THE STUDY OF LIFEBiology

Scientific Method Observation Question Hypothesis- educated guess that can be

tested Experiment-needs to be controlled only

manipulating one variable Record and analyze-be accurate and use

graphs Conclusion-you gain evidence to support

hypothesis or disprove hypothesis

Biology “study of life” Where did life come from?

A mixture of logic and magicBiosphere

○ The part of the earth in which organisms live○ Land, water, and air

Aristotle (300 BC) and etherSpontaneous Generation

Spontaneous Generation

“Recipes”Bees Dead Bull in ShedFlies Rotting MeatMiceDiscarded RagesGeese Mudding River BanksSalamanders Wood & Fire

Francesco Redi’s Experiment 1668 in Italy Used cloth cover jars that would not

allow maggots to get to meat Proved flies don’t come from rotting

meat After hundreds of years of debate,

biogenesis theory replaced spontaneous generation ideas

Biogenesis- “life comes from life”

Five Properties of Life1. Organization2. Energy (metabolism)3. Growth & Development4. Reproduction5. Response & Adaptation

OrganizationAtoms

MoleculesCellsTissueOrgansOrgan system Individual PopulationCommunitiesEcosystem

BIOCHEMISTRY

Matter, Mass, and Weight

1. Matter: An object occupies space and has mass.

2. Mass: The quantity of matter an object has.

3. Weight: The pull of gravity on an object’s total mass.

Atomic Theory All elements are composed of tiny, indivisible

particles that we call atoms. Atoms of the same element are identical while

atoms of different elements are different. Atoms can combine together in whole number

ratios. Atoms can be rearranged into different chemical

compounds by chemical reactions. Atoms of one element can NOT be changed into

atoms of different elements.

Atoms

Atom: The smallest unit into which an element can be divided and retain its characteristic properties.

One unit of an element.

Elements

Element:A substance composed only of atoms of the same atomic number.

One of more than 100 distinct types of matter that, singly or in combination, compose all materials of the universe.

Atoms: Basic structure

Made up of:

Protons (+)Neutrons

( )(Nucleus)Electrons (-)Electrically Neutral

if…Protons = Electrons

Atomic Number, Symbol, Mass

Atomic Number: The number of protons found in an atom.

Symbol: The abbreviation for an element.

Atomic Mass: Weight of an atom; approx. the sum of its protons

and neutrons.

Periodic Table of the Elements

Beryllium

Atomic Number: 4Symbol: BeNameAtomic Mass:

9.0112

4

BeBeryllium

9.0112

.

Periodic Table of the Elements

4

BeBeryllium

9.0112

Be94

Mass = Protons + Neutrons

What’s wrong with this picture?

Elements are arranged:Vertically into Groups

Horizontally Into Periods

If you looked at one atom of every element in a group you would see…

The group 2 atoms all have 2 electrons in their outer shells

Be (Beryllium) Atom

Mg (Magnesium) Atom

The number of outer or “valence” electrons in an atom effects the way an atom bonds.

The way an atom bonds determines many properties of the element.

This is why elements within a group usually have similar properties.

If you looked at an atom from each element in a period

you would see…

Each atom has the same number of electron holding shells.

An example…

The period 4 atoms each have 4 electron containing shells

K (Potassium) Atom Fe (Iron)

Atom

Kr (Krypton) Atom

4th Shell

Isotopes

1. Neutrons do not equal protons.2. More neutrons than protons.3. Unstable nucleus.4. Radioactive Isotope: Isotopes that give off

energy because neutrons peel off their unstable nucleus.

Ions

Protons do not equal electrons.

More protons than electrons = a positive charge.

More electrons than protons = a negative charge.

Na+

Compounds

Definition: Two or more elements in definite

proportions that are joined together by a chemical bond.

Two Types of Bonds:○ Ionic○ Covalent

Ionic Bonds Why do they form?

Octet Rule (Rule of Eight):Atoms tend to establish completely full outer energy levels. (K fills with 2, L and M generally fill with 8.)

Ionic Bonds: an example

Chlorine has 17 electrons.Orbital K takes the first 2.Orbital L takes the next 8.Orbital M takes 7.

Sodium has 11 electrons.Orbital K takes the first 2.Orbital L takes the next 8.Orbital M takes 1.

Ionic Bonds: an example

Chlorine needs one more electron to fill its outer shell with 8 electrons. (Octet Rule)

If sodium gives up one electron it will have eight in its outer level.

Ionic Bonds: an exampleChlorine:17 protons18 electronsWhat’s its charge?-1 (negative ion)Sodium:11 protons10 electronsWhat’s its charge?

+1 (positive ion)

What do you think happens next?

Ionic Bonds: opposites attract

The sodium atom and the chloride atoms are attracted toward one another because of their opposite electrical charges.

The combination makes sodium-chloride,

abbreviated NaCl,commonly known as salt.

Ionic Bonds Definition:

An attraction between ions of opposite charge.

These bonds are relatively weak and will easily dissolve in water.

Covalent Bonds Definition:

A chemical bond formed by the sharing of one or more pairs of electrons.

These bonds can be very strong. Most of the structures in the body are

made using these types of bonds.

Molecules

Definition:A group of elements held together by covalent bonds.

Example:WaterTwo hydrogens and one oxygen share two pairs of electrons.

Covalent Bonds, cont.

Why do hydrogen and oxygen want to share?

Answer:Each wants to fill its outer shell with electrons.

Hydrogen fills with 2.Oxygen fills with 8.

Covalent BondsMany types of covalent bonds

Single covalent:shares one pair.

Double covalent:share two pairs.

Triple covalent:share three pairs.

Chemical Reactions Equation:

A formula that describes what happens during a chemical reaction.

