Adv. Bio Ch. 3 & 4 Test

hydrophobic

any substance that does not have an affinity for water Usually non-ionic or non-polar Major components of cell membranes

hydrophilic

any substance that has an affinity for water Usually ionic or polar Term can even be used if a substance does not dissolve: cotton towel

H20 => H+ + OH- (Simplified equation) But, we actually get OH- and H30+

chemical equation for dissociation of water

organic

compounds that contain C

aldehyde

if the carbonyl group is at the end of the C skeleton

ketone

if the carbonyl group is elsewhere

solution

mixture in which one or more substances are uniformly distributed in another substance.

hydrocarbons

organic molecules consisting of only C and H Not prevalent in organisms, but don't forget about portions of fats and cell membranes... Non-polar...hydrophobic

acid precipitation

pH more acidic than 5.6 Mainly due to sulfur dioxides and nitrogen oxides in the air as byproducts of fossil fuel burning. Particularly noticeable when spring thaw drains into areas where aquatic life are producing eggs and young. Can also affect abiotic portions of environment such as soil. Uncontaminated rain: pH about 5.6

aqueous solution

solution in which water is the solvent; universally important to living things, but not the universal solvent; measured in moles

acids

substances that increase the H+ concentration of a solution -proton donor - "low" numbers on pH scale

bases

substances that reduce the H+ concentration of a solution -proton acceptor - "high" numbers on pH scale Some bases work by creating water by combining the H+ and their OH- Some bases work by accepting the H+ AKA: alkaline

adenine & guanine

the purines

cytosine, thyamine, & uracil

the pyramidines

solute

the substance dissolved in a solution

solvent

the substance in which the solute is dissolved; dissolving agent

The addition of acids or bases in solution will disrupt the H+ and OH- balance in pure water.

How can the concentrations of H+ and OH- in pure water be disrupted?

hydroxyl group

*OH "Alcohols" Names end in -ol usually Polar *Do not confuse this with the OH- for the hydroxide ion!!!

(Organisms depend on the cohesion and adhesion of water molecules.) Water displays ADHESION.

-Adhesion is an attractive force between unlike substances. - Water molecules are not only attracted to each other, but to any molecule with positive or negative charges. -Adhesion in water is due to polarity and hydrogen bonding. -Example: water clings to paper, is also how a towel dries you

(Organisms depend on the cohesion and adhesion of water molecules.) Water is COHESIVE.

-Cohesion is an attractive force between particles of the same kind. -In water, this is due to polarity and hydrogen bonding. -Examples: water falls from the sky as raindrops (not individual molecules), water tends to bead up on the hood of your freshly waxed car, water can bulge out over the rim of a glass if you fill it carefully.

Water has SURFACE TENSION.

-Due to cohesion, in the bulk of the water, each molecule is pulled equally in all directions by neighboring water molecules, resulting in a net force of zero. -However, at the surface of the water, the molecules are pulled inwards by other water molecules deeper inside the water and are not attracted as intensely by the molecules in the air. -Thus the liquid squeezes itself together until it has the locally lowest surface area possible. -Examples: bugs that can walk on water, leaf floating on a deep puddle

Water is POLAR and individual water molecules are held together by hydrogen bonds.

-In water's covalent bonds, hydrogen and oxygen do not share electrons equally. -Because the shared electrons spend more time closer to oxygen than the hydrogen atoms, oxygen is considered electronegative. -These slight + and - charges make the molecule polar. -Polarity also causes water molecules to stick to each other and to other things. -An attraction occurs between slightly positive hydrogen atoms of one water molecule and the slightly negative oxygen atom of another water molecule. -Every water molecule is hydrogen bonded to neighboring water molecules. -A hydrogen bond is a weak bond that can easily be broken.

Water displays CAPILLARITY.

-Together adhesion and cohesion enable water molecules to move upward through narrow tubes against the force of gravity. - As the edges of a container are brought closer together, such as in a very narrow tube, the interaction of adhesion and cohesion causes the liquid to be drawn upward in the tube. -Example: water flows into a flower through its stem.

Oceans and lakes don't freeze solid because ice floats.

-Water is one of the few substances that are less dense as a solid than as a liquid. -ICE FLOATS!!! -Hydrogen bonding causes ice to expand when it solidifies; most other materials contract to solidify. -Example: If ice sank, lakes and oceans would freeze solid.

Water MODERATES TEMPERATURE on Earth

-Water stabilizes air temperatures by absorbing heat from air that is warmer and releasing the stored heat to air that is cooler. - Water must gain or lose a relatively large amount of energy for its own temperature to change because water has a high specific heat (the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree C). -Water has a high specific heat because when water is heated, most of the thermal energy that the water initially absorbs is used to break down the hydrogen bonds between the water molecules. Only after these bonds have been broken, does the thermal energy cause an increase in the temperature of water. -Water also participates in evaporative cooling to contribute to temperature stability. -Examples: All organisms must maintain homeostasis to survive. In organisms, the ability of water to absorb large amounts of energy helps to keep cells at an even temperature despite temperature changes in the environment. This property is also important to life in lakes and oceans and plays an important role in weather and local temperatures.

ions

-charged particles -When dissociation happens, the hydrogen atom leaves its electron behind and what is actually transferred is a hydrogen ion. A hydrogen ion is actually a single proton with a charge of +1. The water molecule lost a proton and is now an ion too.

functional groups

-parts of organic molecules most commonly involved in chemical reactions -"Kind of" can be considered attachments that replace an H in the C skeleton -Each behaves consistently from one organic molecule to another

fitness of the environment

Acid precipitation threatens the _________________________.

