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Poet

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Re: VCE Biology Question Thread
« Reply #9900 on: February 18, 2018, 02:50:28 pm »
0
Hi again, (I feel like I'm on this thread a lot, lol)
I have a question on some text from my booklet:

"There are about 20 common amino acids, all but one of which have a structure based on a single atom of carbon, to which is attached four different atoms or groups of atoms:
- A hydrogen atom.
- An amine group (NH2).
- A carboxyl group (COOH).
- A variable group. (Called here an R-group)."

I was just wondering about the R group (variable group??) In proteins. What are they? What do they do? I'm really, really confused about proteins. Which in turn is confusing everything else in this AOS.
The booklet I have explains the variable group (called here the R-group) as "the varying chemical structure and properties of the R-group that make the amino acids different from one another".
Can someone explain what the heck that means in layman's terms, please? Does it even make sense? Can you guys get me some examples? (Simple ones, because I am a thiiiick human. Sometimes I question WHY I DO BIOLOGY AT ALL, honestly.) >:( >:( >:( >:(

((I apologise for my absolute fury, but I've been struggling with this concept for two weeks, and I just cannot seem to grasp it!!  :'())
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plsbegentle

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Re: VCE Biology Question Thread
« Reply #9901 on: February 18, 2018, 03:27:37 pm »
+2
Hi again, (I feel like I'm on this thread a lot, lol)
I have a question on some text from my booklet:

"There are about 20 common amino acids, all but one of which have a structure based on a single atom of carbon, to which is attached four different atoms or groups of atoms:
- A hydrogen atom.
- An amine group (NH2).
- A carboxyl group (COOH).
- A variable group. (Called here an R-group)."

I was just wondering about the R group (variable group??) In proteins. What are they? What do they do? I'm really, really confused about proteins. Which in turn is confusing everything else in this AOS.
The booklet I have explains the variable group (called here the R-group) as "the varying chemical structure and properties of the R-group that make the amino acids different from one another".
Can someone explain what the heck that means in layman's terms, please? Does it even make sense? Can you guys get me some examples? (Simple ones, because I am a thiiiick human. Sometimes I question WHY I DO BIOLOGY AT ALL, honestly.) >:( >:( >:( >:(

((I apologise for my absolute fury, but I've been struggling with this concept for two weeks, and I just cannot seem to grasp it!!  :'())
lol

basically every amino acid would be the same as they all contain a carboxyl group and a amine group. The thing that changes is the R group which is why its also called the variable group(variable meaning change). Type up "amino acids" on google and take a look at the images with the highlighted R groups, note that gylcine has just a H atom whereas something like serine has a -CH2-OH. If you take a look, H2N,COOH are present within both molecules and the only disparity is the functional R group which distinguishes one amino acid from another.
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Poet

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Re: VCE Biology Question Thread
« Reply #9902 on: February 18, 2018, 03:39:10 pm »
0
lol

basically every amino acid would be the same as they all contain a carboxyl group and a amine group. The thing that changes is the R group which is why its also called the variable group(variable meaning change). Type up "amino acids" on google and take a look at the images with the highlighted R groups, note that gylcine has just a H atom whereas something like serine has a -CH2-OH. If you take a look, H2N,COOH are present within both molecules and the only disparity is the functional R group which distinguishes one amino acid from another.

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PopcornTime

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Re: VCE Biology Question Thread
« Reply #9903 on: February 21, 2018, 11:26:47 pm »
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What is the purpose of cycling between NADH and NAD+, ATP and ADP and NADP+ and NADPH?

I am more so confused about how to phrase my answer, but it would have to do with the fact that reusing molecules allows for conservation of energy.

Thanks

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Re: VCE Biology Question Thread
« Reply #9904 on: February 21, 2018, 11:33:42 pm »
+1
What is the purpose of cycling between NADH and NAD+, ATP and ADP and NADP+ and NADPH?

I am more so confused about how to phrase my answer, but it would have to do with the fact that reusing molecules allows for conservation of energy.

Thanks
The hydrogen ions need to be broken off anyway (eg. To power ATP synthase in cellular respiration) and the phosphate needs to be broken off to release energy, so there’s no point throwing away the unloaded molecule you end up with.

I don’t know exactly what sort of answer you are after (it depends on the question) but if you’re being asked why they are recycled I would just say something like:
Unloaded carrier molecules are reused by the cell as it is faster than making new molecules and it conserves resources and energy.
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PopcornTime

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Re: VCE Biology Question Thread
« Reply #9905 on: February 22, 2018, 08:36:56 am »
0
Not sure where to start for this question:

Design/Outline an experiment to test the effect of inhibitors on enzyme activity.


PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9906 on: February 22, 2018, 08:52:15 am »
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Not sure where to start for this question:

Design/Outline an experiment to test the effect of inhibitors on enzyme activity.
Basically it just wants to know your method, but in paragraph form (sometimes you can draw diagrams too).
You need to include
-IV
-DV
-controlled variables
-sample size
-population
-control and experimental groups
Basically just include everything that you would need to know in order to run the experiment.
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Poet

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Re: VCE Biology Question Thread
« Reply #9907 on: February 22, 2018, 05:55:29 pm »
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Hi all! Just one question:
I can't quite seem to grasp the concept of substrates and their role with enzymes? Could someone please explain the role of substrates and enzymes?
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Re: VCE Biology Question Thread
« Reply #9908 on: February 22, 2018, 06:19:21 pm »
+3
Hi all! Just one question:
I can't quite seem to grasp the concept of substrates and their role with enzymes? Could someone please explain the role of substrates and enzymes?
The enzyme catalyses (instigates) a reaction. The substrate is the thing that the reaction happens to (it is just a molecule - any molecule that binds to an enzyme can be called a substrate). Enzymes place a little bit of force on substrates, forcing them to change in one of two ways. They either:
-Cause bonds holding the substrate together to break, resulting in 2 or more products.
-Cause bonds between 2 or more substrates to form, resulting in 1 product.

Without enzymes it would take far, far longer and more energy, for the substrate to change (for a chemical reaction to occur). Imagine 2 substrates just floating around in your cell. Without enzymes it is highly unlikely they will ever fuse together, however an enzyme is able to bond to them, holding them against each other in the correct place to allow bonds to form.

The enzyme stresses (places pressure on) the bonds, which is explained by the induced fit theory - this says that when substrate/s bind the enzyme changes shape slightly.

« Last Edit: February 22, 2018, 06:30:16 pm by PhoenixxFire »
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PopcornTime

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Re: VCE Biology Question Thread
« Reply #9909 on: February 22, 2018, 08:02:12 pm »
0

Basically it just wants to know your method, but in paragraph form (sometimes you can draw diagrams too).
You need to include
-IV
-DV
-controlled variables
-sample size
-population
-control and experimental groups
Basically just include everything that you would need to know in order to run the experiment.

Do we have to do paragraph form or can we do dot point answers for the above?


Poet

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Re: VCE Biology Question Thread
« Reply #9910 on: February 22, 2018, 08:06:22 pm »
+1
Do we have to do paragraph form or can we do dot point answers for the above?

In VCE Biology practical reports, you would always use paragraph form. However, if the question only calls for an outline of what you would do, (as seen in your previous question), you can use dots points by simply replacing the variables, etc., with your own answers. :)
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9911 on: February 22, 2018, 08:13:36 pm »
+2
Do we have to do paragraph form or can we do dot point answers for the above?
You can use dot points for some parts however simply having a dot point saying something like ‘a positive control was used’ would not be enough. You would need to say something like ‘a sample was placed under a white light which acted as a positive control and another sample was placed under no light which acted as a negative control’ which is why using paragraphs can be easier.

If the question says describe you need to use paragraphs.

Edit: Just to clarify, the reason I specified paragraphs is because you don’t want to just copy a method.
A method would look like:
-cut 100 leaf disks
-place 20 is each into 5 beakers
-place one beaker under each of red light, blue light, green light, white light, no light.

Whereas an answer to the question would look like:
100 leaf discs were cut from similar sized leaves using the same straw to ensure they were as close as possible to the same size. 20 leaf discs were placed into each of the 5 previously prepared beakers. A beaker was placed under each of the experimental conditions (red, blue, green light). A beaker was also placed under a white light to act as a positive control and another beaker was placed under no light to act as a negative control.
« Last Edit: February 22, 2018, 08:29:17 pm by PhoenixxFire »
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Sunset.T

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Re: VCE Biology Question Thread
« Reply #9912 on: February 23, 2018, 07:17:20 pm »
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Hello. Okay this is my first year ever doing biology, so i feel a little behind. I appologise for a long thing and all the questions. I'll number the questions.
We have completed 2 practical experiments on enzymes. The first one was testing the rate of reaction between Liver Catalase and hydrogen peroxide in 3 different pH buffers (4, 7 & 10).
The second one was testing the rate of reaction between Liver Catalase and hydrogen peroxide at 4 different temperature; Ice cold, room temp., 40 degrees, and 80degrees. Although, what we did was put the test tubes with Liver in water in a bath of each of those temps for 10 mins and then we had to let them all sit to return to room temperature. 1. So i'm guessing the aim wasn't to see how temperature effects the rate of reaction, but instead how temperature effects the enzyme in a way which in turn effects the reaction rate? Unless that's legit the same thing idk.

