Biological Molecules Flashcards
Summary
Name 9 properties of water
High specific heat capacity High latent heat of evaporation Ice is less dense that water Good solvent Adhesion Cohesion Surface tension Transparent High density as a liquid
How is the cohesion property of helpful for a plant?
Cohesion is the attraction of similar molecules
This helps pull water molecules up xylem vessels
How is the adhesion property of water helpful for a plant?
Adhesion is the hydrogen bonding of unlike molecules
Helps water to adhere to xylem vessel walls
What bonds join monosaccharides?
Glycosidic bonds
What monosaccharides make…
Maltose
Sucrose
Lactose
Maltose = 2x Glucose
Sucrose = Glucose + Fructose
Lactose = Glucose + Galactose
What’s a feature of starch making it a good storage molecule?
It’s insoluble so plant cell won’t swell
What are the features of Amylose?
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Unbranched chain of a-glucose
Compacts easily so good for storage
Only 1,4 glycosidic bonds
What are the features of Amylopectin?
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Branched chain with 1,4 + 1,6 glycosidic bonds
Branches allow enzymes to break down glycosidic bonds easily
Glucose released quickly
What is the bonding in lipids/fats?
Ester bonds
Tryglyceride features when used to store energy
▪▪
Lipids contain twice as much energy per gram than carbohydrates (long hydrocarbon chain has lots of energy
Insoluble so water won’t enter via osmosis so cell won’t swell / won’t dissolve in water
Role of cholesterol
Makes membrane less fluid and more rigid
Binds to hydrophobic tails of phospholipid and causes it to pack together more closely
What’s the bond between proteins?
Peptide bonds
Define primary structure
The sequence and order of amino acids in the chain
What are the 2 secondary structures?
▪▪
What are the bond present?
A- helix + B-pleated sheets
Hydrogen bonds
Define tertiary structure
What binds are present?
3D shape of the protein from further twisting and coiling
Hydrogen bonding
Ionic bonding
Disulfide bridges
Define quaternary structure
Multiple polypeptide chains held together by peptide bonds
Name a globular protein
What are 4 features of it
Haemoglobin
Quarternary structure
Hydrophilic regions on outside, water soluble
4 polypeptide subunits
Each subunit has one haem- group with Fe 2+ ion – this is a prosthetic group
Name a fibrous protein
4 features of it
Collagen
3 polypeptide chains
Quaternary structure
Insoluble
No prosthetic group
Similarities of collagen and haemoglobin?
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Peptide bonds
Amino acid chain
Helix
Quaternary level Protein
Hydrogen, ionic bonds and disulphide bridges
Subunits
Test for proteins?
Positive result observation
Biuret test
Solution turns purple (from blue)
Test for starch
Positive result observation
Iodine test
Solution turns blue-black (from brown-orange)
Test for lipids
Positive result observation
Emulsion test
Solution turns milky (from colourless)
Test for reducing sugar
How it’s done
Positive result observation
Benedict’s test
Add Benedict’s solution and heat
Green, yellow, orange, brick red (from blue)
Test for non reducing sugars
How is it done?
Positive result observation
Benedict’s test
Add dilute HCl and heat
Add sodium hydrogen carbonate
Heat sample with Benedict’s reagent
Solution green, yellow, orange, brick red (from blue)
