UNIT 2-BIOCHEM

What are micelles?

clusters of lipid molecules

hydrogen bonding in water is?

cooperative

What are strong bonds found in biomolecules? ______ bonds are weak but contribute to structure, stability, and function

covalent bonds, non-covalent bonds

When the hydrogen bond is a straight line you get? when the hydrogen bond is bent you get?

strong H-bond, Weaker H-bond

The attraction between the partial electric charges is ______ when O, H and O atoms are aligned in a _________

stronger, straight line

The equilibrium of the ionization of water is?

strongly to the left

In the ionization of water which direction is the equilibrium shifted toward?

strongly to the left, hydrogen bonds form quickly, water is more stable

Lipid molecuels disperse in the solution- nonpolar tails of each lipid molecues is?

surrounded by ordered water molecules which decrease the entropy of the system

What does the hydrophobic effect refer to?

the association or folding of nonpolar molecules in the aqueous solution.

The elecronegativity of the oxygen atom induces?

a net dipole moment

What are the hydrogen acceptors in biomolecules? What are the hydrogen donors in biomolecules?

acceptor-oxygen or nitrogen donor- electronegative atom

When is the buffering capacity of a buffer at its maximum?

acid/anion system is greates at pH=pKa

What is the relative [H+] in an acidic, neutral, and basic solution?

acidic-proton is high neutral-proton is equal to OH- basic-proton is low

What does pKa measure?

acidity pKa= -log Ka

phosphatidylcholine is an example of __________ molecue as it has both _____ and _____ regions in its structure

amphipathic, polar (hydrophilic) and non-polar (hydrophobic)

What are van der waals interactions?

Attractive forces that depend on the polarity. Repulsive forces depend on the size of the atom. There are weak interactions between the molecules and asymmetric distribution.

What is a micelle?

Clusters of hydrophobic groups are sequestered from water, hydrophilic ends associated with water, phospholipid bilayer.

What is the role of water as a reactant?

-Hydrolysis of ATP and ADP and Pi.- releases energy § Exergonic -Carbonic anhydrase CO2 + H2O <-> HCO3- + H+ § Endergonic

What is the importance of van der waals interactions?

-determines steric complementarity -stabilizes biological macromolecules -facilitates binding of polarizable ligands

Effect of extracellular osmolarity: -If the cell is in isotonic solution then? -if the cell is in hypertonic solution then? -if the cell is in hypotonic solution then?

-no net water movement -water moves out and cell shrinks -water moves in, creating outward pressure; cell swells, may eventually burst

the attractive force (london dispersion) depends on? the repulsive force (steric repulsion) depends on? Which dominates at longer distances?

-polarizability -size of atoms -attractive dominates at longer distances

The hydrophobic effect is one of the main factors behind?

-protein folding -protein-protein association -formation of lipid micelles -binding of steroid hormones to their receptors

In what chemical form does a proton exist in solution? why can protons hop? what is the effect of this in terms of speed of proton movement in an aqueous solution?

-proton exists in a hydronium ion -they are able to hop bc they ahve the ability to form hydrogen bonds -the speed of proton movement is extremely fast becasue of the presence of protons

Why can some biomolecues act as buffers?

-they can give/accept protons -ionizable groups -amino acids examples: phosphate, histidine, bicarbonate

the pH and pOH must always add up to?

14

in neutral solution, [H+]=[OH-] and the pH is?

7

What are hydrophobic interactions?

A force that brings the nonpolar groups together. Clustering of non-polar groups drives entropy

What is an amphipathic molecule?

Has a polar and non-polar part like membranes

what is a hydrophobic group?

Hates water, nonpolar, does not dissolve in water

The relationship between pH and the concentration of conjugate acid and conjugate base is described by?

Henderson and hasselbach equation

What is a hydrogen bond?

Hydrogen bonds are weak. It is a bond between hydrogen and oxygen or hydrogen and nitrogen. Hydrogen is the donor. It is an electronegative atom.

if [H+] is 2 X 10^-3 mol/L in an aqueous solution, calculate [OH-] of the solution.

Kw= [H+][OH-] 1 X 10^-14 M^2 = 2 X 10^-3 M [OH-] 1 X 10^-14 M^2 / 2 X 10^-3 M = [OH-] 0.5 X 10^-14 X 10^3 = [OH-] 5 X 10^-12 M = [OH-]

What is the ionic product of water?

Kw=Keq (H2O)= [H+][HO-]= 1 X 10^-14 M^2 pH

What is a hydrophilic group?

Loves water, polar or charged, dissolved in water

What is an isotonic solution?

There is no net movement, equilibrium is reached.

What is alkalosis?

Too much base in the blood, pH above 7.4

What is proton hoping?

Transfer of protons from hydronium ions. It happens in the hydronium ions. Interchangeable covalent and hydrogen bonds which allows for fast mobility of protons.

What are weak interactions between all atoms, regardless of polarity?

Van Der Waals interactions

_________ interactions involve weak interatomic attraction between two uncharged atoms resulting from transient asymmetry in the electron clouds around interacting atoms. Such interactions have two compounds _______ and _________

Van Der Waals, attration and repulsion

What is a hypotonic solution?

