Key questions: (No specific assignments for this short unit. Each question is up for grabs.)
HELLO HELLO HELLO . IF YOU MAKE A CHANGE TO A QUESTION WRITE THE WORD CHANGE AFTER THE NUMBER FOR THE QUESTION. THIS WILL HELP ME SAVE TIME CHECKING YOUR ANWERS.
1. How does the lac operon work? How does it allow for "intelligent decision-making"? BOTH DONE
The Lac Operon functions with the purpose to produce enzymes that are necessary to break down lactose for energy. A represser's job as a protein is one that blocks RNA polymerase from reading the 3 genes by bonding to the sense strand at the operator site. When lactose is not present the represser will be on the lac operon, hereby turning the gene "off". When lactose and glucose are both present, First the glucose will be broken down, because it is a better sugar. But when it runs out, the bacteria, for example E.coli, without thinking, will begin reading genes on the lac operon. Such is done so by lactose being an inducer to remove the repressor off of the operator site. Intelligent decision making can also be seen after this process as well. When glucose is absent a CAP complex will bind to the CAP site and give the RNA polymerase the "kick" it needs to start reading by bending the DNA a certain way, so the RNA polymerase can bond to the promoter side, thus working as an activator. To conclude, the prokaryote bacteria will ask two questions…#1 is lactose present and #2 is glucose present, these questions allow the lac operon for intelligent decision making.
2nd answer:The lac operon can be called a two-switch system because it asks to questions: Is lactose present? Is glucose present? With those two questions it is able to make intelligent decisions to either turn on or off the genes on the DNA sense strand, even though this system is only in bacteria. The main function of the lac operon is to control genes that produce enzymes that are necessary for the breaking down of lactose in order to get energy, or ATP. When lactose is present, E. coli makes the necessary enzymes to absorb it and use it for energy; however, when it is not present, it does not waste energy making enzymes. At the operator site is where the repressor protein binds to and it determines whether or not RNA polymerase can attach to the promoter site and carry out transcription on the genes. In order to get the repressor off the operator site, lactose is used as an inducer. Lactose then bonds to the repressor in order to remove it because it changes the shape of the repressor. It makes the repressor unable to bind to the operator site. Therefore, when lactose is present the gene is turned “on” because the repressor is no longer blocking the way of the RNA polymerase, but only if the CAP is attached to the DNA as well. At the CAP site is where the CAP complex binds to and when this is on that means there is no glucose present (they have an inverse relationship). Without the CAP, the genes would not be transcribed because the RNA polymerase would not fit correctly on the promoter site to then continue transcribing the genes.
2. How does the trp operon differ from the lac operon? DONE
Operons are the DNA units involved in regulating transcription to turn a gene on or off. There are 2 different kinds: the lac operon and the trp operon. The lac operon controls genes that produce enzymes specifically designed to break down lactose to provide energy. When lactose is present, it bonds to the repressor, altering it's shape so it is removed from the operator site and allows transcription to occur in order to produce the enzymes. The trp operon works the opposite way. It produces enzymes that make tryptophan. The tryptophan bonds to the repressor and changes it's shape so it bonds at the operator site to stop transcription, since it's not necessary to make tryptophan. When it runs out, the repressor comes off and transcription begins again.
3. Why are the following words good choices for what they stand for?
“promoter”: A site in a DNA molecule at which RNA polymerase and transcription factors TRANSCRIPTION FACTORS DO NOT BOND TO THE PROMOTER bind to initiate (or promote) transcription of specific genes to mRNA.
2ND ANSWER:
"Promoter": A site on the DNA strand, more specifically the operon portion, and even more specifically in the promoter site. Here RNA polymerase is created RNA POLYMERASE "WORKS" HERE, BUT IT IS NOT CREATED HERE, and it either bonds or does not bond here depending on the presence of lactose.
THIS NEXT SENTENCE, ALONE, WOULD BE A GOOD ANSWER. BUT THE ISSUES I'VE HIGHLIGHTED EARLIER IN BOTH ANSWERS HAVE UNCOVERED MISUNDERSTANDINGS THAT YOU MUST DEAL WITH. The promoter is where the process of transcription begins, which directly correlates to the name promoter because this is where transcription, begins, or is "promoted".
“inducer”: An agent capable of activating specific genes. A molecule that inhibits the action of the repressor of an operon, preventing it from freely binding with the operator gene and disabling its function. It “induces” the repressor to do what it wants I BELIEVE THAT THE "INDUCTION" IS REFERRING TO TURNING ON THE GENE, AND NOT CHANGING THE BEHAVIOR OF THE REPRSSOR rather than what it would naturally do.
DONE "repressor": A protein that binds to an operator of a gene preventing, or repressing, the transcription of the gene. The binding affinity of repressors for the operator may be affected by other molecules. Inducers bind to repressors and decrease their binding to the operator, while co repressors increase the binding.
DONE "operator": In the case of the lac operon, it is the site where the repressor bonds, when the repressor is released, it allows the RNA polymerase to "operate".
DONE “activator”: the CAP is a type of activator because it bends the DNA in such a way that the RNA Polymerase can bond at the promoter site, thus "activating" the RNA polymerase to read the gene.
DONE "corepressor": a molecule that is capable of combining with a specific repressor molecule and activating it, thereby blocking gene transcription. Just like a “co-captain” or “co-host” the co repressor works as a partner with the repressor helping it to inhibit transcription.
4. What terminology is used to describe cancer? THE ONLY PROBLEM IS THAT A TUMOR ISN'T CONSIDERED CANCEROUS UNTIL IT STARTS TO SPREAD AND INVADE OTHER TISSUES. HOW ABOUT STARTING WITH THIS: Tumors begin whe one cell muates and begins to divide out of control, which is called…..(CONTINUE FROM THERE, EDITING YOUR ANSWER IN SUCH A WAY TO TAKE THIS CHANGE INTO CONSIDERATION) CHANGE.
Cancer begins when one cell becomes cancerous, which is caused by a mutagen called carcinogen, which mutates the oncogene. An oncogene is a gene that when mutated can cause cancer. If the cell avoids destruction, it begins dividing uncontrollably and forms a mass of cancerous cells called a tumor. If the cells remain at only the original site, the tumor is benign. However, if they spread to different tissues and parts of the body the tumor is called a malignant tumor. The process of this spreading of the disease is called metastasis.
