Jump to content


Senior Members
  • Posts

  • Joined

  • Last visited

Everything posted by Greippi

  1. The gaps are REALLY TINY compared to the cells - because a single molecule compared to a cell is really tiny. So they wouldn't appear as obvious gaps in the diagram. In the case of white blood cells passing through these gaps - obviously the gaps are bigger in this type of vessel, but it is still necessary that the shape of the white blood cell distorts and stretches to squeeze through the gap.
  2. Glad to help A capillary is a tube made up of endothelial cells. The cells make a circle, so the cell goes through the hole, there is no block. Kinda like this cross section:
  3. A capillary is like a vein - basically a tube. The blood cells pass down the tube. The walls of the capillary are only one cell thick (endothelial cells) - which have spaces between them so stuff from the blood diffuses through the holes in the capillary to the cells beyond the capillary (e.g. liver cells). So yes, veins connecting capillaries contain blood cells, they just narrow down in size to become capillaries. A capillary is just big enough for a red blood cell to fit through - but they have to go in single file. Nutrients just diffuse through the spaces between the capillary cells. The spaces are big enough to allow small molecules (and some are large enough for larger proteins to fit through). Nutrients that are specifically for the endothelial cells to function are taken up by the cells of course via various active and passive processes. Hope that makes things a bit clearer. another thing I thought of: during the immune response, certain types of white blood cells pass through the spaces between the endothelial cells of postcapillary venules via a special process.
  4. Normally, blood cells do NOT pass through capillary walls. Capillaries are 'leaky' meaning that plasma and anything dissolved in the plasma will leak through between endothelial cells. Blood cells are just too big to fit. Oxygen, water, and other chemicals pass through the capillary wall. However, some capillaries called sinusoidal capillaries (found in the liver, bone marrow and other places) have larger openings between endothelial cells and can allow white and red blood cells to pass through. So the key is: BETWEEN the endothelial cells, not through the cells.
  5. Hitch Hiker's Guide To The Galaxy "trilogy". Read it at least once a year since I was 9.
  6. I'm Katie Grape. Awesome.
  7. The very definition of "endocrine" means that the chemical produced (usually hormones) travels over a distance via the blood stream to produce an effect elsewhere in the body. For example, the pituitary in the brain produces ADH, which travels via the bloodstream to the kidney's collecting ducts, where it causes increased re absorption of water in to the blood.
  8. In the field of biofuels, photosynthetic organisms are the key. Photosynthetic algae and bacteria only need sunlight, carbon dioxide and water to make biomass. In today's world where "green" issues are high on our agenda, carbon-neutral sources of fuel are extremely desirable. 100 tons of algal biomass fixes about 183 tons of carbon dioxide. The dry weight of some microalgae is more than 80% oil (compare this with less than 5% for soybean, or oil palm). Since the oil yield is so high, to provide the USA with all the biodesel it would need in a year (replacing petroleum derived transport fuel) microalgae would only need 3% of the US cropping area to produce this amount (oil palm would require 61%). This land doesn't even have to be agriculturally productive! Another advantage is that the biomass doubling time of microalgae is only 24 hours. 'Biodiesel from microalgae beats bioethanol' Chisti, Y (2008). Trends in Biotech 26, 126-131.
  9. Where possible, the male should be placed on the left of a mating line. Then children are placed in order of birth.
  10. If you're looking to do a PhD, many PhDs in the science field come with funding. In England it generally doesn't matter where you come from - as long as you're the best person for the "job".
  11. Well, it involves protein interactions.
  12. It's not just evergreen trees. There are a lot of oak trees where I live, and during the summer when they all have leaves the digital signal is adversely affected particularly when it's windy.
  13. If you are absolutely certain that there is no other source of glucuronic acid or hydrogen peroxide I would have thought so. However, I can't really give you a better response because I don't know where this "pale purple colour" is coming from. What IS the purple colour? Do you have an indicator in there? What is it indicating the presence of specifically?
