Mephistopheles07
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This is our interview preparation group for sharing potential questions and how we might go about approaching them.
Remember, we aren’t allowed to share the actual interview questions but rather only questions that could potentially come up.
I will be starting with some of the ones I have found online:
- What causes the common cold and why is there no cure? How does the flu vaccine work?

- Why do we need ATP, why not just release energy from glucose directly?

- How much of human behaviour is genetically determined?

- What techniques could be used to date how long a disease has existed in a population?

- Why are there only 20 amino acids?
Last edited by Mephistopheles07; 11 months ago
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Medwizard
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Question 3 looks good. I think my main answer would revolve around epigenetics since that can switch certain genes on and off.
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Medwizard
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What techniques could be used to date how long a disease has existed in a population?

This is more to do with finding how the levels of antibodies specific to the pathogen has changed. I think it would work if you test blood samples of all the population on yearly basis. But then those technologies for doing this did not exist back then....

Maybe applying the principle of radioactive dating may help? We find if there's a certain isotope of an element in the pathogen that is radioactive then analyse dead bodies/fossils for level of radioactivity.

Perhaps looking at DNA to see how long adaptations against the disease have existed and that could help us to answer the question.
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MedicPls
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hey guys, what colleges do you have a med interview at? Mine's at fitz
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molecule141
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Pembroke
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lelak1
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Mine's at Emmanuel

I have 2 and I think most people do but is there much difference between them in terms of what they ask?
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Student+
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What causes the common cold and why is there no cure?
Talk about antibodies and antigens and how the virus that causes the common cold mutates so the shape of ‘it’s antigens become a different cells so memory cells produced are useless etc.

Why are there only 20 amino acids?
Degenerate code

Why ATP and not glucose?
Not sure about this question.
I guess maybe glucose isn’t efficient enough.its soluble so removing or adding it can affect the water potential of the blood.
Or maybe ATP can be produced from proteins and lipids too whereas you need carbohydrates for glucose.
Idk anyone have any ideas?
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Dr. Doc Thor
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(Original post by Student+)
What causes the common cold and why is there no cure?
Talk about antibodies and antigens and how the virus that causes the common cold mutates so the shape of ‘it’s antigens become a different cells so memory cells produced are useless etc.

Why are there only 20 amino acids?
Degenerate code

Why ATP and not glucose?
Not sure about this question.
I guess maybe glucose isn’t efficient enough.its soluble so removing or adding it can affect the water potential of the blood.
Or maybe ATP can be produced from proteins and lipids too whereas you need carbohydrates for glucose.
Idk anyone have any ideas?
I think it may also be relating to ATP releasing small packets of energy that can more easily be transported and distributed across cells. Whilst breakdown of glucose releases a larger amount of energy that would all have to be used in one go and so could not be distributed so easily.
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Student+
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(Original post by Dr. Doc Thor)
I think it may also be relating to ATP releasing small packets of energy that can more easily be transported and distributed across cells. Whilst breakdown of glucose releases a larger amount of energy that would all have to be used in one go and so could not be distributed so easily.
Ahh good point
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Mephistopheles07
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(Original post by eshakaur11)
Mine's at Emmanuel

I have 2 and I think most people do but is there much difference between them in terms of what they ask?
Sometimes. It has more to do with competition than anything. For the most competitive ones like Trinity, they do not really waste time on personal statement questions and unless you give exceptionally good answers on the academic questions, you unfortunately have a higher chance of being rejected.
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HeIIIo
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Gonville and Caius
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Ricco.af
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(Original post by Mephistopheles07)
This is our interview preparation group for sharing potential questions and how we might go about approaching them.
Remember, we aren’t allowed to share the actual interview questions but rather only questions that could potentially come up.
I will be starting with some of the ones I have found online:
- What causes the common cold and why is there no cure? How does the flu vaccine work?

- Why do we need ATP, why not just release energy from glucose directly?

- How much of human behaviour is genetically determined?

- What techniques could be used to date how long a disease has existed in a population?

- Why are there only 20 amino acids?
Interviewee for St. Catz

for question 5: I think I'd begin by talking about what is meant by the 20 amino acids - specifically that it's talking about the 20 naturally occurring alpha-amino acids, then I'd go on to talk about amino acids usage in nature - proteins etc. and how transcription and translation works off of the basis of the 4 base nucleotides in a species' genome (ATCG) and how each amino acid is coded for by triplet base pairs (codons) and therefore only a maximum of 64 different amino acids would be possible to make via translation. Then I'd talk about how specific the products of amino acid polypeptide chains are through the primary, secondary, tertiary, quarternary structure in that even with the 20 we use there are still so many possible combinations of proteins enzymes etc. that are producible - putting emphasis on the different interactions undergone by different r-groups of amino acids in the polypeptide chains, and how these interactions shape the polypeptide to its function.

