biol+3+faq(nsfaq)

If you have any questions or are uncertain about anything to do with the course, then this is the place to get help. I will try and respond to your query as soon as possible, although I strongly encourage you all to try and answer each others questions first.

biol 3 faq(nsfaq)1
 * A new faq page has been created so please post questions there from now on.Click link below. **

Q. Very biological of me... what chapters from the text book get covered in semester one?? //A. Hmmm...I will expect the quality of the questions you ask to improve rapidly as we begin our journey this week. To answer, if you look at the front of the text you will see the chapters are organised as Unit 3 (1st semester) area of study 1 and area of study 2 which are the first 9 chapters and then unit 4 starts from chapter 10. VM//

Q. In the biomolecules tile puzzle, a corner of one of the tiles reads 'stack of cisternae'. What is a stack of cisternae? Thanks. //A. This term relates to the golgi apparatus. It is not an important term but if you recall how I tried to explain the golgi as a series of distorted long-balloons, the name given to these is cisternae. VM //

Q: What is the structural difference between a triglyceride and phospholipid molecule? It is the phosphate group (phospholipid) and the third fatty acid (triglyceride)? - OS

A. Olivia i believe you are rather spot on there. a triglyceride is a phosphate group linked to 3 fatty acid chains while a phospholipid is a phosphate group linked to just 2 fatty acid chains. I have not however completed my biology degree yet so if vojtech would like to correct me that would be wonderful. JA

//A. Ok fellow biologists, you have to be careful with your use of words. JA I think you have confused phosphate group with glycerol in your triglyceride explanation. Here is another way to look at it. Both phospholipids and triglycerides have a glycerol backbone but in **phospholipids there are two fatty acid tails and a phosphate group attached** while in **triglycerides there are three fatty acid tails and no phosphate group**. VM //

Q. In terms of DNA and mutations, do the mutations occur in the strand of DNA and then result in an incorrect mRNA strand or do they occur when the mRNA is produced from correct DNA, or both? I'm confused.. //A. Good question. Strictly speaking a mutation is defined as any change in the DNA sequence. Subsequently, this will alter the mRNA that is produced. As far as we are concerned mRNA does not mutate. VM //

Q. Can we get a glossary up for area of study 2? I hope my specific wiki isn't stuffing up but when i put the curser of the line 'area of study 2', no link comes up. //A. No, you have nothing to worry about. It is because there is no link! BUt you could do this yourself you know. All you do is go to "create a new page". Then go back to the page where you want to make a link by editing the page, highlighting the text and clicking on the first earth symbol and chain in the editor bar. Click on the page you want that link to go to. be׳seder VM//

Q.Sorry for ruining your display on this page (//you didn't, cos I moved it to this page //), but i didn't know where else to ask for answers to the homeostasis sheets, as the text book wasnt as useful as we both hoped it would be! lots of love, ss. //A. I will get them up as soon as I can. they will be on the solution page. VM //

Q. (refer to page 42 of workbook) states that nerve cells are undirectional. Which means that they DON'T produce or recieve signals better in one particular direction. However, see as they ONLY receive and send signals in one particular direction, then wouldn't that make them directional not undirectional? o.s. //A. Hmmm... miss biology you are correct in suggesting that there is only one direction that the impulse travels. But the confusion here is because you see but do not OBSERVE! The statement in the book says un**i**directional, meaning exactly what you are saying, in one direction only. VM //
 * Homeostasis:**

//A. Yes, serotonin is a neurotransmitter found in the brain and has an affect on mood (sense of well being). Structurally it is based on one amino acid that has been modified. VM//
 * Q:** Would it be correct to say that an example of a neurotransmitter is serotonin(affects mood)?

<span style="color: rgb(19,22,241);">//A. The pituitary gland is made up of two lobes (sections), one is called the anterior, the other posterior. You do not need to really remember this and it would be ok for you to say that a particular hormone is released from the pituitary gland. So, you do not need to specify, although if you want to be totally accurate you might want to remember. In general hormones are relased from the posterior pituitary. VM//
 * Q**: What is the difference between 'anterior pituitary' and posterior pituitary'? Do we have to know this?

Q. quick question....the fourth activity in the newest set of coarse notes. the table shows that seed A placed on its side will grow roots that will curve downward. i know that if the plant is placed on its side the auxin will fall to the bottom of the stem and cause the plant to grow upwards as the bottom cells are elongated, but i don't understand why the roots grow down?

