scilearner

Hello everyone,

Ok generally what do they mean when they say vasodilation in periphery lead to reduction in blood pressure? Do I have to think of this as expanding the size of a fluid filled container so less fluid splashes againts the walls reducing pressure. Or do I have to think of this like a circuit where decreasing the resistane of a resistor results in decreased pressure just upstream of that resistor. Thank you

Hello everyone,

Ok I know the cytoskeleton of a cell are proteins and they maintain the structure of the cell. I have an idea what it is but can anyone explain it simply. I just want to see if what I understood is correct. For example if I think of it a skeleton and muscle as phospholipid membrane. Does the phospholipid membrane follow the shape of the cytoskeleton. Thanks

Hello everyone,

This is a DIT molecule.

http://www.ebi.ac.uk/chebi/displayImage.do?defaultImage=true&imageIndex=0&chebiId=15768

Now the book says there is a coupling reaction DIT + DIT ----> gives T4 molecule or tyroxine hormone

Now this is how T4 looks like

http://www.speciation.net/Public/Data/sp/Image/thyroxine.gif

I don't understand how you can get this when there is a addition reaction between these two. Does coupling mean something else. Thank you

I don't know why but it says pictures are not allowed in this board.

Hello everyone,

I just read that vitamin D increases the activity of osteoblasts and osteoclasts (secondary effect). Why does vitamin D increase the activity of osteoblasts if it is trying to increase serum calcium levels? Also bone matrix is made up of type 2 collagen but osteoblasts secrete type 1 collagen. Why is that? Thanks

Hello everyone,

I don't understand nutrition topic in biochemistry. I think you need to have lots of questions to understand it. I don't have any. Can anyone tell me where I can find a site with questions on this. Calculate BMR, protein intake, fat intake, daily expenditure blah blah. Thanks

Hello everyone,

I have a quick question. Ok the endoneurium is a layer of delicate connective tissue that encloses the myelin sheath of a nerve fiber within a fasciculus. Now my question is supporting cells of the nervous system like glial cells usually connect two nerve fibres together, so do they lie outside the endoneurium? Thanks

Thanks skeptic. I don't know I have really gone blank and totally confused. So in this solution there are equal amount of base and acid. So how can you just measure the concentration of H+ and say the solution is acidic, don't you have to take account how much base is there in the solution. If there is equal amount of acid and base in a solution shouldn't it be neutral. I know I have some major misunderstanding. Thanks

Hello everyone,

C02 + H20 <---> H+ + HCO3-

Now in respiratory acidosis. You breathe slowly retaining more carbon dioxide. Ok this would shift the reaction to the right but how does it raise the PH. HCO3- also raised the same amount. Thank you

Thanks for all the replies.They were all very helpful I understand now,this is not a string force, this is gravity and free fall occurs.

In the early stages the cell grows and stores up energy and building materials plus it begins to build some key structures used in the process then the DNA is duplicated then spits/separates during mitosis and then immediately following that during cytokinesis the nuclei and the balance of the organelles and membranes are duplicated and then the cell divides.

Thanks I oversaw the cell growing bit. Now it makes sense. Thanks

Hello everyone,

Ok so I read that the reason they are in free fall is because they are going in a circle like this , and the earth curves away from them at the same time or something, could anyone explain it to me simply. Also why don't astraunauts get pushed to the periphery of the space ship by the centrifugal force?They are not wearing belts right, do they I don't know? Thanks

Hello everyone,

When a cell divide, do the organalles divide, or does DNA divide first, and using that DNA information new cells synthesize organalles. Thanks

Thanks for all the replies Yes I really did make a meal out of the numbers.

Hello everyone,

My biochemistry book just says there are 20 amino acids that are essential and not synthesizd by the body. Then it doesn't say how other amino acids are synthesized. My guess is they are synthesized from transamination reactions of essential amino acids. Does that mean if you don't get 20 essential amino acids you would not have the rest either. Thanks

Thanks

Hello everyone,

Quick question. I can understand proteins are needed to make everything in the cell, so if you inhibit bacterial protein synthesis, cell division can not occur. However my question is does the DNA replicate and divide, and then the cell can not make other things they want so cell division stops, or it stops before this? For DNA replication you need DNA polymerase, so is this not synthesized if you inhibit bacterial synthesis. Basically just tell me plainly why inhibition of protein biosynthesis in bacteria inhibit bacterial cell divison? Thank you

scilearner, forgive me if I am wrong, but this sounds like a homework. Therefore I will be diplomatic and point you towards two presentations:

 

This one as a simple animation to recap on simple points:

Kidney Animation

 

and then this PowerPoint for further notes and explanation.

More detail

 

 

If you need further help then come back to raise specific issues.

I understand your point but this isn't homework. I'll check your links anyway. Thanks for them

Hello everyone,

This is what my lecture note is saying about osmotic diuresis.

Water retention in tubules-----> decreased sodium concentration in tubules----> increased concentration gradient of sodium--->sodium pushing limit reached----->decreased sodium absorption---->increased sodium in tubule----> more water retention in tubule

Ok I understand the first 2 points but then how does the concentration gradient of sodium suddenly increase and what is meant by sodium pushing limit reached. Sodium carriers saturated? Please explain to me if you understand this. Thank you

WOW this is the first time I have accepted change as good (when it comes to something we have used to, getting changed) It is funny I actually like the new site better. Well done for everyone involved in this

Thanks Physics fan, that was quite a good answer.

Hello everyone,

I'm getting the feeling I have not understood osmosis all this time even though I thought I did. So if 2 solutions are separated by a water permeable membrane, and one solution has less solutes than the other, water would move to less concentrated area right. Now why does this occur. In the region where there are more solutes are their polar bonds between water and solutes restricting the movement of water molecules in that region, does this create free space for water from high concentration area to move in? If there is more water in one area I can understand how it would diffuse to the less water area but if I consider the whole thing as particles, if both sides have same amount of particles why would anything diffuse to the other side. I mean first side has more water+less solutes and other side less water+more solutes, so particles in both sides are similar so where is the free space for water to diffuse.Sorry if I made a mess of this. Thanks

Hello everyone,

I understand that countercurrent multiplier makes the area around medulla hypertonic, so water can go out of collecting duct. When I checked the function of countercurrent exchanger it was to kep this concentration gradient intact. I looked at the solutes movement in countercurrent exchanger but I don't understand how it keeps this intact or why it it nessecary at all. I understand countercurrent multiplier, and isn't that enough. Could anyone please help. Thanks

Hello everyone,

I have a quick clarification. Enzymes are not consumed in the reaction but cofactor like NAD+ is consumed in reaction right. So does NAD+ first bind to the enzyme and then get reduced in certain reactions? Thanks

Hello everyone,

Why is that when denature protein you can't get it back to orginal shape. Practically it is obvious that when you burn something it is not going to come back for original shape but what is the chemical basis behind this. Are molecules loss or, heat loss or why is it this so. Why does extreme cooling can not get it back to orginal shape. Thanks

Thought this could not get any worse, but it can

Now I realized each capillary is covered by a basal lamina, now how do the molecules pass through this after they pass through the pores?