImageAnnotator.js|Adding image note]]$1 [[MediaWiki talk:Gadget-ImageAnnotator.js|Changing image note]]$1 [[MediaWiki talk:Gadget-ImageAnnotator.js|Removing image note]]$1
Cell Models For life all cells have basic needs. Cells have diverged in their structure and function to accommodate these survival requirements. Here are some KEY TERMS to help you think, explore and search for similarities and significant differences that have become the characteristics of eukaryote (animal, plant) and prokaryotic (bacteria) cells. Examples might be searching: eukaryote prokaryote reproduction or animal plant cell energy. Reproduction / cell division Energy trapping, storage and consumption Form / shape / structure Cell specialization Compartmentalization of cell functions Communication within and beyond the cell Cell / organism survival MCAT Biology | Prokaryotic Cells Background Prokaryotic Cell Structure Prokaryotes are simple organisms that contain no membrane bound organelles. These simple organisms are commonly known as bacteria, viruses and bacteriophages. They may also contain plasmids, which is a small ring that contains a few genes that may offer antibacterial resistance. Prokaryotes also have 50s/30s subunit ribosomes and have locomotion through their flagella Prokaryotic Asexual Replication Simple prokaryotic cells such as bacteria and viruses replicate asexually which means that they do not require a partner to make an offspring. Binary Fission Budding Regeneration Parthenogenesis Binary Fission Binary fission is a rapid process of replication that occurs in prokaryotes. Binary fission is a little bit different than mitosis as the separate DNA regions attach to the cell membrane as the cells begin to stretch apart. Budding Budding is a type of replication that produces a daughter cell with an unequal division of cytoplasm. Regeneration Bacteria
Regulation of Gene Activity and Gene Mutations 15.1 Prokaryotic Regulation Bacteria do not require the same enzymes all the time; they produce just those needed at the moment. Francois Jacob and Jacques Monod (1961) proposed the operon model to explain regulation of gene expression in prokaryotes. In the operon model, several genes code for an enzyme in the same metabolic pathway and are located in a sequence on a chromosome; expression of structural genes is controlled by the same regulatory genes. The trp Operon Some operons in E. coli usually exist in the "on" rather than the "off" condition. E. coli produces five enzymes as part of the anabolic pathway to synthesize the amino acid tryptophan. If tryptophan is already present in medium, these enzymes are not needed and the operon is turned off . The regulator codes for a repressor that usually is unable to attach to the operator. The entire unit is called a repressible operon; tryptophan is the corepressor. The lac Operon These three enzymes are encoded by three genes. Carcinogenesis
The most direct way to control the expression of a gene is to regulate its rate of transcription; that is, the rate at which RNA polymerase transcribes the gene into molecules of messenger RNA (mRNA) The Lac operon, an example of a transcriptionally regulated system. The most direct way to control the expression of a gene is to regulate its rate of transcription; that is, the rate at which RNA polymerase transcribes the gene into molecules of messenger RNA (mRNA). E. coli break lactose down using two (there are 3, but our problem set only addressed two) enzymes: beta-galactosidase, which is encoded by the LacZ gene, and permease, which is encoded by the LacY gene. These genes and the regions that regulate them are called the Lac operon. Other important players in the lac operon are: Operator (LacO) the binding site for the repressor Promoter (LacP) the binding site for RNA polymerase Repressor (LacI) the gene encoding for the lac repressor protein- in the absence of lactose the repressor protein binds to the operator and blocks binding of RNA polymerase at promoter The genotypes are written in order of: repressor (i), promoter (p), operator (o), LacZ (z), LacY (y). Lac operon