  14. Really scratching the surface here, because "junk" DNA is such a massive field, but I'll attempt to give a basic answer: Junk DNA is a bit of a misnomer these days. Much of the non-coding DNA has a function - including control of transcription and translation of coding genes, as well as spacing. A brief scan of even the Wikipedia article on the subject will give many more functions. The majority rest of the DNA whose function is as yet unknown is not highly conserved - suggesting that it is not part of a major pathway (such as psychic phenomena). For DNA to have a function, it must interact with other molecules. From the sequence of DNA is transcribed RNA which can then go on to be translated in to proteins, or remain as RNA with another specific function. If there was DNA that was used for psychic purposes, it would need to encode some other series of molecules - which surely would have been detected by now due to the sheer amount of study that has been done on the genome/contents of the cell. "Normal" coding DNA encodes proteins, you would have thought that a rogue protein being produced that was not linked to any of the metabolic pathways would have been a cause for much interest. A whole network of proteins that hasn't been discovered yet that is used for psychic phenomena is pretty unlikely don't you think?
  15. Apparently there is nothing unusual about the seismic activity this year. Statistically speaking, it's within the "normal" range.
  16. Considering hydrogen peroxide is highly damaging to our cells, this product can only do more harm than good. We have mechanisms in place to remove reactive oxygen species (ROS) such as this, which can cope with small amounts produced naturally by cells as a byproduct of normal oxygen metabolism. But of there's too much of it around obviously it can't all be "mopped up", and ROS can go around causing damage - a major contributor to the process of ageing. he says that our body does not get enough oxygen, and that our lungs only extract 15% of the oxygen we breath. Sounds like evolution has screwed up and its a good thing this book was written.....lol Indeed. Last time I checked I was still alive.
  17. Endocrine would be hormones. So you're looking at the sex hormones. A little research in to sex hormones should yield results!
  18. How strange, if the flames had merely changed colour it would be more explainable, but since you observed an 8 inch flame, that's weird. The most likely explanation would be some sort of contaminent such as cleaning product in the water. If it was salt water then it would most likely be down to the sodium, even though this sounds a bit strange as I would imagine the concentration of sodium would be very low. However, I have heard of engines that somehow produce superheated steam and can produce an orange flame (presumably this would be combustion of hydrogen) but I have no idea how it works or if it is in fact possible. I would assume that this requires specialised apparatus and I seriously doubt this happened here.
  19. I assume you have a graph featuring a line that starts off as you increase substrate concentration by going up, then curves off until it plateaus. Where the plateau is is where the reaction is going its fastest - the enzyme simply does not "work" any faster no matter how much more substrate you add. I think you might be missing the point of what is happening here. The substrate diffuses in to the active site, the reaction occurs, and the product diffuses out of the active site, leaving the active site free to bind another substrate molecule and catalyse the reaction again. Okay, say you have 10 enzymes. You have 10 active sites available, therefore only 10 molecules of substrate can fit in to the active sites at any one time. You put in 1 molecule of substrate, there are many active sites available so it quickly binds to the enzyme and the reaction is catalysed, the product diffuses out of the active site which is then free to bind another substrate and do the same thing. You put in more substrate molecules and the rate of reaction increases as more product can be made in the set amount of time as there's more substrate available. But then if you add 11 molecules of substrate at once - all 10 sites get filled up and the 11th molecule has to wait its turn. Increasing the substrate concentration further has no effect on speeding things up as ther's no room in the active sites - they have to wait until the site becomes available. An enzyme can only work so fast and the rate of reaction is different for different enzymes (put simply, there's the speed at which the substrate binds to the active site, the time taken to catalyse the reaction, and the speed at which the product moves out of the active site making it free to bind more substrate).
