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The practical component will be done on Monday 2nd March.
The written report will be done entirely during class on Friday 6th March.
This SAC is slightly different in that it is a summary report rather than a practical report. What is the difference you ask? Well, the questions are to do more with enzyme theory, and the link between DNA and proteins, as well as applying your knowledge from the prac you do. There is only a minor reference to the actual catalase prac that you will do on Monday. The practical report you write up relating to the catalse experiment (this is NOT being assessed as part of the SAC) is all that you will be allowed to bring into the SAC on Friday as resource material.
extra copy of the enzyme prac
biol 3 catalase enzyme prac 2009.doc

Enzyme SAC criteria
enzyme_SAC_criteria.gif


enzyme SAC (biochemical pathways)

Concepts you need to know and understand (no pun intended!)
  • enzyme structure
  • role of enzymes in biochemical pathways
  • enzyme theory-"induced fit" and "lock and key"
  • factors affecting enzyme activity and thus reaction rate
  • relationship between enzymes as proteins and DNA sequence

More info

The SAC report is divided into three sections (A, B and C). Questions in:
  • Section A are experimental in nature.
  • Section B focus on the theory and role of enzymes in biochemical pathways in unfamiliar contexts
  • Section C require you to apply your knowledge about the link between DNA and proteins and the field of proteomics


Q. Letter C) for page 21 on newest buiology course notes, is answer: none. If not why? RD
A. Ok this question probably should be put in the faq page, as it is not directly related to the enzyme SAC. But it will do here for now. The answer is NOT none but light intensity. Understanding this reflects quite a deep understanding of graphs and reaction rates. It is about the section between X and Y which is the upward slope of group 2. During this section it is the light intensity that determines the rate of photosynthesis. Another way to look at it is to pick any point on the slope and ask yourself "why isn't the rate any higher?". Answer: because the light intensity is only a certain amount at the point in the graph. If we go to the right and increase the light intensity then so does the raction rate. So this is saying that light intensity is the key factor that limits how high the rate of photosynthesis is. VM

Q. im a bit confused about your second-last dot point above (membrane sac feedback), in relation to the "conclusion" example you gave.... if one would state the GENERAL effect that temperature has on a reaction/process as a conclusion statement (ie. without using data or being specific), then wouldnt that be accepted as a ligitimate 'conclusion'?? if not, then what is "an actual" conclusion about the effect of temperature? - LA
A. If a question asks you to make a conclusion based on the results you must use the results to support your statement. You cannot make a conclusion otherwise. A conclusion in this sense is not an explanation. Not sure if this what you are after. I will talk about a possible answer in class during the enzyme prac. Remind me! VM

Here are my questions (for now): OS

Q. Why are Ribozymes considered to be harmful?
A. Hmmm... I gave you a little bit of info on these. Only recently it was discovered that there were some RNA molecules that acted like enzymes (ie not all enzymes are in fact proteins! there are always exceptions to rules in biology). Ribozymes are really limited to acting only on RNA molecules so they do not catalyse other chemical reactions in cells. As to them being harmful, I am not aware of this. Where did you come across this information. Ribozymes are in fact considered to be essential to life. Anyway, you do not need to worry about any details to do with ribozymes. Just know that a ribozyme is an RNA molecule that can act like an enzyme. VM

Q. What do coenzymes ACTUALLY do?
A. Coenzymes assist chemical reactions to occur. They are involved in biochemical pathways. You have come across examples in respiration and photosynthesis. eg coenzyme A, NAD+ and NADP+. That is all you need to know. VM

Q. Can the reaction rate remain the same for different substrate concentrations if there is a sufficient amount of enzyme concentration to break down the substrate (for all of the concentrations)?
A. Not sure if I am clear on your question here. Do you really mean sufficent amount of enzyme? If so, the answer is NO. Changing substrate concentration will always increase or decrease the reaction rate (depending on whether you are increasing or decreasing substrate concentration) if there is a sufficient amount of enzyme present (ie enzyme concentration is NOT a limiting factor). VM

Q. what EXACTLY is a biomolecule?
A. Any molecule that is prodcued by living organisms. They are organic, small or large. Eg glucose is a biomolecule so is a protein or polysaccharide. The only confusion here is that water is considered a biomolecule because it can be made by living organisms, ie through respiration. VM