Then I'd go to talk about why 20 is beneficial in terms of less is more in the sense of evolution leading to these 20 being optimal in terms of equally spacing properties (the bonding interactions I'd stated before) allowing for maximal variation in structure where necessary, and how it allows for a degenerative coding system to prevent harmful changes due to mutation of the original genome.

I don't know how I'd go about explaining why not less than 20, but I'd probably still talk about something along the lines of maximisation of possible shapes caused by size and interactions of r-groups (disulphide bridges, hydrogen bonding, ionic bonding, etc. within the tertiary structure) making it an efficient set number of different amino acids to yield the highest amount of different structures necessary.

I don't know if this is even legible because I just started waffling, but if I received a question like that I'd assume the interviewer would direct alot.
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shcollin
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The limit of 20 amino acids in most organisms might also be to do with how they attach to tRNA molecules. Maybe the section of tRNA which amino acids bind to can only be specific to 20 amino acids, having more might lead to mistakes in which amino acids attach to which tRNA molecules. Proteins would then be more likely to be abnormal.
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shcollin
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(Original post by Mephistopheles07)
This is our interview preparation group for sharing potential questions and how we might go about approaching them.
Remember, we aren’t allowed to share the actual interview questions but rather only questions that could potentially come up.
I will be starting with some of the ones I have found online:
- What causes the common cold and why is there no cure? How does the flu vaccine work?

- Why do we need ATP, why not just release energy from glucose directly?

- How much of human behaviour is genetically determined?

- What techniques could be used to date how long a disease has existed in a population?

- Why are there only 20 amino acids?
4) -Could look at remnants of pathogens in preserved corpses. Could be antigens specific to certain pathogens which have not been degraded. Then use carbon dating to find out the age of the body.
-Could examine historical sources to see if symptoms of the disease have been described hundreds of years ago.
-Could look at structure of pathogen. If it contains antigens or other features which are known to have come from a common ancestor, you could infer that the pathogen existed for however long.
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Student+
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Here are some Chem questions too:

Why are explosions a risk in flour mills? What stops bags of flour exploding in the kitchen?

How does a glow-stick work?

Why don’t fish freeze?

What issues might there be if you wanted to create a metallic oxide that has good conductive properties but is also transparent?

What is the concentration of water?

Why does iron rust and how can rusting be stopped?

How does blood maintain its pH?

Discuss the bonding in benzene.

How many moles of H2O are there in that cup of water?

Calculate what volume of wine can be drunk to reach the legal concentration of alcohol in the blood for driving?

How would you differentiate between salt and sugar without tasting them?

How do amino acids bond to form a peptide?
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Mephistopheles07
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How would you go about approaching these questions (without looking up the answers)?


- Can you describe an experiment to differentiate between a normal and a multi-resistant strain of bacteria?
- How many genes are there in the genome of a rice plant?
- What does the letter b stand for in b-lymphocyte?
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medapplicant101
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(Original post by Mephistopheles07)
How would you go about approaching these questions (without looking up the answers)?


- Can you describe an experiment to differentiate between a normal and a multi-resistant strain of bacteria?
- How many genes are there in the genome of a rice plant?
- What does the letter b stand for in b-lymphocyte?
In terms of the second question, I think it is to do with where the lymphocytes are matured. Both t and b are made in bone marrow but the t lymphocytes are matured in the Thymus and the B in the Bone marrow. Just something we learn in AS bio?
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Ricco.af
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(Original post by Ricco.af)
Interviewee for St. Catz

for question 5: I think I'd begin by talking about what is meant by the 20 amino acids - specifically that it's talking about the 20 naturally occurring alpha-amino acids, then I'd go on to talk about amino acids usage in nature - proteins etc. and how transcription and translation works off of the basis of the 4 base nucleotides in a species' genome (ATCG) and how each amino acid is coded for by triplet base pairs (codons) and therefore only a maximum of 64 different amino acids would be possible to make via translation. Then I'd talk about how specific the products of amino acid polypeptide chains are through the primary, secondary, tertiary, quarternary structure in that even with the 20 we use there are still so many possible combinations of proteins enzymes etc. that are producible - putting emphasis on the different interactions undergone by different r-groups of amino acids in the polypeptide chains, and how these interactions shape the polypeptide to its function.

