BIO 100 Chapter 3

Carbon Atom

Total of 6 electrons — four in outer shell

almost always shares electrons with elements such as hydrogen, nitrogen, and oxygen

Can bond with as many a 4 other elements

Functional Group

Specific combination of bonded atoms that always has the same chemical properties and always reacts the same way.

Common Functional Groups

• Hydroxyl

• Carboxyl

• Amine

• Sulfhydryl

• Phosphate

Monomers

Subunits

Polymer

monomers joined together

Dehydration synthesis reaction

joins monomers to form polymers, equivalent of removing a water moleculeH

Hydrolysis Reaction

OH group attaches to one monomer and H from water attaches to the other monomer; used to break bonds in a polymer

Biological Molecules

• Carbs

• Lipids

• Proteins

  • Nucleic Acids

Carohydrates

mainly used for immediate energy

May also be used for structural components

Carbs are classified as

• monosaccharides

• disaccharides

  • polysaccharides

Monosaccharides

Simple sugar molecule

simple sugars

three to seven carbon backbone

Disaccharides

Two monosaccharides bonded together

Maltose

yeast breaks down maltose in beer for energy and produces ethyl alcohol

Sucrose

table sugar

Polysaccahrides

used as energy storage molecules

polymers of monosaccharides

can function as energy storage or structual components

Cellulose

plant cell walls

Chitin

crab, lobster, insect exoskeletons

Lipids

insoluble in water

long non polar hydrocarbon chains

Phospholipids

form the bulk of plasma membrane

one end of the molecule is water-soluable

polar phosphate head, non polar fatty acid tails

Steriods

Lipids made of four fused rings

no fatty acids but are insoluble in water

derived from cholesterol

Proteins

Functions: support, metabolism, transport, defense, regulation and motion

composed of amino acid monomers

Peptides

two or more amino acid covalenty linkedP

Peptide Bond

formed by dehydration reaction between amino acid monomersP

Polypeptide

chain of many amino acids joined by peptide bonds

Function determined by 3D shape

Shape of proteins

Secondary structure of proteins

portions of chain form helices or pleated sheets

Tertiary structure

overall 3d shape of interacting secondary structures

Quaternary structure

more than on polypeptide chain interacting

Deoxyribonucleic Acid (DNA)

Stores genetic information

Ribonucleic Acid (RNA)

Helps to make proteins

DNA

deoxyribose as sugar

double helix

RNA

ribose as sugar

single stranded