Biological molecules and Nucleic acids

A study guide that covers Biological molecules( except carbohydrates) and nucleic acids

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  • Created on: 04-12-11 19:17
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Study Guide- Half term 2 - Biological molecules and Nucleic acids
A polysaccharide chain attached to a protein on the cell membrane( phospholipid
bilayer). They act as receptors in cell signaling.
Cell signaling- Communication between cells.
Glycoprotein works as a receptor by;
allowing cells to work together through he action of hormones to trigger a response
within the cell.
Triglyceride Phospholipid
3 fatty acid chains 2 fatty acid chains
no phosphate contains a
group phosphate group
no extra alcohol contains an extra
attached alcohol attached
to the phosphate
all 3 carbons are the 3rd carbon in
the same way the glycerol is
round rotated 180
Bond together through condensation reaction
Form ester bonds.
Break down through hydrolysis.
Are energy store molecules.
They are insoluble- don't let water enter the cell by osmosis
They bundle together in insoluble droplets as the fatty acid tails(hydrophobic) face
The long hydrocarbon fatty acid tails contain a lot of energy when broken down.
The phosphate group is hydrophilic
The fatty acid tails are hydrophobic.
They form a bilayer as the tails face inwards and heads face out with water on either
The inside of the bilayer is hydrophobic so water soluble substances cannot pass
through it easily.
Biochemical tests for molecules
Biuret test- for proteins
-solution needs to be alkali so add a few drops of sodium hydroxide.
Add copper (II) sulphate to solution
If purple layer forms then protein is present
If solution remains completely blue then there is no protein.
Iodine test- for starch
Add iodine dissolved in a solution of potassium iodide solution to the sample.
If it goes blue-black starch is present
If it remains brown -orange then no starch

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Study Guide- Half term 2 - Biological molecules and Nucleic acids
Emulsion test- for lipids
add ethanol and shake for approximately 1 minute.
if it goes cloudy/milk lipids present
No lipids and it stays clear.…read more

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Study Guide- Half term 2 - Biological molecules and Nucleic acids
Hydrophilic and hydrophobic interaction- hydrophobic amino acids go in the center
and hydrophilic amino acids go to the outside.
R groups can determine the tertiary structure of protein because the r group could
be either hydrophobic or hydrophilic, have a positive or a negative charge( could
cause ionic bonding), disulphide bridges between cysteine.
Quaternary structure-
an protein made up of more than one amino acid chain( polypeptide).…read more

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Study Guide- Half term 2 - Biological molecules and Nucleic acids
Gene code
A gene code is for the coding of a sequence of amino acids
The product of nucleotides
If a sequence of nucleotides were to be change the the final product would change
forming a different sequence of amino acids( primary structure)
This would then create a different tertiary structure.
The product would have different function.…read more


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