//<span style="color: rgb(19,22,241);">A. First of all the auxin doesn't fall to the bottom of the stem, it falls to the bottom parts of the root cells (remember they are on their side). As I said in class the key here is to understand that auxin has a different effect on root cells-it inhibits cell elongation in these cells, so the bottom cells in the roots grow slower whereas the top cells grow as normal causing the bend to go downwards. VM //

Q: is condensation polymerisation a form of synethisis for all biomacromolecules? in the course the process is only linked to carbohydrates and protiens. is it referred to as a synthesis? DV

// A. yes it certainly is. Synthesis means creation, so to make the large organic substances, cells rely on the reaction knwon as condensation polymerisation for making polysaccharides, proteins and nucleic acid from their basic building blocks. VM //

Q. I'm trying to look for information regarding the topic 'Applications of Molecular Biology', and i can't find any in the book... EB

// A. Hmmm.. there is no real specialised chapter on this section of the course. This is because applications cover a number of different areas. Rational drug design/proteomics is one area we have already covered. Other examples which we havent done yet will relate to the immune system and things like vaccinations. VM //

1. figure 35 of the Detecting and responding booklet, i can't really interpret it...? 2. what is the difference between a g protein and a 2nd messanger? thanks! E.B

// A. First of all are you sure it is figure 35? Please check this so that I can specifically help you with the diagram. I gather that the section you are refering to is about signal transduction. G proteins and 2nd messenger is confusing. Strictly speaking the g-protein is activated by a signalling molecule binding to a recpetor on the membrane. The activated g-protein then results in the activation of a second messenger system (such as cAMP) that is part of a the signal transduction pathway. It seems VCAA accepts the term g-protein as an example of a second messenger. If you are asked to give an example of a second messenger I think you should use cAMP to be on the safe side. VM //

hey voj, i asked my mom about what happens with the stemcells that they remove and she said that the reason she was given was that if someone has cancer and then are in remission they take the stemcells so that if they get a worse type of cancer that cannot be treated with chemo or radiation they can just kill all their current stemcells and replace them. so i dont think its to do with antibodies, but might be? // This sounds logical to me. We have yet to look at cancer in any detail but you will find that dealing with cancer isn't really to do with the humoral response (and therefore antibodies) but rather the cell-mediated response. VM //

Q. Are the immature lymphocytes produced in the bone marrow a type of white blood cell? // A. Ok but I am going to ask you now, What do you think is a lymphocyte? Answer this question for me below and then I will respond further. VM //

Q. I would probably break the word up and say 'cyte' means cell and 'lymph' refers to the lymphatic system. So a lymphocyte would be a cell belonging to the lymphatic system - a lymph cell. // A. Excellent thinking. The question now is, what is a white blood cell? White blood cells are cells of the immune system. Given the lymphatic system plays a key role in the immune response, lymphocytes are therefore a type of white blood cell. VM //

Q. Can you upload the slideshow of the cell-mediated response? //A.// // Already have done this, the link is on the home page in the "What's new?" section. VM //

Q. Does the non-specific immune system also involve antigen recognition in the second line of defence? // A. Hmmm... not totally sure here. Great question though! My limited understanding is that there is a surface receptor type recognition system used by the "defensive" cells of the 2nd line of defence in detecting pathogens in general BUT it would not be referred to as antigen recognition. Remember, antigens are substances that result in antibodies being produced and this is limited to the specific immune response. This level of detail should not be asked by VCAA. VM //

Q. Do B lymphocytes roam around in the bloodstream and or lymphatic system searching for antigens or are they just situated in the lymph nodes? A. // Hmmm.. good question, I probably haven't made this clear enough. Lymphocytes by definition are cells of the lymphatic system (that is where they form) and primarily reside in the lymphatic tissue (that is where most of them are) but they do travel in the blood as well. That's why leukocytes are also called white blood cells and lymphocytes are a type of leukocyte. VM //

Q. Just to clarify... do both B cells and Helper T cells get stimulated after coming into contact with foreign antigens and do B cells try and attach to antigens that are attached to non self cells (could be a pathogen) in the humoral response? A. // Yes they do, in a way. But the key point is that Helper Tcells are important in activating a Bcell so that it clones itself and differentiates into plasma and memory cells. I suppose B cells could bind to an antigen that is actually on the surface of a pathogen. However, this won't destroy the pathogen, nor is it the most important interaction as I have mentioned in the previous sentence. VM //

Q. If solution 1 is deemed to be hypotonic or hypertonic to solution 2, is that always a reference to the water concentration or can it be the solute concentration. I mean, can i assume that hypotonic means less free water molecules than the other or should i think it means there is less solute than the other solution? A. //The way I read your example is that solution 1 is being compared to solution 2. So, if solution 1 is hypotonic it means less solute conc (OR more free water molecules) COMPARED to solution 2. If solution 1 is hypertonic it means more solute concentration (OR less free water molecules) COMPARED to solution 2. You must be clear on what is the reference solution. As we are dealing mostly with cells, we often refer to the extracellular environment as being either isotonic, hypertonic or hypotonic (ie compared to the cytosol within the cell). So my question to you now is which direction does water travel if a cell is placed in a hypertonic solution? You must be clear on this. VM//

A: water moves out of the cell. so basically you are saying hypertonic and hypotonic is a reference to both water and solute and not one more than the other. //yep that is the way to look at it, it refers to the solution in general (which contains both water and solute). VM//