life at cellular level 4 Flashcards
functions of water in the body
1-transports and dissolves substances round the body
2-takes place in chemical reactions
3-bathes cells
4-dissapates heat
hydrogen bonding features
forms between H and F,O,N
it maintains the structure of ice
it is present in hydrophilic substances e.g. aldehydes, ketones, sugars…
it is strongest when 3 atoms lined up
weaker when atoms are at an angle with each other.
how do polar substances(which are hydrophilic) e.g. NaCl react with water?
NaCl dissolves in water. Na reacts with the delta negative end of the water molecule.Cl reacts with the delta positive end of the water molecule.
how are CO2 and 02 transported round the body
not polar so not very soluble in water.
O2 transported by haemoglobin
C02 just floats round the body
protein interaction and water integration
1-initially ordered water reacts with substrate and enzyme separately
2-as substrate and enzyme get closer, water becomes disordered and enzyme and substrate interact.
3- enzyme-substrate complex is maintained by h-bonding, ionic bonding and hydrophobic interactions
how do molecules which are not water soluble move within the body
1-hydrophobic molecules maintain a very ordered structure to prevent interrupting the H-bonding in the water around them. water cages.
2-lipids- hydrophilic part of the lipid reacts with water to increase disorder or particles.
3-proteins fold on themselves so hydrophobic section is folded away. hydrophilic reactions take place between other parts of protein and water.
3-hydrophobic lipids are transported in chylomicrons
Liposomes
form when many phospholipids are dissolved in water.
very controlled environment.
water dissociation
partial charges on water means it dissociates weakly into H+ and OH-.
H2O –> H+ +OH-
conc of H20 is constant so can be taken as equal to 1.
Kw = [H+][OH-] = 10^-14
-log[H+]= -log[OH-]= 7
ph of water is neutral
ph of acids and bases
acids have a high conc of H+
bases have a higher conc of OH-
strong acids and bases dissociate completely
weak acids and bases only dissociate slightly.
weak acids and bases are used as buffers
importance of weak acids and bases.
acid: proton donor
base: proton acceptor.
acid and base: conjugate acid-base pair.
in biological system ph must stay the same. if it did not the charge on proteins would change which in turn would change the shape and function of the protein. buffers help maintain this environment.
henderson-hasselback equation and when do buffers work best
helps determine the amount of conjugate weak acid or base in a solution.
pH = pKa + log ([A-]/[HA])
buffers work best when conc of HA is equal to A- so when ph=pKa
which buffer systems are important in the body
phosphate and bicarbonate
H2PO4^- —-> H+ +HPO4^2-
H2CO3—> H+ +CO3^-
what are the buffering features of blood
contains HCO3- which prevents fluctuation of ph levels despite high acid content in the blood. metabolic acidosis.
