Biochem Flashcards
What are the bond strengths strongest to weakest
covalent–>ionic–>hydrogen–>hydrophobic interactions–>vanderwaals
Redox reations
OILRIG- one molecule is reduced and one is oxidised
what is electronegativity
the attractive force that an atomic nucleus exerts on electrons
talk about the electronegativity of carbon and hydrogen
carbon>hydrogen.. carbon has a greater attractive force for electrons, so it gains electrons, therefore it is reduced and hydrogen is oxidised
Carbohyrates
monosaccharides- glucose
disaccharides- lactose
polysaccharides-cellulose, glycogen (alpha 1-4 occationally alpha 1-6)
1st law of thermodynamics
energy neither created nor destroyed
2nd law of thermodynamics
energy converted from one form to another, some of that energy become unavailable to do the work (ie energ is lost and never 100% effective)
Change in free energy (Kj/mol) DeltaG
DeltaG = (energy of products {delta H}) - (energy of reactants {T delta S} )
if free energy is negative
exergonic (can occur spontaneously) ie products have less fre energy than reactants
if free energy is positive
endergonic (cannot occur spontaneously - requires energy e.g. walking upstairs) ie products have more free energy than the reactants
at equlibrium delta G=0 what does this mean
readily reversible reactions
Ka=
acid dissociation constant
pH=
measurement of how many H+ ions in a solution
Reaction spontaneity can be achieved by
- change in conc of a reactant
- coupling with highly favourable processes
- both of the above help delta G become neg
protein structures
Primary - sequence of amino acids
Secondary - formation of backbone (polypeptide)
Tertiary - 3d structure
Quaternary - Spatial arrangement of multiple subunits (disulphide bonds hold proteins together)
The N terminal of a peptide chain is +ve due to NH3
…
The C terminal of a peptide chain is -ve
..
what is a prokaryote
microscopic single cell organism that does not have a defined nucleus
what is a eukaryote
normal cell with nucleus
nucleoside
base+sugar
nucleotide
nucleoside+ phosphate
Purines
adenine and guanine
Pyrimidines
uracil, thymine and cytosine
what are phosphodiester bonds
bonds between 3’ OH groups and 5’ triphosphate
base pairing
a-t
c-g
DNA polymerase
can only add to existing nucleic acids, cannot start sythesis on its own, requires RNA primer to start replicatoin
rRNA (ribosomal)
combines with proteins to form ribosomes where protein synthesis takes place
tRNA (transfer)
carries amino acids to be incorporated into proteins, anticodons consist of 3 nucleotides
mRNA (messanger)
stable RNA, carries genetic information for protein synthesis
poll II
synthesises all mRNA
transcription
RNA polymerase binding
oDetects initiation sites on DNA (promoters)
oRequires transcription factors
DNA chain separation
oUnwinding of DNA
Transcription initiation
oSelection of first nucleotide of growing RNA
oRequired additional general transcription factors
Elongation
oAddition of further nucleotides to RNA chain
oRNA synthesised in 5’ - 3’ direction
Termination
oRelease of finished RNA
what is TFIID
general transcription factor required for all Pol II transcribed genes