Essential idea:

Living organisms control their composition by a complex web of chemical reactions.

Understandings:

• Molecular biology explains living processes in terms of the chemical substances involved.

– This is a reductionist approach --(breaking things down into their component parts)

– This approach has given us insights into whole organism

– However, this approach is limited because when components are combined unique and possibly unpredicatble properties arise (emergent properties)

Understandings:

• Molecular biology explains living processes in terms of the chemical substances involved.

– Below is an example of one chemical reaction that take place in the body, that is the formation of urea, which the primary constituent of urine

Understandings:• Carbon atoms can form four covalent bonds allowing a diversity of stable

compounds to exist.

Matter consists of chemical elements in pure form and in combinations called compounds

• Organisms are composed of matter

• Matter is anything that takes up space and has mass

• Matter is made up of elements

Elements and Compounds

• An element is a substance that cannot be broken down to other substances by chemical reactions

• A compound is a substance consisting of two or more elements in a fixed ratio

Sodium Chlorine Sodium chloride

An element’s propertiesdepend on the structure of its atoms

• Each element consists of unique atoms

• An atom is the smallest unit of matter that still retains the properties of an element

Essential Elements of Life

• About 25 of the 92 elements are essential to life

• Carbon, hydrogen, oxygen, and nitrogen make up 99% of living matter

• Most of the remaining 1% consists of calcium, phosphorus, potassium, iron and sulfur

Organic Compounds

• Organic Compounds are compounds containing carbon found in living things

– BUT there are exceptions are classified as NON-organic

• Carbon dioxide (CO2)

• Carbon Monoxide(CO).

• Hydrogen Carbonates (HCO3- )

Overview: Carbon—The Backbone of Biological Molecules

• Although cells are 70–95% water, the rest consists mostly of carbon-based compounds

• Carbon is unparalleled in its ability to form large, complex, and diverse molecules

• Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds

Concept 4.2: Carbon atoms can form diverse molecules by bonding to four other atoms

• Electron configuration is the key to an atom’s characteristics

• Electron configuration determines the kinds and number of bonds an atom will form with other atoms

• Remember the OCTET RULE!! All atoms lose/ gain/ share electrons so they can get 8 electrons on their outer shell

The Formation of Bonds with Carbon

• With four valence electrons, carbon can form four covalent bonds with a variety of atoms

• This tetravalence (4 valence electrons) makes large, complex molecules possible

• In molecules with multiple carbons, each carbon bonded to four other atoms has a tetrahedral shape

• However, when two carbon atoms are joined by a double bond, the molecule has a flat shape

• In molecules with multiple carbons, each carbon bonded to four other atoms has a tetrahedral shape

• However, when two carbon atoms are joined by a double bond, the molecule has a flat shapeMolecularFormula

StructuralFormula

Ball-and-StickModel

Space-FillingModel

Molecular Diversity Arising from Carbon Skeleton Variation

• Carbon chains form the skeletons of most organic molecules

• Carbon chains vary in length and shape

Length

Ethane Propane

Butane 2-methylpropane(commonly called isobutane)

Branching

Double bonds

Rings

1-Butene 2-Butene

Cyclohexane Benzene

Hydrocarbons• Hydrocarbons are organic molecules consisting

of only carbon and hydrogen

• Many organic molecules, such as fats, have hydrocarbon components

• Hydrocarbons can undergo reactions that release a large amount of energy

Combustion of Hydrocarbons

• Hydrocarbons can undergo reactions that release a large amount of energy

Understandings:• Metabolism is the web of all the enzyme-catalysed reactions in a cell or

organism.

– Enzymes are biologically synthesized proteins that speed up a chemical reaction without changing/ reacting themselves.

What is an Enzyme?

• globular proteins

• catalysts which speed up biological reactions

• unchanged by the reaction

• specific to their substrate

• active site is the position on the enzyme occupied by the substrate

• affected by temperature and pH

Organization of the Chemistry of Life into Metabolic Pathways

• A metabolic pathway begins with a specific molecule and ends with a product

• Each step is catalyzed by a specific enzyme

What is an enzyme animaiton:http://www.northland.cc.mn.us/biology/biology1111/animations/enzyme.swf

Understandings:• Anabolism is the synthesis of complex molecules from simpler molecules

including the formation of macromolecules from monomers by condensation reactions.

• Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers.

Hydrolysis vs. Condensation

Hydrolysis

• Adds water

• Breaks down polymers into monomers

• Catabolic

• Breaks down complex molecules into simpler molecules

• Example: Breaks down starch into glucose

Condensation

• Removes water

• Forms new bonds between monomers forming polymers

• Anabolic

• Forms more complex molecules from simpler ones.

• Example: glucose and fructose are bonded together to form sucrose

4 Types of Condensation (dehydration) Reactions

1. Occurs between monosaccharide and forms disaccharides and polysaccharides

2. Occurs between glycerol and fatty acids and forms monoglycerides

3. Occurs between monoglycerides and forms di- and tri-glycerides

4. Occurs between amino acids and forms polypeptides (proteins)

Condensation (dehydration) Reactionin carbohydrates

glucoseglucose Starch

glucose FructoseSucrose

Condensation reaction of amino acids to form polypeptides (proteins)

Condensation monoglycerides

4 types of hydrolysis reactions

1. Breakdown of disaccharide or polysaccharides into monosaccharide

2. Breakdown of monoglycerides into glycerol and a fatty acid

3. Breakdown of diglycerides and triglycerides into monoglycerides

4. Breakdown of a polypeptide (protein) into amino acids.

Hydrolysis of sucrose (dissacharide)

Hydrolysis of Maltose

Hydrolysis of a dipeptide

Understandings

• Life is based on carbon compounds including carbohydrates, lipids, proteins and nucleic acids.

Below is the structure of a LIPID

Ester linkage

Fat molecule (triacylglycerol)

Molecular Protein Structure

Carbohydrate structure

Nucleic acid Structure

Skills & Applications

• Application: Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized.

• Skill: Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.

• Skill: Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams.

Nature of Science

• Falsification of theories—the artificial synthesis of urea helped to falsify vitalism.