H2

+ O2

H2O + O• Balanced Equation:

The elements on the left side of the equation are the same as those on the right.Notice! States of matter (liquid, solid,

gas) may change during a reaction.

Chemical Reactions: Terms

Activation Energy (Energy of Activation):The energy needed to make a reaction occur.

• Reactant- The chemicals before reaction

• Product- The chemicals after reaction

BIOLOGY

WATER,ACIDS, AND BASES

Water

The Cradle of Life:1. The Universal Solvent.2. The Polarity of Water.

Solutions

Solution:A homogeneous mixture of the molecules of two or more

substances.

Ex. Water and glucose mixture.

Solvent

Solvent: Medium in which a substance is dissolved (water).

Water is known as the universal solventbecause most of the chemical reactionsnecessary for life take place in water (i.e.water is the solvent).

Solutes

Solutes: A compound dissolved in some solution.

Ex. The glucose in the waterglucose mixture.

Polarity

For example:

In a water molecule, one oxygen atom shares electrons with two hydrogen atoms.

Do they share equally?

Polarity, cont.

Oxygen and Hydrogen do not share electrons equally.

Oxygen is more electronegative (it attracts electrons more heavily) than hydrogen.

Polarity, cont.

The result is that the electrons shared by oxygen and hydrogen actually spend more of their time nearer the oxygen atom. This gives the oxygen a slightly negative charge and leaves hydrogen with a slightly positive charge.

+-

Note: The charges are only partial. (i.e. not as large as a full proton or electron would be.

The Polarity of Water

1. Water bonds (hydrogen bonds) to itself.

2. Water bonds to other molecules.3. Water will group non-polar molecules.4. Water is a powerful solvent.

Hydrogen Bonds1. The positive or negative end of water will be

attracted to other polar molecules.2. Weak bonds3. Usually last only 1/100,000,000,000 sec.,

but their cumulative effect can be great.

Water Clings

Cohesion: Water attracted to water.

Adhesion: Water attracted to other polar molecules.

Capillary Action – water will “climb” by adhering to a surfaces electrical charges.

Adhesion

Hydrophobic: Water-fearingWater tends to form hydrogen bonds. When it mixes with non-polar molecules, it tends to shun them and instead cling to other water molecules.

Hydrophilic: Water-loving.Polar compounds will form hydrogen bonds with water. This breaks ionic bonds, dissolving the compound.

WATER

It’s reactions…

Acids and Bases

pH

1. A measure of the relative concentration of hydrogen ions in a solution.

2. Values range from 0 to 14.3. Less than 7 is an acid.4. More than 7 is a base.

Acids

1. A substance that causes an increase in the concentration of H+ ions.

2. Tastes sour.3. Tingles the skin.

Bases

1. A substance that causes a decrease in the relative concentration of H+ ions.

2. Also called alkaline.3. Tastes bitter.4. Sometimes slippery or slick feeling.

Chemical Reactions

Catalyst-substance that speed up chemical reaction

Enzyme-is a protein that acts as a biological catalyst

Elements important for life. Oxygen (65% of body by weight) Carbon (18%) Hydrogen (10%) Nitrogen (3%)

(N.O.C.H.)

Elements in Human Body

Oxygen (65%) Carbon (18%) Hydrogen (10%) Nitrogen (3%) Calcium (2%) Phosphorus

(1%)

Other 1% Potassium Silicon Aluminum Iron Sodium Chlorine more...

Organic Compounds

1. Pertaining to living things.

2. The chemistry of compounds containing carbon.

Building Macromolecules Monomer-smaller unit of large

compounds Polymers-monomer that join together to

form macromolecules

Organic Compounds or Macromolecules

4 Types of Organic Compounds:1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids.

Carbohydrates

Three types:1. Monosaccharides2. Disaccharides3. Polysaccharides

Monosaccharides

One sugar molecule.

Carbon Backbone: Carbon atoms line up near the center of the molecule and other atoms attach to them.

Formula for Simple Sugars: C6H12O6

Monosaccharides

Three basic types:1. Glucose (general sugar)2. Fructose (fruits)3. Galactose (milk)

Isomer: Alternative forms of a molecule that

have the same formula.

Polysaccharides

Many monosaccharides bonded together.(Storage sugars.)

Three types:1. Starches (plants – potato!).2. Cellulose (structure – plant cell walls).3. Glycogen (animal storage).

Functions of Carbohydrates

1. Energy source (glucose).2. Long-term energy storage (starch,

glycogen).3. Structure (cellulose).

Organic Compounds

4 Types of Organic Compounds:1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids.

Lipids

Five types:1. Fats2. Oils3. Waxes4. Phospholipids5. Steroids

Lipids

Functions: Long-term energy storage (fats, oils). Insulation (fat). Protection (waxes waterproof or keep in

water). Cell membrane structure (phospholipids). Control of body functions (steroids).

Organic Compounds

4 Types of Organic Compounds:1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids.

Proteins

Types:1. Amino acids.2. Dipeptides.3. Polypeptides.

Proteins

Amino Acids: Building blocks for all proteins. 20 total. Link together to form “peptide” bonds.

Proteins

Functions: Movement Structure Regulation (catalysts, enzymes) Transport Nutrition Defense

Proteins(catalysts and enzymes)

Catalyst:Substances used in small amounts which speed up chemical reactions without themselves being affected by the reaction.

Enzyme:Proteins that function as catalysts.(overhead)

Organic Compounds

4 Types of Organic Compounds: Carbohydrates Lipids Proteins Nucleic Acids.

Nucleic Acids

Types: DNA (deoxyribonucleic acid)

RNA (ribonucleic acid)

Functions of Nucleic Acids

Information storage (DNA)

Information transfer (RNA carries genetic information from DNA to ribosomes)