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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Biology => Topic started by: Snorlax on February 27, 2013, 10:05:19 pm

Title: Second Unit 3 SAC?
Post by: Snorlax on February 27, 2013, 10:05:19 pm
Just because the first one was useful to me/others :)
So, what are your schools doing?
-mines going to be quite similar to our first SAC: A practical + report + Application q's! - on enzymes
Title: Re: Second Unit 3 SAC?
Post by: pi on February 27, 2013, 10:51:22 pm
I think I did something on amylase and liver pieces back in the day :)
Title: Re: Second Unit 3 SAC?
Post by: Jayward on February 27, 2013, 10:58:12 pm
I think I did something on amylase and liver pieces back in the day :)

i got H2O2 on my hand during this sac -.-
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 01, 2013, 07:23:38 pm
i got H2O2 on my hand during this sac -.-
All i hear whenever talking about enzymes are Hydrogen Peroxide reactions! bahhh!

So, at the moment not sure about the practical we'll be doing...We always get informed on the day... SURPRISES. YAY.
Title: Re: Second Unit 3 SAC?
Post by: Bad Student on March 01, 2013, 07:48:36 pm
I did mine today on diastase and starch.
Title: Re: Second Unit 3 SAC?
Post by: Daenerys Targaryen on March 01, 2013, 08:32:35 pm
I had 4 kinds of liver, control, grounded, diced, and boiled.

and tested which was most effective.

covers surface area to volume ratios
denaturing of enzymes
Title: Re: Second Unit 3 SAC?
Post by: Smiley_ on March 01, 2013, 09:31:04 pm
I had 4 kinds of liver, control, grounded, diced, and boiled.

and tested which was most effective.

covers surface area to volume ratios
denaturing of enzymes

What kind of questions did you have ?


What othet types of things could we do ?
Title: Re: Second Unit 3 SAC?
Post by: Daenerys Targaryen on March 01, 2013, 09:40:14 pm
This refering to SA:V ; which was best at making H2O2
Why was the boiled one crap at making H2O2 (or whatever the chemical was)
What does this suggest about the enzymes at high pH and low pH?
(we also tested each of them with different pH's)
Enzymes at different temperatures?
Title: Re: Second Unit 3 SAC?
Post by: Stick on March 01, 2013, 10:51:48 pm
My second SAC is also an experiment with a test/write-up part to be completed in the next lesson, just like my first SAC. This SAC will cover enzymes, but I am not aware of the specifics of the practical component.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 02, 2013, 02:03:56 pm
Quick question:
Is the lock-and-key model only for catabolic/exergonic reactions?
While the induced-fit model is for the anabolic/endogonic reactions?

Also, When talking about enzyme/substrate concentration its talking about the quantity/abundance of them, right?
Title: Re: Second Unit 3 SAC?
Post by: Bad Student on March 02, 2013, 02:11:08 pm
Quick question:
Is the lock-and-key model only for catabolic/exergonic reactions?
While the induced-fit model is for the anabolic/endogonic reactions?

Both models are used to explain both types of reactions. The difference is that the lock and key model is an old, out of date explanation of how enzymes work while the induced fit model is the newer, currently supported model.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 02, 2013, 02:15:24 pm
Both models are used to explain both types of reactions. The difference is that the lock and key model is an old, out of date explanation of how enzymes work while the induced fit model is the newer, currently supported model.
So the induced-fit model can be catabolic?
So a product can bind to the enzyme, then break up releasing energy?
Title: Re: Second Unit 3 SAC?
Post by: Stick on March 02, 2013, 02:38:59 pm
Both models are used to explain both types of reactions. The difference is that the lock and key model is an old, out of date explanation of how enzymes work while the induced fit model is the newer, currently supported model.

Careful with your wording there - neither model hasn't been proven for sure yet. While I (and many others) would agree that the induced fit model does make more sense, you can't just say that it makes the first explanation incorrect.
Title: Re: Second Unit 3 SAC?
Post by: Bad Student on March 02, 2013, 03:32:55 pm
Careful with your wording there - neither model hasn't been proven for sure yet. While I (and many others) would agree that the induced fit model does make more sense, you can't just say that it makes the first explanation incorrect.

I didn't explicitly state that the lock and key model was incorrect. Being old and out of date doesn't make it incorrect.

