Organic Basis of life

Chapter 3

Organic Compounds

• Carbon based molecules– Readily form covalent bonds

• Review electron shell model

– Hydrocarbons are nonpolar, containing only C and H• Dependent upon

– Structural size • CH4, C6O12H6, CO2 different number of carbon atoms

– Shape • Can form chains, branches, or rings• Isomers: same chemical formula, but different atomic arrangement

– Functional group• Creates specific structural and functional properties

IsomersC4H10

C4H8

• Be able to recognize/identify each

• Other groups, but don’t need to know

Carbohydrates

Lipids

Proteins

DNA, ATP

Proteins

Functional Groups

Functional Groups in Action

Carbon

• Significant basis of all living organisms • Creates a large diversity of biological molecules

– 4 main classes*• Carbohydrates• Lipids• Proteins• Nucleic Acids

– Distinguishes living from nonliving matter• All these molecules are examples of emergent properties

* important to know the monomers, polymers, and examples

Building Organic Molecules• Monomers are universal or similar units in all forms

of life• Polymers are functional components of cells

– DNA is composed of 4 types of nucleotides• Variation based on arrangement

– Proteins are composed of 20 different amino acids (AA’s)• Variation distinguishes within and between species

Making and Breaking MacromoleculesDehydration reaction

• Links monomers• Loss of water for each

monomer added• Forms a covalent bond

Hydrolysis reaction

• Breaks polymers• Addition of water for

each broken bond

1 42

21

3

3 4

1

2

2 3

3

4

41

Carbohydrates

• Range from sugar in beverages to starch in foods• Basic composition

– CH2O (1:2:1 ratio) – Have hydroxyl and carbonyl group– End in ‘-ose’– Hydrophilic (means what?; why?)

• Types– Monosaccharides – Disaccharides – Polysaccharides

• Energy storage

Monosaccharides

• Simple sugars (monomers)– Glucose and fructose

• Isomers (means what?)• Fructose is sweeter

– Galactose• Main fuel for cells

– Unused get incorporated into more complex sugars

• Most 3-7 carbon atoms long

Disaccharides

• 2 monosaccharides joined by a glycosidic bond– Dehydration reaction

• Maltose– glucose + glucose– Whoppers©, malts, beer

• Sucrose– Glucose + fructose– Table sugar– Plant sap

• Lactose– galactose + glucose

Polysaccharides

• Insoluble fiber• Storage

– Glycogen in animals (short term)– Starch in plants

• Structure– Cellulose in plant cell walls

• Not always digestable

– Chitin in insect and crustacean exoskeletons• Protection and nutrients for animals• Surgical thread

Lipids• Not true polymers• Long term energy storage• Insoluble

– Salad dressing (o & v)– Bird feathers (repellent beads)

• 3 types– Triglycerides (fats)

• Saturated are solid at room temp– Animal fats

• Unsaturated are liquids at room temp– Plant fats (oils)

– Phospholipids– Steroids

• Sex hormones• Synthetic forms

Proteins

• Polypeptide chain with a specific shape– Polymer of 20 amino acids (AA’s)– Variation determines structure and function

• Multiple roles– Enzymes: speed chemical reactions, end in ‘-ase’– Structural: hair and connective tissue– Signal: hormones for communication

• Altered by denaturation– Changes in [salt], pH, or excessive heat– Danger of high fevers

Amino Acids

• Common structure varied by side chain (R)• Properties determined by R group

– Hydrophilic or hydrophobic– (+) or (-) charge

• Dehydration reaction joins AA’s– Forms peptide bonds– Dipeptide = 2 AA’s joined– Polypeptide = multiple AA’s

• Hydrolysis reverses– Eating meat

• All polypeptides are not proteins

Protein Structure• Primary (1°)

– Sequence of AA’s determined by DNA

• Secondary (2°)– Folds (β-pleated sheet) and coils

(α-helix) from H-bonding• Tertiaty (3°)

– 3D shape of polypeptide– Globular or fibrous

• Quartenary (4°)– 2+ associated polypeptide chains

• Single change can change shape which changes function

Nucleic AcidsDNA

• Genetic code• Nucleotides

– Deoxyribose sugar– Phosphate group– 4 nitrogenous bases

• Adenine (A)• Cytosine (C)• Guanine (G)• Thymine (T)

• Double stranded– Hydrogen bonds w/i

• A & T• C & G

RNA

• Protein synthesis• Nucleotides

– Ribose sugar– Phosphate group– 4 nitrogenous bases

• Adenine (A)• Cytosine (C)• Guanine (G)• Uracil (U)

• Single stranded– Hydrogen bonds similar

• A & U• C & G

Basis For Life and Individuality

• Primary structure of polypeptides is determined by genes, discrete units of inheritance

• Genes are sequences of DNA– DNA determined by organization of 4 nucleotides

• DNA RNA proteins (polypeptides)

– Central dogma of molecular biology• Genes are the blueprint for the living organism

seen

transcribed

translated

Review of Biological Macromolecules

Macromolecule• Carbohydrates• Proteins• Nucleic acids• Lipids*

Monomer/Polymer(s)/E.g.• monosaccharide/ ?/ ?• ?/ polypeptide/ ?• ?/ nucleic acids/ ?• glycerol and FA’s/ ?/ ?*

* Not true monomer/polymer match