Importance of Benzene in Organic Chemistry / Biology

Alternating double bonds Extraordinary molecular stability Puts any substance possessing it into a very broad organic family known as the aromatic compounds The number of chemical structures which include the benzene ring are almost immeasurable Common products...besides oil derivatives wood preservatives Aspirin oil of wintergreen

carbonic acid

Buffer Example in the Human Body: Normally blood pH is very near 7.4 and a person cannot survive for more than a few minutes if the blood pH is <7 or >7.8 _________________ is a main blood buffer (H2CO3) It dissociates to yield bicarbonate ion and a hydrogen ion H2CO3 HCO3− + H+ Acid / Base/Hydrogen Ion H+ donor H+ acceptor *The reaction proceeds from L to R when blood pH rises (H+ falls) so that H2CO3 can release a H+ and turn into HCO3 *The reaction proceeds from R to L when blood pH decreases (H+ rises) so HCO3 can accept a H+ and turn into H2CO3

carbon

C counts for the endless diversity of biological molecules. Due to its 4 valence electrons, C usually doesn't gain or lose electrons to form ionic bonds, but rather makes 4 covalent bonds instead...TETRAVALANCE! *Don't forget about double bonds!

methyl group

Carbon bonded to 3 hydrogen atoms and something else Can affect the expression of genes and/or hormones

pH scale

Defined as the negative logarithm of the hydrogen ion concentration.

structural isomers

Different covalent arrangement of atoms

geometric isomers

Different spatial arrangements

tenfold

Each pH unit represents a ___________________ difference in H+ and OH- concentrations Ex: A solution of 3 is NOT 2x as acidic as a solution of 6; it is 1000x more acidic! When the pH of a solution changes SLIGHTLY, the actual concentration of H+ and OH- in the solution change SUBSTANTIALLY! The pH of a neutral solution is 7, with most biological fluids falling between 6-8.

buffers

Even a slight change in pH can be harmful to a cell because the chemical processes of the cell are VERY sensitive to the concentrations of H+ and OH- ions. Biological fluids resist changes to their own pH with ____________________. Substances that minimize the changes in the concentrations of H+ and OH- ions in a solution. -Accepts H+ from the solution when they are in excess and donates H+ to the solution when they have been depleted. Most can do this because they are weak acids or weak bases. Most are acid base pairs.

philic

Functional Groups Most Important in the Chemistry of Life: Hydroxyl Carbonyl Carboxyl Amino Sulfhydryl Phosphate Methyl *All are hydro__________ and thereby increase the solubility of organic compounds in water.

estrone & testosterone

Functional groups can cause big differences!

the pH scale

In any solution, the product of the H+ and the OH- concentrations is constant at 10-14 M2. Because the H+ and OH- concentrations of solutions can vary by a factor of 100 trillion or more, scientists developed _________________________.

simple organic molecules

Methane = CH4 Ethane = C2H6 Ethene = C2H4 Propane = C3H8 Benzene = C6H6

enantiomers

Mirror Images...Can be dangerous in drugs

amino group

Nitrogen bonded to 2 hydrogens N-H l H "Amines" Acts as a base by picking up a proton

carbonyl group

O double bonded to C O=C Called an ALDEHYDE if the group is at the end of the C skeleton Called a KETONE if the group is elsewhere

DISSOCIATION OF WATER MOLECULES

Occasionally a hydrogen atom shared between 2 water molecules in a hydrogen bond shifts from one water molecule to the other This is statistically rare: only 1 water molecule in every 554,000,000 is dissociated.

pH

Organisms are sensitive to changes in ______.

carboxyl group

Oxygen double bonded to a C that is single bonded to a hydroxyl group O=C-OH Hybrid of carbonyl and hydroxyl groups "Carboxylic acids" or "organic acids" Has its acidic properties due to 2 close oxygen atoms being so electronegative

phosphate group

Phosphate attached to 4 oxygen molecules One O is double bonded One O attaches the group to the C skeleton "Organic phosphates" Work in energy transfer...ATP, ADP

H30+ (Hydronium ion)

Since one water molecule gained a proton, it now has a positive charge.

OH- (Hydroxide ion)

Since one water molecule lost a proton, it now has a negative charge.

strong

Single arrows show that the reaction is unidirectional as the compounds dissociate completely when mixed with water. These acids and bases are termed __________________.

sulfhydryl group

Sulfur bonded to hydrogen -SH "Thiols" Sulfur has 6 valence electrons like oxygen does Stabilizes proteins

Straight Branched Closed rings

The Variation in C Skeletons Contributes to the Diversity of Organic Molecules: skeletons may be __________________________________.

dissociation of water

The ______________________________ is exceedingly important to the chemistry of life. H+ and OH- are highly reactive. Changes in their concentrations can drastically alter a cell's proteins and other complex molecules.

the molecular components attached to that skeleton

The distinct properties of an organic molecule depend not only on the arrangement of its C skeleton, but also on __________________________________.

isomers

The variation of organic molecules is also seen in _____________________. compounds that have the same molecular formula, but different structures and therefore, different properties Structural isomers Geometric isomers Enantiomers

HYDROXIDE ION. (OH)

The water molecule that lost a proton is now called a _____________________________.

HYDRONIUM ION. (H30)

The water molecule that the proton bonded to is now called the ________________________________.

The Nitrogenous Bases ☺

Uracil - C4H4N2O2 Thymine - C5H6N2O2 Guanine - C5H5N5O Cytosine - C4H5N3O Adenine - C5H5N5

_______________ is the solvent of life.

Water

This reaction is reversible and reaches a state of dynamic equilibrium

________________________________________________________________________________________________________________________________________________ when water dissociates at the same rate it is being reformed from H+ and OH-. At equilibrium, the concentration of water molecules greatly exceeds the concentration of H+ and OH-