A good example of something which is old and out of date is Newton's theory of gravitation. Einstein's general theory of relativity has superceded Newton's theory but it hasn't made it incorrect.
Title: Re: Second Unit 3 SAC?
Post by: Smiley_ on March 02, 2013, 09:02:01 pm
so enzymes only speed up reactions?
ei the  reaction would take place naturally the enzymes just make it happen quicker?
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 02, 2013, 09:54:37 pm
so enzymes only speed up reactions?
ei the  reaction would take place naturally the enzymes just make it happen quicker?
But enzymes are essential. They will take play naturally - but that would be useless, and we would die.
So to answer your question; yes, the reactions would still take place.
Title: Re: Second Unit 3 SAC?
Post by: Stick on March 02, 2013, 10:25:42 pm
so enzymes only speed up reactions?
ei the  reaction would take place naturally the enzymes just make it happen quicker?

Again, be careful. If enzymes were not present in living organisms, the metabolic reactions would not occur at a rate which would sustain life.
Title: Re: Second Unit 3 SAC?
Post by: Smiley_ on March 03, 2013, 04:31:43 pm
Again, be careful. If enzymes were not present in living organisms, the metabolic reactions would not occur at a rate which would sustain life.

thanks

could you explain this a little further ?
Title: Re: Second Unit 3 SAC?
Post by: psyxwar on March 03, 2013, 04:43:58 pm
thanks

could you explain this a little further ?
Well, think about it this way -- to sustain our lives, chemical reactions can't take millions of years to happen because by that point we'd be dead. Enzymes lower the activation energy for a reaction and by extension, speed it up so they can happen at a rate that is able to sustain our lives (eg. digestion is catalysed by enzymes)
Title: Re: Second Unit 3 SAC?
Post by: Smiley_ on March 03, 2013, 04:51:18 pm
Well, think about it this way -- to sustain our lives, chemical reactions can't take millions of years to happen because by that point we'd be dead. Enzymes lower the activation energy for a reaction and by extension, speed it up so they can happen at a rate that is able to sustain our lives (eg. digestion is catalysed by enzymes)

so enzymes dont make the reactions happen
they just speed them up!
Title: Re: Second Unit 3 SAC?
Post by: psyxwar on March 03, 2013, 05:04:49 pm
so enzymes dont make the reactions happen
they just speed them up!
Yup, that's the job of a catalyst!
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 03, 2013, 05:05:48 pm
so enzymes dont make the reactions happen
they just speed them up!

Yeah so enzymes decrease the activation energy required for that process to take place, and by doing so, increase the rate of the metabolic reaction in order so sustain life + maintain the effective functioning of an organism :)
Title: Re: Second Unit 3 SAC?
Post by: Stick on March 03, 2013, 08:25:21 pm
thanks

could you explain this a little further ?

Remember, organisms cannot increase the rate of metabolic reactions by increasing temperature, concentration or surface area to volume ratio.
Title: Re: Second Unit 3 SAC?
Post by: Bad Student on March 03, 2013, 08:58:12 pm
Remember, organisms cannot increase the rate of metabolic reactions by increasing temperature, concentration or surface area to volume ratio.

Organisms do have some degree of control over the concentration of certain substances. For example, the compartments in mitochondria can control the amount of enzymes needed in aerobic respiration.
Title: Re: Second Unit 3 SAC?
Post by: Smiley_ on March 05, 2013, 10:29:38 am
 :)
Title: Re: Second Unit 3 SAC?
Post by: Smiley_ on March 05, 2013, 05:26:15 pm
:)


worked out my question
 but is amylase produced in the mouth and  pancreas?
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 05, 2013, 05:27:54 pm

worked out my question
 but is amylase produced in the mouth and  pancreas?

Wouldn't anylase be synthesised in salivary gland cells? Because the amylase enzyme is found in saliva..
Title: Re: Second Unit 3 SAC?
Post by: Scooby on March 05, 2013, 05:29:12 pm
Remember, organisms cannot increase the rate of metabolic reactions by increasing temperature, concentration or surface area to volume ratio.

I wouldn't be so sure about that  :P
Title: Re: Second Unit 3 SAC?
Post by: Scooby on March 05, 2013, 05:30:45 pm
Wouldn't anylase be synthesised in salivary gland cells? Because the amylase enzyme is found in saliva..

Yup, amylase is produced by the salivary glands and the pancreas
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 06, 2013, 08:30:14 pm
I had 4 kinds of liver, control, grounded, diced, and boiled.

and tested which was most effective.

covers surface area to volume ratios
denaturing of enzymes
is the grounded liver and the liver cube representing SA:V?
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 06, 2013, 08:40:23 pm
is the grounded liver and the liver cube representing SA:V?

