Biological Molecules Flashcards
In what form do amino acids exist in exclusively?
L form
N —> C
In what form do sugars exist in predominantly?
D form
C —> N
What biological bond consisting of 4 atoms is planar?
Peptide bond
What’s the general formula of monosaccharides?
(CH2O)n
- a carbon which is hydrated
What 2 groups do monosaccharides either contain?
Aldehyde (aldoses)
Or ketone (ketones)
What functional group do all monosaccharides possess in aqueous solution?
Hemiacetal
What’s the name of the position next to the ring oxygen?
The anomeric position
What’s the importance of the anomeric position?
It has two forms that can interconvert between alpha and Beta anomers.
This is often the region where two sugars link and becomes rigid.
What reaction joins sugars together?
Condensation reaction
What are three common disaccharides and their monomer units?
Maltose - glucose + glucose
Lactose - glucose + galactose
Sucrose - glucose + fructose
What is the difference between glucose and galactose?
The OH on carbon 4 is flipped - in galactose it is above the plane of the ring.
What is the difference between glucose and mannose?
The OH on carbon 2 is flipped - in mannose it is above the plane of the ring.
How can you identify a glycosidic bond?
They are chiral carbons which are bonded to a heteroatom next to the ring oxygen.
What sugar makes up cell walls?
Cellulose
What word can be used to describe fatty acids?
Amphiphilic - has both hydrophobic and hydrophilic properties
What the difference between oleic acid and stearic acid?
Oleic acid is more reactive due to the double bond in the hydrocarbon chain - molecular handle
Stearic acid is less reactive
Why are butter/lard solids at room temperature?
They are saturated fats and so contain no C=C double bond
Hence possess better stacking - stronger VDW forces and so have a higher melting point
Why are plant oil often liquid at room temperature?
Planet oils are alkenes and so have poorer stacking - lower melting point due to weaker VDW forces
Also have better molecular handle which is metabolised.
What is an acyl group?
Central carbon bound to a methyl group and R group, with a C=O double bond.
Me — C == O
l
R
Where are ester linkages found in Triacylglycerols?
Between glycerol and the fatty acids
What are the key differences between triacylglycerols and phospholipids?
In phospholipids, glycerol is attached to two fatty acids, rather than 3 in TAGs.
Third site on glycerol is attached to phosphate group - which is then bound to a small polar group.
How does a glycolipid differ to a phospholipid?
It contains a sugar instead of a phosphate group
Where are glycosidic bonds found in nucelotides?
Between the sugar and the base
What is a nucleoside?
It’s a nucleotide but without the phosphate group.
What bases are pyrimidines? (Single ring structure)
Thymine
Cytosine
Uracil
What bases are purines? (Double ring structure)
Adenine
Guanine
Where are phosphoanhydride bonds found?
Between phosphate groups (in molecules like ATP)
Where do phosphates join to sugars?
To the C5’ hydroxyl
Where are phosphodiester bonds found?
Between the sugar of one nucleotide and the phosphate of another.
(Phosphodiester backbone of DNA)
Give two important energy transport molecules - excluding ATP. What is the difference between them?
NADP+
NAD+
They are dinucleotide analogues of each other - with only structural difference being a phosphate group
What 4 atoms make up more then 96% of the mass of a cell?
Carbon, hydrogen, nitrogen and oxygen
