College Bio Chpt. 3 &4

Carbon Atom

*has 6 electrons

*can form diverse molecules by bonding four other atoms

*acts as an intersection point from which a molecule can branch off in as many as 4 directions

*bond is covalent

How does valence work?

valence describes the combining power of an atom, measured by the # of chemical bonds it can form

Molecular Diversity

Ethan, propane, 1-Butene, 2-Butene, Butane, 2-Methylpropane, Cyclohexane, Benzene.

*these compounds only contain a connection of C and H. they are HYDROCARBONS (organic molecules consisting of only carbon and hydrogen)

*shapes are different

Isomers

structures that have the same number of atoms of the same elements, but different structures and therefore different properties

*3 types: structural isomers, cis-trans isomers, and enantiomers

Important Biological Chem Groups

Macromolecules are Polymers built from Monomers

-macromolecules form when small building blocks (monomers) link together through dehydration synthesis (condensation) *cells join monomers with covalent bonds and release water as byproduct

-macromolecules are broken down through hydrolysis *a water molecule is added across the covalent bond holding the polymer together, which splits the bond, releases energy, and turns large chains into usable, bite-sized nutrient parts

Synthesis & Breakdown of Polymers

synthesis: polymers are created via the dehydration reaction

*monomers are connected covalently by the LOSS of a water molecule. Each monomer contributes part of the water molecule

• OH = hydroxyl group

• H = hydrogen

*breakdown of polymers: polymers are disassembled into monomers via hydrolysis (water breakage)

*covalent bond between monomers is broken by the addition of a water molecule

• H attaches to one monomer

• OH attaches to another

4 Main Macromolecules

*all macromolecules are polymers

A. carbohydrates

B. Lipids

C. Proteins

D. Nucleic Acids

A. Carbohydrates

*Includes sugars (saccharides)

*monomer = monosaccharides

*polymer = (disaccharides) and polysaccharides

Monosaccharides

Glucose: C6H12O6

Function: serve as raw materials for creation of other molecules and extraction of energy (quick energy)

Trademarks: carbonyl groups C=O and multiple hydroxyl gps *-OH

Most stable form is in a ring

Glucose structure vs. structure (both monosaccharides)

Disaccharides & Glycosidic Linkage

disaccharides: 2 monosaccharides joined together

glycosidic linkage: bond between 2 monosaccharides that creates a covalent bond via dehydration reaction

*most popular = sucrose (table sugar)

• glucose + fructose = sucrose

• Beer: lactose, Milk: lactose

- Glycosidic Linkage bond holds monomers together in Carbohydrates

Polysaccharides

- polysaccharides: macromolecule (polymer) of sugar

*100’s to 1000’s of monomers brought together via glycosidic linkage

2 main types:

a. storage polysaccharides

b. structural polysaccharides

Storage polysaccharides

- storage sugar for later use

Plants: store STARCH (glucose chain)

Animals: store GLYCOGEN in liver and muscles; depleted much faster in humans (within a day)

Structural Polysaccharides

2 main types:

a. CELLULOSE: major component of plant walls that enclose the cell; gives a 3-D shape

*many enzymes cannot break this down

**humans: important part of the fiber in our diets

Chitin

carb polysaccharide used by arthropods (insects, spiders, crustaceans) to build their exoskeletons; also found in fungi to build their cell walls

B. Lipids

*long-term energy

• includes fats, phospholipids, and steroids

• bonds in lipids: ester linkage holds the head and tails together

Fats

- made up of a glycerol & a fatty acid

• glycerol: C with a hydroxyl group

• Fatty acid: 16-18 C atoms in length with a H attached (hydrocarbon chains)

Typically, there are 3 chains called a triacylglycerol (3 fatty acids to one glycerol)

2 Types of Fatty Acids

1. saturated: no double bonds between C; “hard fats”

2. unsaturated: one or more double bonds between C creating a kink; “liquid fats”

Phospholipids

- make up the cell membrane in a bilayer

*similar to a “fat molecule” because it has two fatty acids attached to a glycerol rather than 3

Head: hydrophyllic

Tail: hydrophobic

Steroids

- 4 fused C rings

Found in an animal cell membranes

Cholesterol: crucial steroid in animals; also makes up estrogen and testosterone

*synthesized in liver but also consumed by animals

C. Proteins

Instrumental in most everything and organism does; chemical reactions, defense, storage, cell communication, transport, support, etc.

Enzymes: proteins that act as CATALYSTS (speed up chemical reactions)

*10,000+ polymers made from 20 amino acids (monomers)

**biologically functional molecule made up of 1 or more polypeptides folded and coiled into 3-D structures

Polypeptide

*each has a unique linear sentence of amino acids (allows for creation of thousands of different amino acids)

N - terminus: free amino group

C - terminus: carboxyl end

Protein Structure & Function

*determined by its 3-D shape

There are 4 levels of protein structure:

Primary

Secondary

Teriary

Quaternary