Probably that the testtube with grounded liver would have a greater rate of  enzyme activity than the cubed liver because the SA:V ratio of grounded liver > SA:V ratio of cubed liver.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 06, 2013, 08:55:30 pm
Probably that the testtube with grounded liver would have a greater rate of  enzyme activity than the cubed liver because the SA:V ratio of grounded liver > SA:V ratio of cubed liver.
when the liver is grounded, wouldnt the bonds in the enzymes/proteins be broken, and so denture?  or is the grounded liver just to see if SA:V affects the reaction?
Title: Re: Second Unit 3 SAC?
Post by: Bad Student on March 06, 2013, 08:58:20 pm
when the liver is grounded, wouldnt the bonds in the enzymes/proteins be broken, and so denture?  or is the grounded liver just to see if SA:V affects the reaction?

No, grinding the liver won't do anything to the proteins in the same way that cutting a piece of paper doesn't cause nuclear fission.
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 06, 2013, 08:59:08 pm
when the liver is grounded, wouldnt the bonds in the enzymes/proteins be broken, and so denture?  or is the grounded liver just to see if SA:V affects the reaction?

I think its only to investigate SA:V ratio :)
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 07, 2013, 07:08:24 pm
When high temperates denature enzymes, which bonds that determine the 3-D shape of proteins break? The hydrogen bonds, ionic bonds or the disulfide bridges? Or all 3?
Title: Re: Second Unit 3 SAC?
Post by: Daenerys Targaryen on March 07, 2013, 08:04:53 pm
Usually hydrogen bonds ( ithink) because they are the weakest. So they generally break first
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 07, 2013, 09:53:12 pm
When high temperates denature enzymes, which bonds that determine the 3-D shape of proteins break? The hydrogen bonds, ionic bonds or the disulfide bridges? Or all 3?

Disulfide bridges + ionic bonds are relatively strong, but denaturation would definitely disrupt the hydrogen bonds between hudrophobic and hydrophilic R-variable groups when investigating the tertiary structure of the enzyme :) 
Title: Re: Second Unit 3 SAC?
Post by: Bad Student on March 07, 2013, 09:57:52 pm
As the temperature increases, the bonds would break in order from weakest to strongest.
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 07, 2013, 10:49:56 pm
As the temperature increases, the bonds would break in order from weakest to strongest.

(1) Hydrogen Bonds
(2) Ionic Bonds
(3) Disulfide Bridges
Title: Re: Second Unit 3 SAC?
Post by: Stick on March 08, 2013, 07:18:06 pm
I had 4 kinds of liver, control, grounded, diced, and boiled.

and tested which was most effective.

covers surface area to volume ratios
denaturing of enzymes

Ended up doing the same prac. Unfortunately, there were a lot of experimental design questions, which are not my forte... I think I still I did alright, however. :)
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 08, 2013, 11:02:24 pm
Ended up doing the same prac. Unfortunately, there were a lot of experimental design questions, which are not my forte... I think I still I did alright, however. :)
good luck.
what do you meN experimental design questions?
Title: Re: Second Unit 3 SAC?
Post by: psyxwar on March 08, 2013, 11:03:56 pm
good luck.
what do you meN experimental design questions?
Questions on hypotheses, controls, variables, potential errors in the experiment, etc.
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 11, 2013, 08:49:28 am
good luck.
what do you meN experimental design questions?

If you were asked to design an experiment in the exam, you'd have to include three main areas that encapsulate all of what psyxwr has mentioned, into these three headings:
(a) Hypothesis
(b) Method - includes control of variables, introducing materials/organisms.
(c) Findings that support/negate your proposed hypothesis.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 01:48:58 pm
If you were asked to design an experiment in the exam, you'd have to include three main areas that encapsulate all of what psyxwr has mentioned, into these three headings:
(a) Hypothesis
(b) Method - includes control of variables, introducing materials/organisms.
(c) Findings that support/negate your proposed hypothesis.
Ahh got it.
Our 2nd SAC now only consists of Results (10marks) and Application Questions (40marks).
Damn happy that i don't need to focus on the experimental design like my last SAC...
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 04:58:19 pm
I'v got a few question:
How is the active site of an enzyme formed?
Also, a cofacotor is a coenzyme, right?
could someone sum up the main points of the two?
thanks.
Title: Re: Second Unit 3 SAC?
Post by: Daenerys Targaryen on March 11, 2013, 05:05:32 pm
I thought coenzymes were the protein kinda ones and cofactor the non protein
Correct if im wrong
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 11, 2013, 05:07:21 pm
I'v got a few question:
How is the active site of an enzyme formed?
Also, a cofacotor is a coenzyme, right?
could someone sum up the main points of the two?
thanks.