For both practicals, the ROR was tested using a stop watch, a ruler, and a splint. It wasn't specified exactly how to use those tools to measure.
I saw some students timing the reaction up until the bubbles started to dissappear. However i was timing how long it took for the bubbles to reach a maximum height. So i stopped timing when the bubbles stopped going higher and were instead building at the same rate as they dissappeared. 2. Not sure if that's a correct way of doing it?

Then,  i assumed that when the bubbles had stopped increasing in height that perhaps that meant the Enzyme was saturated. 3. But if each trial had the same amount of liver and the same amount of Hydrogen Peroxide then shouldnt all the trials have reached the same maximum height but just at different speeds? 4. Most trials had a height difference of between 0.2 and 1cm. Why didn't all the trials climb to the same height? Or is that due to varying degrees of enzyme denaturation?
5&6. Actually, if the bubbles stopped growing in height, could that mean that there is simply less hydrogen peroxide molecues floating around and so less collisions occuring instead of the enzyme being saturated? bc the substrate wasnt increased so i guess the enzyme wouldn't have become saturated?

So i know catalase optimal pH and temperature is 7 and 37 ish degrees right? But i think the reaction was quickest in the room temperature trial compared to the 40 degree one. Thing is, there are discussion questions on this, one of which asks to write the optimal pH and temperature. the pH everyone knows is 7, 7. but how could we know the temperature when the only trial that was close to that temp was the 40 degree one? I originally assumed the optimal would be around 37 degrees bc i know that's basically body temperature and Catalase in inside the body. 8. I'm just confused, does that mean the question is expecting us to apply some logic and know that the body temp is around 37?

I understand that the 80degree trial definitely caused the enzymes to be permanantly  denatured, as there was only 0.01cm of bubbles produced and there was no oxygen when we used the splint. 9. But what exactly would the ice water have done to the enzyme? I at first thought that cold temperatures just slow everything down. But after bathing the liver in ice water, we left it to go to room temperature, so wouldn't that speed things back up a little? 10. Or does the cold temperatures have a long lasting effect on the enzyme even after warming up to room temperature (which may have been higher than 20 degrees because it was a fairly warm day)? i should add, there was a reaction with the ice trial, it was slower than the room temp and 40 degree trial but it still seemed to be just as reactive as those two, but it slowed down quicker and reached a lower bubble height.
11. Basically, how does the cold temp effect the actual enzyme structure? or does it just slow it down. this one really confused me.

Half of this probs makes no sense. Sorry for the detail, i've never been good at being concise.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9913 on: February 23, 2018, 07:40:38 pm »
+6
1) You're correct, because you changed them back to room temperature you were measuring how permanent the effect of temperature change was.

2) Yep, I would have done it your way. The reaction has stopped once the bubbles stop being produced.

3) It did not mean the enzyme was saturated - if it was saturated you would see a constant speed of reaction, the reaction would be occurring at its fastest rate possible so the bubbles would still be appearing, it would just not get faster.

4) It depends which tests were lower. If it was in the more extreme conditions then yes it could be due to some of the enzymes being denatured - or you could have just put slightly different amounts of hydrogen peroxide into your beakers.

5/6) Yep it would have meant that the reaction rate had either slowed to the point where you could no longer see an increase, or it had stopped. A decrease in hydrogen peroxide floating around would result in the rate of reaction decreasing so it is likely that at this point there was very little or no hydrogen peroxide left.

7/8) It depends on the question. If they want you to base the answer solely off your results they will normally say so (eg. 'state the optimal temperature with reference to your results'). The 40 degree one was cooled to room temperature, so when the reaction occurred they were no different. It is possible that some of the enzymes were denatured from the heating which would have slowed the reaction down.

9/10) Cooling enzymes down has no permanent effect once they have been heated up again, so the difference in results would mean that either it wasn't properly warmed back up or you made an error when making that beaker.

11) Cold temperatures mean less kinetic energy - everything moves slower. Molecules moving slower means they are less likely to bump into each other, and therefore that it is less likely for reactions to occur. It does nothing to the actual enzymes structure which is why it is not permanent. Only high temperatures have permanent effects (and extreme pH's in either direction).
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Re: VCE Biology Question Thread
« Reply #9914 on: February 28, 2018, 06:58:46 am »
0
Hi.
Just wondering, during condensation polymerisation of nucleotides to make DNA, does it output H2O or 2 phosphates?
My teacher said H2O, however edrolo said 2 phosphates, so not really sure now.
Thanks! ;)