Ch.1:Principles of biological structure Flashcards
Describe covalent bonds; which biological molecules use these bonds? Strong or weak?
strong
two atoms share pair of electrons
DNA, proteins, sugars
What is a polar covalent bond? example?
unequal sharing of electrons that create a slight positive and slight negative charge. ex: water is dipolar with oxygen negative and hydrogen positive, creating the dipole moment
what are the non covalent bonds? strong or weak?
ionic or electrostatic, hydrogen, hydrophobic, and van der waals ; non covalent bonds are weak but collectively can be strong.
describe ionic/electrostatic bonds
opposite charges attract; like repel
what determines levels of interaction btwn molecules?
The relative strength of ionic interactions depends on the concentration of other ions in solution. For example, high salt concentrations can disrupt protein-protein interactions.
individual non covalent bonds are weak…but….
collectively can form multiple bonds so can be strong
describe hydrogen bonds; are they hydrophilic or phobic?
interaction of partially positive charged hydrogen and UNPAIRED E- OF ANOTHER (electronegative)ATOM. Either FON
describe van der waals interactions
transient dipole formed when 2 molecules are in close proximity
But, if the atoms get too close, the electron clouds will repel each other. They are irrespective of the polar nature of the molecules. These bonds are weak individually, but contribute with other noncovalent interactions to influence molecular folding as well as interactions between molecules.
describe hydrophobic interactions
interactions btwn non polar molecules; ex: when hydrophobic molecules aggregate in water. this is a critical part of cell membranes forming
describe the qualities of water within humans
70% of human mass; 45-60% intracellular and 25% extracellular/blood plasma
dipolor
dipolar nature of water leads to
formation of many low energy hydrogen bonds
water is important for not only hydrogen bonds but also ..
ionic interactions and important for hydrophobic interactions
describe an amphipathic molecule
has both polar and nonpolar regions
describe the lipid membrane and what regions are polar and non polar?
polar heads of the phospholipids and non polar tails which form the inside /hydrophobic area of the membrane
describe micelles
form with polar heads on outside facing the water and hydrophobic/nonpolar heads on the inside away from the water
proteins and folding interactions with water
proteins will fold so that hydrophobic part is inside, away from water, and hydrophilic part is outside, towards the water
ionization of water?
water ionizes to H+ and OH-
at 25 degrees, what is the molar concentration of each water ion?
multiplied together [H+][OH] = 10^-14
in pure water what is the molar concentration of each ion?
10^-7
what is the pH of the cytoplasm? acidic or basic?
7.2 (slightly basic)
define a biological buffer
a weak acid and its conjugate base that causes a solution to resist changes in pH when an acid or base is added
what tells you how strong or weak a buffer is?
ka= the dissociation constant; formula is [free H+][conjugate base]/ [undissociated acid]
the effectiveness of a buffer is determined by what? buffers work best when…
the concentration (the more present, the greater the buffering capacity), and the pH of the solution (buffers work best within 1 ph unit of their pka)
what is the equation of henderson hasselback eqn
pH=pka + log [free acid]/[undissociated acid]
what are 2 major physiological buffers? what do they each regulate?
ph of the cytoplasm is maintained by what?
carbon dioxide-bicarbonate system which manages blood ph and he phosphate system which regulates cytosolic pH
buffers: weak acids and bases
the larger the Ka…
The larger the Ka value, the more dissociation of the molecules in solution and thus the stronger the acid.
why is the pKa of bicarbonate 6.1 if the ph of blood is 7.35?
you want the buffer to work in a region where it is a most risk
solve this:
patient with blood pH of 7.03 and [co2] of 1.1 mM. Calculate the patient’s [HCO3]
9.35
define acidosis; what patient parameters should be monitored?
blood pH drops below 7.35; monitore [HC03] AND [CO2]
what makes up an amino acid? which groups are charged at physiological ph?
what type of amino acids are found in proteins
carbon, carboxyl, and amino acid and R group
at physiological pH:
COOH is deprotonated
NH2 is protonated to NH3
L (L= life)
alanine
Ala, A
Arginine
Arg, R
arrrrginine