biochemistry Flashcards
what is the other name for proteins? and what does this mean?
polypeptides- many amino acids
how many amino acids do we have?
20
how many essential amino acids and what does this mean?
9 essential- need to eat, we cannot make
ow many non-essential amino acids and what does this mean?
11 non-essential- body makes
how are amino acids joined?
by a condensation polymerisation reaction which forms a repeating backbone with alternating R groups.
chirality?
amino acids have a chiral carbon centre which means that the have 4 different environments all around- an amine, R, H, carboxy
what are the exceptions in amino acids?
glycine is not chiral
proline changes from the general structure (but still chiral)n
what is the basic end? acidic end?
- amine
- carboxy
how are amino acids categorised?
by the properties of the R group
non-polar
dispersion forces only
+ charge
has an NH3+, NH2+ or NH+
polar
has an OH, C=O
- charge
lost some H forming O-
what does it mean that amino acids can acid as buffers?
they have amphiprotic capacity- act as an acid or base, this leads to conjugate pairs
what aspects does a zwitterion have?
a positive (protonated) and negative (deprotinated) end
- neutral overall
- protonated end is basic and accepts H+ in acidic solutions
- deprotinated end is acidic and donates H+ in basic solutions
- therefore amphiprotic and acts as a buffer
important note in buffering?
R groups can participate
at pH 7?
always zwitterions because neutral
how are dipeptides formed?
water is expelled, allowing C=ONH (amide link or peptide link) to form
what if dipeptides are being broken down?
add water ands its hydrolysis
number of waters lost?
number of amino acids-1
working out number of possibilities
use factorials
how does hydrolysis work?
water is added, the amide link breaks
primary structure
bead chain of amino acids
- peptide bonds (covalent bonds)
secondary structure
hydrogen bonding occurs causing folding on b-sheet or a-helix
tertiary structure
- 4 different types of bonds (governed by R groups)
- dispersion
- ionic (charges)
- hydrogen
- disulphide (S-S)
order of strength
quaternary structure
- when more than one pp chain join together eg. ribosomes, antibodies, haemoglobin
protein function
structure- keratin transport- Hb toxins defence, immunology- antibodies enzymes- biological catalysts
what are enzymes and what do they do?
speed up reactions by lowering activation energy needed to break reactant bonds. this leads to energy conservation (more energy put into increasing collisions) and therefore ensures another energy pathway to be present
what does it mean that enzymes are specific?
an enzyme only functions on a specific substrate. this is linked to their 3D structure and active site (Complementary bonding)
how does the lock and key model work?
when the substrate (key) internal bonds releax, the activation energy is decreased and therefore bonds break more easily