AP Bio Unit 1

Water

-polar molecule

-oxygen is more electronegative than hydrogen

-hydrogen bonds

Hydrogen bonds

Individually weak but collectively strong

-constantly break and reform

Cohesion

Water molecules stick to each other

Adhesion

Water molecules stick to other polar/charged surfaces

Surface tension

Cohesion at the surface creates a “film”

Capillary action

Cohesion + adhesion pull water through narrow spaces

Solvent properties

Polar water dissolves polar and charged (hydrophilic) substances

Carbon

-backbone of biological molecules because it forms up to 4 covalent bonds

Nitrogen

Proteins (amino groups), and nucleic acids (nitrogenous bases)

Phosphorus

Nucleic acids (phosphate groups), phospholipids, ATP

Sulfur

Some amino acids

-helps form disulfide bridges in proteins

Polymers

-large biological molecules

-built from repeating subunits (monomers)

-requires energy input to build

Dehydration synthesis

-(condensation)

-Monomers are covalently joined

-removes water

-builds polymers

-Requires energy

-catalyzed by enzymes in cells

Hydrolysis

A water molecule is added to break the covalent bond between monomers

-releases subunits and energy

-catalyzed by enzymes in cells

-breaks polymers

Monomer

Amino acid (a central carbon bonded to an amino group, a carboxyl group, a hydrogen, and a variable R group)

Monosaccharide

Typically a 121 ratio of CHO

Nucleotide=phosphate group + 5carbon sugar+ nitrogenous base

Ex. Glucose, amino acids, and nucleotides

Monosaccharides

A type of monomer

Join by glycosidic linkages to form disaccharides and polysaccharides

Starch/plants and glycogen/animals

Storage

Cellulose/plants and chitin/fungi + arthropods

Structure

Lipids

-long term energy, membranes, hormones, insulation

-non polar and hydrophobic

-their many C-H bonds make fats an efficient, compact energy store

-fatty acids

-triglycerides

-Phospholipids

-steroids

Ester linkage

Saturated fatty acids

No carbon carbon double bonds

Straight chains pack tight

Solid at room temp

Unsaturated fatty acids

One or more carbon carbon bonds create kinks in the chain

Molecules cannot pac tightly

Liquid at room temp

Triglycerides

Glycerol and 3 fatty acids

Joined by dehydration synthesis

Long term energy storage

Phospholipids

Glycerol and 2 fatty acids and a phosphate group

Amphipathic (hydrophilic polar phosphate head and hydrophobic nonpolar fatty acid tails)

In water they self-assemble into bilayers (the foundation of all cell membranes)

Steroids

4 fused carbon rings

Ex cholesterol which moderates membrane fluidity

Kink logic

Double bonds-kinks-looser packing-more fluid/liquid

DNA

Stores genetic info

Deoxyribose

Bases:A,T,G,C

Double stranded anti-parallel helix

Held by hydrogen bonds

A-T:2 hydrogen bonds

G-C:3 hydrogen bonds

RNA

Helps synthesize protein’s from DNA’s instructions

Ribose

Bases:A,U,G,C

Usually single-stranded

Carbohydrates

Monosaccharides

Glycosidic linkage

Quick energy, energy storage, structure

Nucleic acids

Store and transmit genetic info

Nucleotide

Phosphodiester (sugar-phosphate backbone) is the bond joining unit

Protein

Enzymes, structure, transport, signaling, defense

Amino acid Joined by Peptide bonds

Ex hemoglobin, enzyme

4 levels of protein structure

Primary: linear sequence of amino acids

Secondary:Beta pleated sheet or helix, stabilized by hydrogen bonds between backbone atoms

Tertiary:globular or disulfide bridges, driven by R group interactions

Quaternary: 2 or more polypeptides

Denaturation

Heat, ph changes, or chemicals disrupt the interactions that hold the shape, so the protein unfolds and loses function