The active site of an enzyme is formed by its tertiary structure; you see, all the R-variable groups of amino acids are either hydrophobic, hydrophilic, positively charged or negatively charged due to their molecular make up. Positively charged R-variable groups are joined to Negatively charged R-variable groups along a polypeptide chain by ionic bonds, polar R-variable groups are joined to other polar R-variable groups by hydrogen bonds and non-polar R-variable groups join to non-polar R-variable groups by hydrogen bonds. Cysteine amino acids are joined to each other by disulfide bridges. So when all of these R-variable groups join together by means of hydrogen bonds, ionic bonds and disulfide bridges, an active site is formed that allows the enzyme to complement its substrate and catalyse the reaction.

Cofactors are inorganic molecules that assist enzyme activity, whereas coenzymes are obviously organic non-protein compounds that assist enzymes is catalysing the catabolism (break down of substances) or anabolism (build up of compounds) of a particular substrate. They affect enzyme activity in the the presence of cofactors and coenzymes will increase the rate of enzymatic activity!

I hope that it sums up a little of what you have queries regarding :D
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 05:13:10 pm
I thought coenzymes were the protein kinda ones and cofactor the non protein
Correct if im wrong
Now I'm really confused.
Textbook says: *Cofactors are small inorganic substances
*coenzymes are NON-protein organic substances required for enzyme activity
Title: Re: Second Unit 3 SAC?
Post by: Yacoubb on March 11, 2013, 05:14:18 pm
Now I'm really confused.
Textbook says: *Cofactors are small inorganic substances
*coenzymes are NON-protein organic substances required for enzyme activity

That's right :) Don't be confused lol!
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 05:21:13 pm
so Cofactors are coenzymes. right.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 05:27:35 pm
The active site of an enzyme is formed by its tertiary structure; you see, all the R-variable groups of amino acids are either hydrophobic, hydrophilic, positively charged or negatively charged due to their molecular make up. Positively charged R-variable groups are joined to Negatively charged R-variable groups along a polypeptide chain by ionic bonds, polar R-variable groups are joined to other polar R-variable groups by hydrogen bonds and non-polar R-variable groups join to non-polar R-variable groups by hydrogen bonds. Cysteine amino acids are joined to each other by disulfide bridges. So when all of these R-variable groups join together by means of hydrogen bonds, ionic bonds and disulfide bridges, an active site is formed that allows the enzyme to complement its substrate and catalyse the reaction.

Cofactors are inorganic molecules that assist enzyme activity, whereas coenzymes are obviously organic non-protein compounds that assist enzymes is catalysing the catabolism (break down of substances) or anabolism (build up of compounds) of a particular substrate. They affect enzyme activity in the the presence of cofactors and coenzymes will increase the rate of enzymatic activity!

I hope that it sums up a little of what you have queries regarding :D

thanks for that detailed answer.
Although I think I answered my own question :)
-on a side note to the forming of the active site, the B-sheets and random loops often form the active site due to them being less 'rigid' than the a-helices.
Title: Re: Second Unit 3 SAC?
Post by: Stick on March 11, 2013, 06:12:44 pm
so Cofactors are coenzymes. right.


No, it doesn't work like that.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 06:20:49 pm
No, it doesn't work like that.
Yeah wait..
cofactors-inorganic
coenzymes-organic but not proteins.
it that the main point to distinguish the two?
Additional info would help.
Title: Re: Second Unit 3 SAC?
Post by: Ancora_Imparo on March 11, 2013, 06:24:49 pm
Coenzymes are small, organic, non-protein molecules, such as vitamins, that carry chemical groups between enzymes. However, they are not considered part of an enzyme's structure. Cofactors are non-protein chemical compounds that are bound (either tightly, as in prosthetic groups; or loosely, as in coenzymes) to an enzyme and is required for catalysis. A cofactor can be a coenzyme or a prosthetic group.
Title: Re: Second Unit 3 SAC?
Post by: Snorlax on March 11, 2013, 08:16:32 pm
Thanks for your inputs.
I'm being a pain in the arse today, but it feels like I know, but don't know a lot on enzymes...weird..
Another question: How do you illustrate/graph the activation energy of exergonic and endergonic reactions?
could someone link me on what it looks like?
thanks a heap.
Title: Re: Second Unit 3 SAC?
Post by: psyxwar on March 11, 2013, 09:05:38 pm
Coenzymes are small, organic, non-protein molecules, such as vitamins, that carry chemical groups between enzymes. However, they are not considered part of an enzyme's structure. Cofactors are non-protein chemical compounds that are bound (either tightly, as in prosthetic groups; or loosely, as in coenzymes) to an enzyme and is required for catalysis. A cofactor can be a coenzyme or a prosthetic group.
This. Cofactors tend to be used up in the process of assisting the enzyme (for example, ATP -> ADP + Pi) meaning it needs to be replaced, whereas prosthetic groups are tightly bound and are not used up in the reaction.