Water, Buffers, And Weak Interactions Flashcards
Why do lipids separates
Non polar lipids have a stronger affinity for _____
polar lipids have a stronger affinity for ____
Due to diff affinity of non polar and polar components
Mobile phase (travel faster)
Stationary phase
What causes hydrogen bonding
Electronegativity differences
What is a hydrogen bond donor and acceptor
Donor: the this attached to the H thats h bonding
Acceptor: the thing that the h is interacting with
How long is a hydrogen bond
How long is the covalent bond between the H and its electronegative atoms
When is hydrogen bond the strongest
3 Angstroms (donor to acceptor distance)
2.0 (h to acceptor distance, h bridge distance)
0.9 angstroms
When the angle at the hydrogen is 180
What type of interaction is a hydrogen bond
What does it form
A noncovalent
Forms a hydrogen bridge
What is a van der waals interaction
When the charge isn’t evenly distributed around the molecule (not symmetric)
The partial positive and negative charges interact with each other
What is the van der waals contact distance?
The distance between the two molecules where the attraction is greatest
What happens when molecules are too close? Too far?(infinity)
Repel if close
No interaction if far (NRG =0)
What are ionic interactions
Attraction of oppositely charge ions/ atoms
What is meant by a high dielectric constant
Water shielding the separate postive and negative charges of the salt so the the salt can dissolve
What is Coulomb’s law
What happens if r or D increases
E=kqq/Dr
D=dielectric constant
R= distance between charges
E decreases
What is the hydrophobic effect
Give example
An entropic process where the nonpolar hydrophbic molecules group together to decreases the interaction with water
Can have different combos of chafe, so diff entropy
Ex. Lipid bilayer
What type of bond has the highest NRG
Which type of interactions are similar in energy
Covalent: more stable and harder to break
Noncovalent (ionic, h bond, van der)
Why are noncovalent interaction weaker
What can they do
Weaker because they allow formation and breakage
The noncovalent interactions can sum up
Kw is for
Ka is for
Water
Acid
What happens to ph when acid is added to water
What about sodium acetate
What does this mean
Ph imeaditely drops
Ph drops but has a range where it drops more slowly
So sodium acetate acts as a ph buffer between 3.8 and 5.8 ph
What are the mono protic acids and their ka
Acetic acid (ka 1.74x10-5)
Ammonium ion (5.62X10-10)
What are the di protic acids and their ka
When are the a good buffer
Carbonic acid
Bicarbonate
Glycine, carboxyl (1.3-3.3 ph)
Glycine, amino (8.6-10.6)
What are the triprotic acids
Phosphoric acid
Dihydrogen phosphate
Monohydrogen phosphate
Why are biological systems buffered
Because if you lose or add a proton to the systems the properties of the system change
What is buffer capacity
The max amount of h that can be added until it can’t resist ph change anymore
Henderson hassle balch equation
Ph = pka + log (base/acid)
In a triphosphate system, which form would be important for buffering a living cell
The one at ph around 7
What is a major buffer in blood and what plays a role in the buffering system
Carbonate,
Co2 plays a role in maintaining the Ph at 7.4