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TEAS Test Questions on the Action of Enzymes

In looking through sample TEAS test questions to address for my pre-nursing students I came across these two, both on the topic of enzyme action:

Image

An enzyme processing a substrate A + B –> AB

 

1. Which of the following statements about enzymes is not true?

A. Enzymes are catalysts. 
B. Almost all enzymes are proteins. 
C. Enzymes operate most efficiently at optimum pH. 
D. Enzymes are destroyed during chemical reactions.

2. Which of the following is considered a model for enzyme action?

A. Lock and Key model 
B. Enzyme interaction model 
C. Transformation model 
D. Transcription model

Enzyme action is key to cell survival, indeed, it is the basis of all that a cell does.  Conventiently, Question #1 help define exactly what an enzyme is.

Which of the following statements about enzymes is not true?

Before answering the question, I have to stop and remind test-takers to read carefully. If I were to get this question, the first thing I would do is underline, box, or otherwise note the word ‘NOT’ so that it is clearly obvious and I will not later come back and ‘read through’ this word. Even if I can answer the question easily, I would still mark this. So, restated:

Which of the following statements about enzymes is NOT true?

Instead of a multiple-choice question, this should be approached as a series of T/F questions. I wouldn’t actually re-write these (the object is not to make more work for you, but, to make your questions clear)

  1. A.     Enzymes are catalysts. 


True –  An enzyme is a catalyst. The clearest definition of what an enzyme is, is… ‘Enzymes act as biological catalysts.’ To further emphasize this, let’s define a catalyst by skipping down to ‘D’.

D. Enzymes are destroyed during chemical reactions

False – A catalyst is defined as a substance that takes part in a reaction, but is not consumed (altered / changed) by the reaction. Therefore, if enzymes are catalysts, then this must be false. You could stop here, but just to be sure, I always read through the other answers to make sure that there is no other answer that also appears true.

B.     Almost all enzymes are proteins.

  1. Image

Well…. I have a difficult time with this one. ‘Almost’ is not the kind of word you want to see in a question like this. Many enzymes are proteins, but many are also ribozymes, meaning enzymes composed of RNA. The ribosome is an excellent example of a ribozyme, consisting of mostly rRNA and a small protein component as well.

Luckily, we have already seen that ‘D’ is clearly false, while this is merely a questionable answer.


C. Enzymes operate most efficiently at optimum pH. 


Image

Each enzyme may have its own optimal conditions

True – Enzymes, like all molecules, will have an optimal pH. This is because pH changes will result in changes in how a molecule folds. As I have mentioned many times before, ‘Form Dictates Function’ – if a molecule folds correctly, it will function correctly.; if it folds incorrectly, then it will (almost always) function incorrectly, or not at all.

Which of the following statements about enzymes is NOT true?

D. Enzymes are destroyed during chemical reactions

Next question…

2. Which of the following is considered a model for enzyme action?

A. Lock and Key model 
B. Enzyme interaction model 
C. Transformation model 
D. Transcription model

A.           Lock and Key model 
Image

The lock and key model describes how an enzyme and its substrate fit together precisely as a key fits a lock. This analogy describes both the precision of the fit as well as the specificity a key has for its lock.

 B.              Enzyme interaction model 


These are just words. They sound right, but that’s as far as it goes.

C.           Transformation model

Again, these are just words. In this case, not even the right words. ‘Transformation’ refers to either the transfer of DNA into a cell (as with plasmid DNA into a bacteria) or the mutation of DNA in a cell such that it ‘transforms’ into a cancer cell.


D. Transcription model

            ‘Transcription’ refers to the copying of genetic information from DNA to RNA as in the central dogma.

 

 
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Posted by on January 1, 2014 in Uncategorized

 

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function: AcceptGuess

The next function I had to work out was how to accept the player’s guess in a way that would set up an array in a way that each digit of the player’s guess is an entry in the array. This would give me an array containing the secretCode generated by the computer and an array containing the guess generated by the user. All I’d have to do then, in cycle through the arrays to make comparisons (If only it was so easy).

So, this function proved to be quite simple:

 

 

//accepts guess from user and parses it into an array of ‘code’ length

acceptGuess = function(code,numbers){

    console.log(“***acceptGuess function reached***”);

    var guess = prompt(“Make a guess at the secret code (“+code+”digits/1-“+numbers+”)”);

    //need to add something to ensure guess is within parameters

        console.log(“guesslength is “+guess.length);

        console.log(“code is “+code);

        var codeNum = code * 1;

        console.log(typeof guess.length);

        console.log(typeof codeNum);

        if (guess.length === codeNum){

        console.log(“got inside the loop”);

            for (i=0;i>code; i++){

                console.log(“guess[i] = “+guess[i]);

                guessDigit[i] =guess.substring(i,i+1);

                console.log(guessDigit[i]);

            }

            return guessDigit;

        } else {

             console.log(“invalid guess”);

        }

};

The only problem I had with this was that the parameter ‘code’ comes through as a string. Note the two lines of code:

console.log(typeof guess.length);

console.log(typeof codeNum);

I’ve realized that the best way to debug is to have console.log lines everywhere that write out what is going on step by step. ‘typeof’ has been a very valuable code that I use whenever it looks like math isn’t working – so far it has uncovered the problem nearly 100% of the time.

Javascript will convert it to a ‘number’ if you do any mathematical function with the variable. An easy way to do this without messing anything up is to multiply by 1. To be even more careful, I created a new variable, ‘codeNum’, to hold this value as a number. The following line did that:

var codeNum = code * 1;

 

Last piece in my next post: comparing the values of the guess with the secret code. I just finished this 5 minutes ago after running myself ragged for several days (it was the reason I was dilly dallying about this posting)

 

 
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Posted by on July 3, 2012 in Uncategorized

 

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function: Generating a Secret Code

I knew this would be a more challenging function for me. From the outset I’ve been considering a couple different strategies for accomplishing this function. One idea was to have the secret code be an object – one thing I liked about this was that I’ve never used an Object in any coding before aside from the codecademy exercises where you have a lot of help in getting it right. The other idea was to make the guess an Array. I should say that I’ve never used an array before for anything that wasn’t a reformatted exercise either. I also thought that perhaps an array might be a bit easier too.

S0, I chose to go forward with the array idea. It makes sense to me. An array is a list of variables all collected together and in a fixed order (the first position is called [0], the second is [1] and so on. Some examples of arrays are:

var x = [1,2,3,5,8,13];

console.log(x[0]); would print the number in the ‘0’ position to the console, (i.e. 1)

console.log(x[3]); would print the number in the ‘3’ position to the console, (i.e. 5)

Array can also be lists of strings:

var cats = [“William”, “Oliver”, “Chloe”, “Anna”];

console.log(cats[1]); would print the number in the ‘1’ position to the console, (i.e. Oliver)

 

What I like about this is that the numbers have order – just what I’ll need to set and crack a combination.

Here’s the function I came up with to do this – It wasn’t easy for me, at one point I managed to make an array that had another nested array inside of it. I couldn’t make heads or tails of it, but thanks to some good people on stack overflow, the problem was identified and solved.

 

 

//sets up an array of numbers that will be the secret code

// code is the number of digits, number is the integers used for each digit

setSecretCode = function(code,numbers){

var secretCode = “0”;

var secret = [];

console.log(“***reached setSecretCode function***”);

for (i=0; i < code; i++){

secret[i] = Math.floor(Math.random()*numbers+1);

}

return secret; to return result to be used going forward

};

 

This function is called:

var secret = setSecretCode(enteredCode,enteredNumber);

 

//printout of array for debugging

console.log(“secret code is: “+ secret);

 

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