Hielly's biology questions!!

[polky]

1) A carbon can form 4 covalent bonds.
2) Cysteine has Sulphur (S) atoms in it's molecular formula, so it can form disulfide bonds with other cysteines or other amino acids that have S as well.

[shinny]

Don't worry about universal solvent...you won't need it. It's just a fairly unused term to describe water.

Functional groups;

A specific group of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.

2. Just going further from polky's, these di-sulfide bonds are the only covalent bonds (these are very strong) which occur ACROSS the polypeptide. These rigid bonds hence often determine the shape of the tertiary and quaternary structures of molecules.

[lacoste]

These rigid bonds hence often determine the shape of the tertiary and quaternary structures of molecules.

For example: molecules such as protein

[shinny]

These rigid bonds hence often determine the shape of the tertiary and quaternary structures of molecules.

For example: molecules such as protein

Well yeh that was kinda implied...cysteine is an amino acid so it'd have to be a protein.

[lacoste]

These rigid bonds hence often determine the shape of the tertiary and quaternary structures of molecules.

For example: molecules such as protein

Well yeh that was kinda implied...cysteine is an amino acid so it'd have to be a protein.

Not necessarily, a protein has to have a specific number of amino acids to be considered a protein. A very short chain of amino acids are called peptides. ie. 20 amino acids of cysteine is a peptide

[shinny]

Well yeh, proteins and peptides. Your use of 'such as' just made it sound like to me that you'd see di-sulfide bridges in something other than these two and that's what I was clarifying.

[lacoste]

Your use of 'such as' just made it sound like to me that you'd see di-sulfide bridges in something other than these two and that's what I was clarifying.

How could I see it other than these two? But if the clarification makes sense to heilly, then good work!

I said 'such as' because most don't remember about peptides but only proteins. And you said that "cysteine is an amino acid so it'd have to be a protein." That often confuses students, but I doubt there will be a question like that in VCAA exam.

It would be better said if you said: Molecules that have quaternary structures, hence, so it'd have to be a protein. 

[lacoste]

And molecules that have quaternary structures have amino acids (e.g cysteine).

[Hielly]

yeah thanks guys, both your explanations have helped me !
appreciate it heaps

[Hielly]

okay not familiar with these terms,
Topic: CARBOHYDRATES
glycosidic links
starch granules

1)explain how the isomeric structure of a carbohydrate may affect its chemical behaviour

thks

[Hielly]

also these questions
TOPIC- lipids

2)outline the key chemical difference between a phospholipid and a triglyceride. (not sure what it means by chemical)

3)explain how the type of fatty acid present in a neutral fat or phosopholipid is related to that molecule's properties.

4) suggest how the cell membrane structure of an ARctic fish might differ from that of tropical fish species.

[beezy4eva]

2. Put simply: A phospholipid is a lipid that has a phosphate group as a part of its structure. A triglyceride is a lipid which has three fatty acid chains as part of its structure ( if that doesnt make sense i can explain further, just not sure how much about fat structures you've already learnt )

3. There are basically two main types of fatty acid chains: Saturated and unsaturated. A saturated chain has no double carbon bonds and hence it is said to be 'flat'. Unsaturated do have carbon double bonds in them, making their chains 'kinked'. Lipids consisting of saturated fats will have higher melting points and will be more thick as liquids. Lipids consisting of unsaturated fats will have lower melting points and will not be as thick.

4. This could have two answers. You could say that an arctic fish will have more unsaturated fats in its cell membrane to avoid its cell membranes congealing in the cold. Or you could say it would have more saturated fats in it (better insulators than unsaturated) and more cholesterol in it, as cholesterol helps maintain the fluidity of the cell membrane.  I'm pretty sure either answer would be accepted.

[Hielly]

2. Put simply: A phospholipid is a lipid that has a phosphate group as a part of its structure. A triglyceride is a lipid which has three fatty acid chains as part of its structure ( if that doesnt make sense i can explain further, just not sure how much about fat structures you've already learnt )

Okay for this question, you mentioned the three fatty acid chains, but isnt that explaining its structure. It asks for the chemical difference ?

thanks for your help on those questions

[hard]

2. Put simply: A phospholipid is a lipid that has a phosphate group as a part of its structure. A triglyceride is a lipid which has three fatty acid chains as part of its structure ( if that doesnt make sense i can explain further, just not sure how much about fat structures you've already learnt )

Okay for this question, you mentioned the three fatty acid chains, but isnt that explaining its structure. It asks for the chemical difference ?

thanks for your help on those questions

no beezy explained it correctly. Basically a phospholipid has a phosphate class attached to the glycerole backbone along with two fatty acids rather than triglyceride, which has three fatty acids attached. that is the chemical structure.

[Hielly]

okay thanks guys.

topic:amino acids

1)explain how the chmistry of amino acids enable them to act as buffers in biological tissues

topic:proteins

2)giving examples, breifely explain how proteins are involved in the following functional roles
a)contractile elemetns:
(my example is actin, but im not sure what they mean by contractile)

3)explain how denaturation destroys protein function.
i simply wrote it is unable to carry out biological functions, pretty sure there's more to it?


Thanks