Properties that distinguish living organisms from the non-living, inorganic world

·         Order

·         Regulation, homeostasis

·         Energy processing

·         Evolutionary adaptation

·         Growth and development

·         Response to the environment

·         Reproduction

 What, fundamentally, do we mean by this thing called science?

·         “to know”

·         Way of trying to learn how the physical world works

·         Reality based

·         Systematized, methods

·         Search for explanation and information

The Scientific Method

The process of scientific inquiry

1)      observations

2)      questions

3)      formulate testable hypothesis

4)      make a prediction (if…then)

5)      test prediction (further observations and experiments)

6)      results (either support or falsify hypothesis)

      can never provide final absolute proof

A well designed scientific experiment has...

·         Adequate controls, investigates a single variable at a time, large sample sizes, and is replicated, or the experiment is repeated to be sure the results are reproducible from trial to trial.

                                                 Proton

·         Subatomic particle with a single, positive, electrical charge found in the nucleus of an atom.

·         # of protons = characteristic of an element, same as # of electrons

·         Mass à heavy, about 1.7 x 10^-24

·         Charge à +1 (electrically charged)

Neutron

·         Subatomic particle having no electrical charge found in the nucleus of an atom.

·         Mass à heavy, 1.7 x 10^ -24

·         Charge à 0 (electrically neutral)

Electron

·         Subatomic particle with single negative electrical charge. One or more electrons move around the nucleus of an atom.

·         # of electrons = # of protons

·         Mass = light, 1/2000 that of a neutron or proton

·         Charge = -1 (electrically charged)

Element

·         Simplest kind of matter that can exist, any substance that cannot be broken down to any other substance by chemical reactions.

Ex. Oxygen, Carbon, Iron

Mass Number

Sum of the number of protons and neutrons in an atom’s nucleus. 

Atomic Number

The number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the elemental symbol.  

Isotopes

·         One of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass.

·         Unstable = gives off energy as radioactivity.

Electron Shells

·         correspond to energy levels

·         the outermost, or valence shell, determines the tendency of an element to form chemical    bonds.

·         An energy level of electrons at a characteristic average distance from the nucleus of an atom.

Compound

 a substance consisting of two or more different elements combined in a fixed ratio. 

Molecule

2 or more atoms held together by covalent bonds.

Atom

the smallest unit of matter that retains the properties of an element. 

Nucleus

(1) an atom’s central core, containing protons and neutrons. (2) the chromosome-containing organelle of a eukaryotic cell. (3) a cluster of neutrons.

Ion

  an atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.

Cation

a positively charged ion

Anion

a negatively charged ion

Chemical Bond

An attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.  

Polar Covalent Bond

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

·         (LOOK FOR O & N!)

·         HYDROPHILIC

Non Polar Covalent Bond

electrons are shared equally between two atoms of similar electronegativity.

·         HYDROPHOBIC

Hydrogen Bond

weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.

Covalent Bond

a sharing arrangement

Ionic Bond

resulting from the attraction between oppositely charge ions.

·         WEAK in water, water soluble.

Cohesion 

the binding together of like molecules often by hydrogen bonds.the way in which water beads up on a waxy surface.  

properties of water

high capacity for temperature moderation(due to high specific heat)

high capacity for evaporative cooling

ice floats b/c water is less dense as a solid

The properties of water as a solvent

good solvent for POLAR solutes

"universal solvent" 

BAD solvent for NONPOLAR solutes such as oils

water molecules have greater attraction for each other

Acid

compound that adds hydrogen ions when dissolved in water (H+) increses ion concentration of a solution.

Base

reduces hydrogen ion concentration of a solution

pH scale

0 = Very Acidic

7= Neutral

14 = Basic

Buffer

a substance that consists of acid and base forms in a solution that minimizes changes in pH when extraneous acids or bases are added to the solution 

Structural Isomers

have same molecular formula but differ in the covalent arrangements of their atoms

geometric isomers 

one of several compounds that have the same molecular formula and covalent arrangement but differ in the spatial arrangements of their atoms owing to the inflexibility of double bonds. 

Enantiomers

one of two compounds that are mirror images of each other.

functional groups

reactive groups of atoms that confer certain chemical properties. 

Hyrdroxyl Group

  a.       Structure: (-OH) a hydrogen atom is bonded to an oxygen atom.

b.      Compound: Alcohols (usually names ending in –ol)

c.       Functional Properties:

                                                              i.      Is polar as a result of the electrons spending more time near the electronegative oxygen atom.

                                                            ii.      Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars.

Carbonyl

a.       Structure: (=CO) carbon atom double bonded to a oxygen atom.

b.      Compound: Ketones – if carbonyl group is within a carbon skeleton.

Aldehydes – if at the end of carbon skeleton.

c.       Functional Properties:

                                                              i.      A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal.

                                                            ii.      These two groups are also found in sugars, giving rise to 2 major groups of sugars, aldoses and ketoses.

a.       Structure: (-COOH) oxygen atom double bonded to a carbon atom that is also bonded to an –OH group.

b.      Compound: Carboxylic acids, or organic acids

c.       Functional Properties:

                                                              i.      Has acidic properties (is a source of hydrogen ions) because covalent bond between oxygen and hydrogen is so polar.

                                                            ii.      Found in cells in the ionized form with a charge of 1 – and called a carboxylate ion.

a.       Structure: (-NH2) nitrogen atom bonded to two hydrogen atoms.

b.      Compound: Amines

c.       Functional Properties:

                                                              i.      Acts as a base; can pick up an H+ from the surrounding solution (water in living organisms).

                                                            ii.      Ionized, with a charge of 1+, under cellular conditions.

Sulfhydryl

a.       Structure: (-SH or HS-) sulfur atom bonded to hydrogen atom.

b.      Compound: Thoils

c.       Functional Properties:

                                                              i.      Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure.

                                                            ii.      Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair.

a.       Structure: (P) phosphorus atom is bonded to 4 oxygen atoms; 1 oxygen is bonded to the carbon skeleton; 2 oxygens carry negative charges.

b.      Compound: Organic phosphates

c.       Functional Properties:

                                                              i.      Contributes negative charge to the molecule of which it is a part.

                                                            ii.      Has the potential to react with water, releasing energy.

Polymer

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Condensation Reaction > Dehydration Reaction

A reaction in which two molecules are covalently bonded to each other through loss of a water molecule

Hydrolysis Reaction

Chemical process that splits molecules by the addition of water, functioning in disassembly of polymers and monomers.

Carbohydrates

o   Sugars or polymers of sugars

o   Transport or store energy

o   Structure

o   Hydrophilic – water soluble, polar

Monosaccharides

o   Glucose, fructose, diverse (many isomers)

Disaccharides