Q. If co-enzymes are non-protein organic substances, do we need to classify them or can they even be classified as any specific organic substance?
A. No you do not need to worry about that really. They are organic and that is all you need to worry about. VM

Q. voj, what do you mean by a 'summary report' (rather than a practical report)?? do you mean simply drawing out conclusions (summaries) from the prac, and using them to answer other enzyme-related theory questions? and, in that case, how can we prepare for it, or how can we know that we know what we need to know / think we know.......you know? :) ............ [ by the way, yes i have realised you have stated the difference above, however i still dont QUITE understand how the specific prac we did is relevant to the Qs (on the SAC) ]...
A. How can I explain this. The prac you did is relevant to the SAC report simply because it relates to enzymes, how they work and how you carry out an experiment involving a biochemical reaction to obtain some results. That is it. The summary report is more about asking you a whole variety of questions, some experimental based (in a different context) others to theory and applications of theory. You cannot know what I am going to ask. It's the same for the VCAA exam. You need to be able to understand all the concepts as well as possible.You can prepare for it by doing the specific homework I have set (minimum) and trying to improve your understanding of the different areas I have mentioned above. I am not going to specifically asses you on the prac you did, it is just a resource for you, should you need it. See above, as I have provided more ifo about the SAC. VM

Q. this is to do with enzyme-catalysed reactions being 'reversible' (eg. converting A to B+C, or bonding B+C to make A).. Is the same enzyme used to catalyse both of the reactions? in other words, is the enzyme that's used for A->B+C the same for the enzyme in B+C-->A? and if so, how does that make them 'specific' then?
A. Ok, you have brought up something that we don't really need to worry about in Biology at this level. I don't really want to go into this here, as I may confuse you with my explanation. Those doing Chem will have to learn all about the fact that most reactions are in fact reversible.This is the case in Biology. And yes the same enzyme catalyses the reaction in both directions. All this is to do with the concept of equilibrium (sort of like diffussion and osmosisalways proceeding in a direction so that ultimately the concentrations are equal on both sides of the membrane). The enzyme is still being specific even though it catalyses the reaction in both directions because it is still working on the same substances. So if for example A is converted to B and C, then B and C start to build up in concentration. If B and C hang around (ie they are not used up or converted into other substances) then the reaction will begin to proceed in the opposite direction whereby B and C are converted back to A. VM



hey voj, no ur not dreaming, i am actually posting a question on the wiki.
Q. do competitive inhibitors stay in the enzyme or can they leave the enzym after a while? i know that the shape of the active site of the enzyme is only changed by non-competitve inhibitors, but can enzymes work after an competitve inhibitor leaves it (if it can leave it)???? MG


Welcome to the wonderful world of commenting wiki pages MG, it is us, Joshua and Olivia replying from the gates of heaven. We await your arrival.
Here is your answer from God himself;
"Competitive enzymes will eventually leave the enzyme, after F* up the process for a while, whereas; non-competitive enzymes can be permanently fixed to the enzymes. Yes, enzymes will still interact with substrates after the competitive enzymes leave, as they don't change the active site, just temporarily interfere'.

Hopefully we wont see you for a while yet, enjoy your stay on earth.

By the way, you can play as much soccer as you would like in heaven, as injuries are non-existant.

Over and out.

Fellow angels i would also like to add that competitive inhibitors can also be permanent... for example the the medicine that stops the HIV virus enzyme is a competitive inhibitor as it blocks the active site and it is also permanent :)
much love MW

well well well... mikayla, you are a myth buster...not all angels are such innocent 'air-heads'... but i would love a clarification from your wise wise words.... are you saying that 'Rational Drug Design' (ie. the drugs used to prevent or manage viruses/diseases) is a form of competitive inhibition, and which are drugs that act as permanent competitive inhibitors.?? can this be the case?
and may i also respond to the God(s) above... i believe non-competitive inhibitors are TEMPORARY. - not permanent.! (but correct me please if im wrong missbiology! =))
(yes, from the fadicha angel herself)..


So you all have time for humorous banter on this wikispace, late at night prior to a biol SAC. Well, let me see, (apart from taking thy name in vain!) I am now expecting you all to do extremely well on the SAC. For if you do not, I shall cast down upon you something far worse than Makot Mitzrayim. be׳seder! And it wont be temporary either, it will be PERMANENT! Never over and never out. VM