Water moves into the cell, osmolarity of the cell is lower than outside the cell, cell will burst

What is a hypertonic solution?

Water moves out of the cell, osmolarity of cell is much higher than outside the cell. Cell will shrink.

What are buffers?

Weak acids with a conjugate base. Acetic acid-acetate, phosphate-histidine, bicarbonate-carbonate

High _______ of water reduces attraction between oppositely charged ions allowing strong electrostatic interactions between ______ of ______ ions and water molecules. This in turn _______ the entropy and weakens the crystal lattice.

dielectric concentration, solulated or ionized, increases

What is an electrostatic interaction between uncharged, but polar molecules?

dipole interactions

Entropy of water increases as ordered crystal lattic is?

dissolved

concentrations of participating species in an equilibrium process are not independent but are related via the?

equilibrium contant

nonpolar portions of the amphipathic molecule aggregate so that?

fewer water molecules are ordered

Water is a _________ solvent for charged and polar substances

good solvent -examples: amino acids & peptides, small alcohols, and carbs

up to 4 H-bonds per water molecule give it?

high boiling point, high melting point, large surface tension

Why are non-polar molecues poorly soluble in water?

highly ordered which means entropy is low, thermodynamically unfavorable

unique properties of water such as high melting and boiling point are due to?

hydrogen bonds

Water can serve as both a? due to?

hydrogen donor and acceptor, due to dipole nature

Water can serve as both ____ and ________ due to its ____ nature?

hydrogen donor, hydrogen acceptor, dipole nature

________ bonds stabilize Watson and Crick base pairing while ________ bonds stabilize stacking of purine and pyrimidine bases.

hydrogen, van der waals

protons do not exist free in solution. They are immediately hydrated to form ___________. This is a water molecule with a proton associated with one of the non-bonding pairs. they are _______ by nearby water molecules. The colvalent and hydrogen bonds are interchangeable. This allows for a ________ of protons in water via "proton hopping"

hydronium ions, solvated, extremely fast mobility

binding sites in enzymes and receptors are often _______.

hydrophobic

Aggregation of non-polar groups in aqueous solution is called the ________. It is driving force of protein folding, protein-protein interactions, formation of micelles and hormone receptor interactions

hydrophobic effect

What is a complex phenomenon associated with teh ordering of water molecules around nonpolar molecules

hydrophobic effect

ligand binding sites can bind __________ and ligands such as steroid hormones

hydrophobic substrates

all hydrophobic groups are sequestered fsrom water;ordered shell of H2O molecules is minimized, and entropy is _______

increased

What is an electorstatic interaction between permanently charged species, or between the ion and a permanent dipole?

ionic interactions

hydrophobic effect favors?

ligand binding

Why are nonpolar molecuels poorly soluble in water?

low entropy is thermodynamically unfavorable, thus hydrophobic solutes have low solubility

In these structures called _______ the hydrophobib groups are sequestered from water and hydrophilic groups are oriented outwards to interact with the aqueous medium. This results in ____ entropy

micelles, high

what are buffers?

mixtures of weak acids and their conjugate base

what is the polarity of the following? Nitrogen, Oxygen, carbon dioxide, ammonia, hydrogen sulfide

nitrogen- non polar oxygen-non polar carbon dioxide-non polar ammonia- polar hydrogen sulfide- polar

Water is a poor solvent for _______ molecules such as ______

non-polar, aliphatic chains

buffer resist change in?

pH

What is the Henderson and Hasselback equation?

pH = pKa + log [A-]/[HA]

buffering capacity of acid/anion system is greatest at?

pH=pKa

Water is a ______ molecule?

polar

Water is a good solvent for _____ molecules such as _____ and ________

polar, glycose and carbohydrates

What is a ____ molecule in which oxygen atom carries a _____ charge and hydrogen atoms have a ____ charge

polar/dipole, negative, positive

Water is a ________ solvent for non polar substances?

poor solvent

Water is a critical determinant of the structure and function of?

proteins, nucleic acids, and membranes

What are the products of ionization of water?

proton (H+) and a hydroxide ion (OH-)

dissociation of water is a?

rapid reversible process

Protons generated from the ionization of water are ___________ and ________ with other molecules

rapidly hydrated via proton hopping and hydrogen bonding

stronger the acid, ________ its pKa value stronger the base, _________ its pKa value

smaller, larger

If pH of diet soda is 3.0, then it's [H+] relative to blood (pH: 7.4) is approximately

solution A pH=3 soultion B pH=7 10^-3 X 10^7 = 10^4 the first solution has 10,000 times more H+ than solution B

What is pH?

the negative lagarithm of the hydrogen ion concentration pH= -log[H+]

Water bound to proteins is essential for?

the proteins functions

Water acts as a powerful reactant in hydrolytic reactions and drives _________ and __________

thermodynamically unfavorable processes, and CO2/HCO3 buffering system

What is acidosis?

too much acid in the blood, pH below 7.4

hydrogen bonding of water imparts its _______

unique properties

What has an attactive (dispersion) and repulsive (steric) component?

van der waals interactions

hydrogen bonds between neighboring molecules are?

weak (easily broken)

Hydrogen bonds are often shown as 3 lines and are _______ and ________ than covalent bonds (length and strength)

weaker and longer