Ap bio 2

Water is a polar molecule

Unequal sharing of electrons between O and H. Hydrogen bonds. Slightly negative O attracted to slightly positive H of nearby molecule. H2O can form up to 4 bonds.

Hydrogen bonds

Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic atom in another molecule.

Four emergent properties of water

cohesive behavior, ability to moderate temperature, expansion upon freezing, versatility as a solvent

1.) Cohesive behavior

Cohesion refers to water molecules binding to other water molecules. Surface tension, measure of how difficult it is to break/stretch the surface of liquid. Adhesion of H2O to vessel walls counters pull of gravity. Transpiration, movement of H2O up plants. It clings to each other by cohesion and to xylem tubes by adhesion.

Transpiration

Evaporation of water from the leaves of a plant

Cohesion

Attraction between molecules of the same substance

Adhesion

An attraction between molecules of different substances

surface tension

A measure of how difficult it is to stretch or break the surface of a liquid

2) Moderation of Temperature

Thermal energy/heat: total amount of KE in system. Temp: measure intensity of heat due to average KE of molecules. Water has a high specific heat. Temp changes less when it gains or loses heat. Warmer coastal areas? Creates stable marine and land environments. Resists change. 1 calorie.

Evaporative cooling. High heat of vaporization. Molecules with greatest KE leave as gas. Cool plants, human sweat.

Vaporization

The change of state from a liquid to a gas

evaporative cooling

The process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state.

specific heat

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius

thermal energy

Heat energy, amount of KE

Temperature

A measure of the intensity of heat in degrees, reflecting the average kinetic energy of the molecules.

3. Expansion Upon Freezing

Insulation by ice, less dense, floating ice insulates H2O below. Life exists under frozen surface, ice is a solid habitat.

insulation by ice

one of the emergent properties of water; occurs because the liquid form of water is more dense than the solid form of water (ice)

4.) water = solvent of life

Solution: liquid, homogeneous mixture of 2+ substances. Solvent, dissolving agent, solute, dissolved substance. Water is versatile. "Like dissolves like". Hydrophilic and hydrophobic.

Solution

A homogeneous mixture of two or more substances

Solvent

A liquid substance capable of dissolving other substances

Solute

A substance that is dissolved in a solution.

Hydrophilic

water loving, polar, ions, cellulose, sugar, salt, blood.

Hydrophobic

Water fearing, repel it, non polar, oils, lipids, cell membrane.

Acids and Bases

neutralize each other

Acid

A substance that increases the hydrogen ion concentration of a solution.

Base

A substance that decreases the hydrogen ion concentration in a solution.

Most biological fluid pH

6-8

pH scale

measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14. Below 7 is acidic above is basic.

pH equation

pH = -log[H+]

Buffers

weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH. Minimizes change in concentration of H and OH in a solution. Keep blood at pH 7.4 ish. If blood drops to 7 or up to 7.8 death. Carbonic acid bicarbonate system, important buffers in blood plasma.

carbonic acid

a very weak acid formed in solution when carbon dioxide dissolves in water.

bicarbonate system

Sodium bicarbonate (NaHCO3)- converts a strong acid into a weak acid

Carbonic acid (H2CO3)- converts a strong base into a weak base

ocean acidification

decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels

Cohesion

Polar, h-bond, like-like, gravity, plants, trees.

Adhesion

H-bond, unlike-unlike, plants in xylem, blood in veins.

Surface tension

Diff in stretch, break surface, h-bond, bugs on water.

specific heat

Absorbs and retains E, h-bonds, ocean mod temp, protect marine life.

Evaporation

Liquid to gas, KE, cooling, homeostasis

kinetic energy

energy of motion

Homeostasis

process by which organisms maintain a relatively stable internal environment

Universal Substance

Polarity ionic, h-bond, good dissolver, solvent.

Bonds determine shape

In any reaction: mass, energy, and charge are conserved. And shape is very important to bio. Structure and function are always related. Not all bonds are created equal.

Energy interacts with atoms in different ways

Energy holds electrons to the nucleus. When atoms absorb energy, electrons are moved to higher energy levels. The movement back to lower energy levels releases energy as EM radiation.

Atom

The smallest fundamental unit of matter: there are 120 kinds of atoms or elements. Biology focuses on: CHON: 10 minor and 30, 50 trace elements.

Polarity

The unequal sharing of electrons in a covalent bond. Leads to unequal distribution of charge in the molecule.

All chemical reactions result in

The breaking and forming of bonds.

Bonds determine shape

Polar molecules are attracted to other polar molecules.

Hydrogen bonds

The strongest attractions between the most polar molecules.

Electrons are negative

Electron orbitals and electron cloud

Nucleus

Protons positive

Neutrons neutral

A goiter comes from too little

Iodine in the diet

Atoms bond

Bonding is accomplished by electrons interacting between atoms due to valence considerations. 2 major kinds.

Ionic: transfer of electrons not many possible combos, kinda boring.

Covalent: sharing of electrons functionally infinite combos. All important biological molecules are covalently bonded.

High specific heat

How much is absorbed or released before an increase or decrease in temp: j/g C

Water: 4.18

Ethanol: 1.24

Iron: 0.449

Ice floats

Solid water is less dense than liquid water. Water is needed for life. A great solvent.

Earth is unique in its amount of liquid water

The chemistry of life is a solution based chemistry. The majority of any organism is water. Water is one of the few substances that exists in all three phases at normal terrestrial conditions. 97% saline oceans, 3% fresh water. Lakes 87%, swamps 11%. 30.1% ground water, other .9% 68.7% icecaps and glaciers.

Water's unique properties.

Due to its polarity and resulting hydrogen bonds.

Cohesion: sticking together

Adhesion: sticking to other things

Water is both. Cohesiveness gives a very high surface tension. Transpiration: movement of water through trees. Cohesion water to water and adhesion to xylem.

High specific heat. Water as temp. Buffer. Evaporative cooling.

Water is a great solvent

No universal solvent but comes close. The "hydrogen shell", surrounding something to dissolve.

Water dissociates

Because it's so polar, water can easily break apart. Produces hydronium and hydroxide ions. In pure water, the concentration of these ions is equal: acids donate protons, bases accept protons.

pH: measure of acidity.!

Biological systems can only tolerate a narrow range of pH.

Extreme variations have bad effects at all levels of organization.

Carbon

Isomers are molecules with the same molecular formula but different structures. Any molecule more complex than propane has at least one isomer. Isomerism is another emergent property.

Isomerism

Abundant, versatile.

Carbon is tetravalent. It makes four bonds to get stable. Infinite variety.

3 kinds of isomers.

Idk

Vitalism: belief in a life force

Mechanism: theory that there is nothing special about how life is built:

Miller: stimulates early earth conditions, produced hydrocarbons, amino acids.

Kinds of isomers

Structural: same formula, diff order.

Cis-trans: same formula, diff positioning around a double bond.

Enantiomers: same formula, mirror image positioning around a central carbon. Tend to use only one of two forms.

All cells use d-sugars and l-amino acids:

Functional groups modify

The properties of organic molecules