Then I'd go to talk about why 20 is beneficial in terms of less is more in the sense of evolution leading to these 20 being optimal in terms of equally spacing properties (the bonding interactions I'd stated before) allowing for maximal variation in structure where necessary, and how it allows for a degenerative coding system to prevent harmful changes due to mutation of the original genome.

I don't know how I'd go about explaining why not less than 20, but I'd probably still talk about something along the lines of maximisation of possible shapes caused by size and interactions of r-groups (disulphide bridges, hydrogen bonding, ionic bonding, etc. within the tertiary structure) making it an efficient set number of different amino acids to yield the highest amount of different structures necessary.

I don't know if this is even legible because I just started waffling, but if I received a question like that I'd assume the interviewer would direct alot.
(Original post by shcollin)
The limit of 20 amino acids in most organisms might also be to do with how they attach to tRNA molecules. Maybe the section of tRNA which amino acids bind to can only be specific to 20 amino acids, having more might lead to mistakes in which amino acids attach to which tRNA molecules. Proteins would then be more likely to be abnormal.
Yeah came to say that conclusion just now as I realised that could also be a factor while revising, also I’d assume there wouldn’t be as much variation in alpha amino acids used universally due to how nutrients are cycled in nature and so would remain constant to the most recurring and most diverse amino acid found in early evolution.
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RM_Asclepius
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ATP hydrolysis is a one-step process and therefore allows for the rapid release of energy whereas energy from glucose is released in a multi-step process (glycolysis). ATP hydrolysis also releases energy in small, manageable quantities.

For the amino acids question, maybe because the R group has to bond to carbon, certain groups would make the R group too reactive (if fluorine was the R group it would make the amino acid highly polar), certain R groups might be impossible (e.g. any noble gases, group 1 or 2 elements). This might limit the number of naturally occurring amino acids to 20?
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R T
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You can hydrolyse glucose in one step with the correct protein and release a lot of energy. You could actually be far more efficient doing this than breaking down the steps into chunks.

It's true that ATP >< ADP is an easily reversible reaction with a discrete, small amount of energy that should be manageable, but why ATP is used is almost an impossible question to answer; it's like asking why the exact structure of DNA is exactly so; and not subtly different. We can examine the structure of these molecules and rationalise why their structure is good and helps their functionality, but knowing exactly why life evolved to use these molecules and not others is a question you could spend your whole life thinking about. Attaining that level of knowledge and understanding of biochemistry would mean being knowledgable enough to design molecules that on a molecular level can be better than proteins, DNA and RNA for performing tasks. Humans are at the very least centuries away from such a feat.

An important point to mention in ATP is that the glucose-ATP cycle is very important outside of glucose and ATP also. A lot of the intermediary products are used in various other biochemical cycles and can be useful to the body in different ways. Contrast this with a design where you just take glucose and immediately smash it into energy (which is really only good for one thing - energy production). The system has evolved around this state and helps carefully monitor a number of things in the cell.

It's hard to appreciate at A-Level where you are just taught cycles independently of one another, but really biochemistry in cells is a massive mish-mash of various cycles that all feed into each other and depend on each other to function properly.



Re; 20 amino acids.
This is a really great question because it's easy to get a handle on why degeneracy is important in the context of how frequently DNA gets damaged or mis-replicates. By looking at the patterns, a smart A-Level student could probably guess what the most common mutations or mis-replication events are in the cell. I could easily see an Oxbridge interview question stemming from this idea.

Chemically speaking, 20 amino acids might be a bit of a misnomer anyway. It is debatable whether or not 20 is the true number, when most animals cannot even produce tryptophan on their own. Likewise, it is very common to chemically alter amino acid groups in the final protein design.

If we take a reductionist view and think "if a chemical group exists on R, and this chemical group cannot be massive and needs to serve a reasonably different function from the other R groups (amino acids), how many simple examples of this are there for a hydrocarbon based (but with some source of N, P, S) lifeforms?" The 20 amino acids actually cover a very good range of this multidimensional issue (hydrophobic vs hydrophilic, large vs small, flexibility, length, oxidising or reducing power).

Of course, more examples are possible, but we need to remember that cells exist in an aqueous environment and there is a certain limitation to how "dangerous" you can let your basic building blocks be to avoid poisoning yourself. It took a very, very, very long time for life to even start using Oxygen, because of how destructively powerful Oxygen chemistry can be (it is obviously a powerful oxidising agent but also mismanagement of its structure can cause free radicals).
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