quick question

[hard]

i thought bumpppppppppppppppppppp worked

[shinny]

Sigh. I can't exactly remember enough Biology to fully answer the question with respect to every function lipids perform (it's been two years, gimme a break), but I'd say you've gone a bit off topic there and your answer structure is a bit hectic. You're jumping around too much, and you're forcing the examiners to find the marks in a mess of random facts. Try and keep a clear and concise answer which clearly relates each specific property of lipids (non-polar, saturated/non-saturated, thermal insulation properties) to each function (structural component of cell walls, energy storage, thermal insulation, and possibly as chemical messengers). Note that this kind of question is unlikely to come up in exam because it's a bit too general, and that's why you're probably having problems.

[hard]

ahaha yess someone answered! SHINNY TO THE RESCUE! well amm i got confused with the question, i wasn't sure what to write and not to write, as you said it's too general.

[NE2000]

okay neq question:

Relate the structure of lipid molecules to their function.

Answer:

Lipids are classified based on their solubility. This is dependent on two factors: the shape of the molecule and the nature of their intramolecular bonds.
Essentially, lipids have three major functions; i.e. they are energy storers, they are structural components of membranes and they provide a means for specific biological functions such as communication.
It may be noted that most fats and oils of plants and animals are mostly made up of triglyceride molecules. These are basically three fatty acid attached to a glycerol backbone.
Going back to the first feature of lipids being that they sotre energey; fats in animals are saturated. This means that the carbons atoms have only single straight bonds allowing for them to pack closely and form a solid. This is a common mechanism used by many animals such as polar bears to 'store energy' and heat in harsh conditions, or blubber in whales.

from here i'm stuck. not sure whether i should mention phosphophlipids or glycoplipids or cholostrol or whether it has answered the question. can someone help please?

Structure determines function

Lipids are annoying because there's so many different types. I agree with Shinny that the way your answer was going it wasn't really going to get anywhere and was a bit too messy

Also, if this is a textbook question, I've found that some textbooks ask questions that demand really long answers.

Now just some stuff off the top of my head from last year:
Phospholipids have a glycerol backbone with two fatty acids tail attached on one end and a phosphate group attached on the other end. As a result, one end is polar and the other is non-polar (you don't have to say why, they don't expect you to have too much chem knowledge). This relates to its function in membranes of cells and organelles. In this case, the phospholipid molecules arrange into a bilayer, with the hydrophilic heads positioned on the external part of the membrane and the hydrophobic tails positioned in the interior. This allows it to function as a semi-permeable membrane, as the bilayer separates the interstitial fluid from the intracellular cytosol, but it allows hydrophobic molecules like lipid-based hormones to cross the membrane.

Which ties in nicely to the hydrophobic hormones generally derived from another form of lipids called steroids. Steroids are composed of (4?) carbon-based ring with a series of external functional groups. Their shape allows them to function as hormones and bind to secondary messengers (I'm a bit shaky on this part) which can trigger a cascade of events in the cell. Their hydrophobic nature allows them to pass through cell membranes in order to bind to the intracellular receptors they must bind to.

Triglycerides are a common form of lipid molecule and consist of a glycerol backbone bonded to three fatty acid chains. These triglycerides are also non-polar. They can be saturated or unsatured. Saturated triglycerides have only single-bonds in the fatty acid chain and tend to be solid as they pack closer together while unsaturated triglycerides contain double-bonds and hence can be liquid. Saturated triglycerides are collectively known as fats while unsaturated triglycerides are known as oils....then you can say your bit about fats being good insulators...these form of lipids are also energy-rich in that their bonds can be broken to release energy which can be captured in the form of adenosine triphosphate. By memory, the lipid enters sometime in glycolysis...anyway, I'm a bit shaky on this part as well, that's what a year does to you I guess

Looks like I've forgotten how to structure bio answers too lol anywayz

[shinny]

...good luck writing that in an exam.

[NE2000]

...good luck writing that in an exam.

I assumed it wasn't a trial exam question and was a textbook question lol, I just wanted to give him the right information (altho I do have a problem of writing too much in exams). I especially thought there was a bit of confusion in his answers where it came to fat insulation and storing energy...

In an exam they would most probably ask for you to outline how one structural feature of lipids related to one of its functions. In that case I would go with the phospholipid bilayers in the membrane. The fact is that lipids do have many functions, and aren't all due to being non-polar

[hard]

thanks NE2000 but when you say something like "his allows it to function as a semi-permeable membrane, as the bilayer separates the interstitial fluid from the "
there was nothing like that in the book.

the book just provides quite brief definitions.

does all this info come later or do we learn it now. Should i use a diff text book?

[NE2000]

thanks NE2000 but when you say something like "his allows it to function as a semi-permeable membrane, as the bilayer separates the interstitial fluid from the "
there was nothing like that in the book.

the book just provides quite brief definitions.

does all this info come later or do we learn it now. Should i use a diff text book?

What book? I used NoB and it was very detailed

There's a bit of Unit One there in my explanation as well so I think a quick skim over a unit 1/2 textbook might serve you well before school starts.

interstitial fluid = tissue fluid = the fluid that exists between cells in tissues. It is derived from interstetes which is the gap between the cells, so interstitial fluid just flows on from that

semi-permeable should be in your book and just refers to the fact that it allows some things through (is permeable to those things) while it doesn't let other things through

the membrane divides cells from the external and divides organelles from the cytosol

altho...now that I think about it if you haven't done organelles and stuff yet then yeah you can expect all this information to be there later in the book. In which case I'm sorry for possible unnecessarily confusing