  20. Decimals have a taste. But then colours also have a taste. 5 is red and tastes slightly metallic, slightly of chocolate, but 5.5 is REALLY metallic tasting but the colour isn't so strong. I know what you mean about the layers. The more I think about it, the more complicated it gets. it's really hard to describe things in words too. Multiples of three are yellow. I have problems when people ask me what something tastes like - the other day I was sampling a sauce I made and I said it tasted like "2 octaves higher than middle C on a harpsichord". My year is a ruler mostly stretching away from me but the perspective is all skewed. January and February, although they are closest appear smallest, May and October the biggest. That's the best I can explain it. My number line consists of several curves stretching away from me - so on the left we have 1-100, then next 100-500, then 500-1000 and so on. I find I have an aversion to certain shapes. On their own, I like crop circle arrangements, which are blue, but I do not like curves. A graph with a curve, rather than straight lines, I don't like because it tastes of vegetables that are going off and the sound it makes makes me feel quite unpleasant..hah! I would be interested to know how it affects your life, cos while my "condition" enhances some things, often it is quite opressive and overwhelming.
  21. I have synaesthesia. I could ramble about it for ages, so contact me if you need more info. It's quite interesting how it impacts day to day life as it is easy to get overwhelmed. In brief: - Sound creates colours and landscapes, very occasionally taste. Some music causes this stronger than other types of music. I tend to rate how good music is by how strong the sensations are. Sometimesthis is quite overwhelming because the soundscapes are so powerful I can't think straight when listening to the music. Most of the time this isn't too strong, so I CAN listen to music without being distracted by colour. It's like wearing clothes - you don't feel the clothes against your skin CONSTANTLY, or your brain can block out peripheral sounds that you don't need to hear. - For this reason, I find people's voices very interesting. - Smell has colour. - Taste has sound and colour, this is the strongest synaesthesia "sense" I get. - Touch has a sound and sometimes colour. The touch as sound thing is probably one of the "strongest" sensations. - Days of the week, months, letters, numbers etc have colours this is beyond normal colour associations). For example, Fridays are dark red, Thursdays are green, Tuesdays are blue. January is red. October is brown. The letter J is purple. C is yellow. 12 is dark blue. 80 is Cadbury's purple. 50 is salmon pink. - Time, numbers, letters have a "particular arrangement in space". For numbers, this is stronger than the sense of colour for them. "In synaesthesia, the sensation would be physical, i.e. you would physically see green, rather than be reminded of it." It's quite difficult to describe, as this description implies that it would shroud some of your "normal" vision.
  22. In some cells, cilia can grow from centrioles which play an important part in cell signalling (e.g. platelet derived growth factor).
  23. You could make a broad estimate using the error rate of DNA replication (1 in 50 million possibly, off the top of my head). But of course there are other factors that cause mutations in the genome - for example the incorperation of viral DNA. Smoking one cigarette will cause on average 15 mutations in a lung cell (typically 30,000 mutations are observed in a cancer cell).
  24. If you're querying why it only runs as one band: Correct me if I am wrong, but when you prepare protein for SDS PAGE, are you not merely denaturing the protein (i.e. causing it to lose its structure, but not breaking bonds between consecutive amino acids)? Of course, it depends on how you have prepared the protein before you load it on to the gel, but usually you would expect a protein to run as one band. Breaking disulphide bonds merely breaks down the tertiary structure further and would not break the peptide bonds holding the chain of amino acids together, so it would still run as one band. I think this may be your main issue though: Your peptide is very small. SDS PAGE is not generally used for the analysis of peptides. Very specialised systems are available for larger peptides (greater than 50 residues) , but on a normal SDS gel, the peptides just run at the buffer front - your size of 4kD may just have been the buffer front! Other problems with peptides include poor staining and the fact that they don't fix in the gel. Merged post follows: Consecutive posts mergedAs for your "protein was analysed", what methods were used? The numerical values, are they how many residues actually are in the peptide, or are they the molar ratio results of an amino acid analysis? Once I know this, I can help you a bit more.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.