Ch 2- The chemistry of life

chemical element

Simplest matter with unique chemical properties.

What does atomic number represent?

Number of protons.

O, C, H, N, Ca, P.

Six most abundant elements in the body?

atom

Whats the smallest unit of matter?

minerals

Inorganic elements from soil; support structure, enzymes, nerves, muscles.

Protons and neutrons.

What particles are in the nucleus?

+1 charge, 1 amu.

Charge and mass of a proton?

No charge, 1 amu.

Charge and mass of a neutron?

–1 charge.

Charge of an electron?

valence electrons

Electrons in the outer shell that determine bonding.

isotopes

varieties of an element that differ only in the number of neutrons and therefor in atomic mass

Radioisotopes

Unstable isotopes that decay and emit radiation.

Creates free radicals, damages DNA, causes cancer.

Ionizing radiation dangers?

• Physical: time for 50% to decay.

• Biological: time for 50% to leave body.

Physical vs biological half-life?

Sievert (Sv).

Unit of radiation dose?

ion

Charged atom or molecule with unequal number of protons and electrons

anion

particle that has a net negative charge due to gain of electrons

cation

particle that has a net positive charge due to loss of electrons

electrolyte

Substance that ionizes in water and conducts electricity.

Chemical reactivity, osmotic balance, nerve/muscle activity.

Electrolyte functions?

free radicals

unstable highly reactive particles with odd electrons.

antioxidants

Molecules that neutralize free radicals.

• Molecule: 2+ atoms

• Compound: 2+ different elements

Molecule vs compound?

isomers

Same formula, different structure.

ionic bond

Attraction between anion and cation.

Covalent bond

Atoms share electrons.

• Nonpolar: equal sharing.

• Polar: unequal sharing.

Nonpolar vs polar covalent?

hydrogen bond

Weak attraction between H+ and O/N.

van der Waals forces

Weak, brief attractions due to electron fluctuations.

Polar and forms hydration spheres.

Why is water a good solvent?

cohesion

Water molecules stick to each other.

adhesion

Water sticks to other surfaces.

Ionizes and participates in hydrolysis/dehydration.

Chemical reactivity of water?

High heat capacity.

What gives water thermal stability?

solution

Solute <1 nm, clear, passes membranes, doesn’t settle.

colloid

1–100 nm particles, cloudy, no settling.

suspension

>100 nm, cloudy, settles.

emulsion

One liquid suspended in another.

• Acid donates H+.

• Base accepts H+.

Acid vs base?

buffer

Prevents pH changes.

Molarity

Moles per liter.

• Potential is stored energy

• kinetic is energy in motion

Potential vs kinetic energy?

AB → A + B.

Decomposition reaction?

A + B → AB.

Synthesis reaction?

AB + CD → AC + BD.

Exchange reaction?

Catabolism

Breaks molecules → releases energy.

Anabolism

Builds molecules → requires energy.

Oxidation

Loss of electrons.

Reduction

Gain of electrons.

Redox reactions

Coupled oxidation and reduction.

carbon versatile

4 valence electrons → forms many structures.

Hydroxyl, methyl, carboxyl, amino, phosphate.

Examples of functional groups?

polymer

Long chain of monomers.

Dehydration synthesis

Removes H2O to join monomers.

Hydrolysis

Adds H2O to split monomers.

(CH2O)n.

General formula for carbs?

• Glucose

• galactose

• fructose.

Three main monosaccharides?

• Sucrose

• lactose

• maltose

Three main disaccharides?

RNA sugar vs DNA sugar.

Ribose vs deoxyribose?

eicosanoids

• 20-carbon lipids derived from arachidonic acid.

• Act as hormone-like signals between cells.

Inflammation, blood clotting, hormone action, labor contractions, vessel diameter.

Functions of prostaglandins?

steroid

Lipid with 17 carbon atoms in four rings.

Cholesterol.

Parent steroid?

Needed for nervous system function and all cell membranes.

Why is cholesterol important?

15% diet, 85% made in liver.

Where does cholesterol come from?

HDL

High-density lipoprotein; “good”; lower lipid:protein ratio; protective.

LDL

Low-density lipoprotein; “bad”; high lipid:protein ratio; increases CVD risk.

protein

Polymer of amino acids.

Central carbon + amino group + carboxyl group + R group.

Amino acid structure?

R group.

What determines amino acid properties?

peptide bond

Bond between amino group of one AA and carboxyl group of the next; formed by dehydration synthesis

AA sequence (gene-encoded).

Primary structure?

Alpha helix or beta sheet, formed by hydrogen bonds.

Secondary structure?

Further folding from hydrophobic interactions, van der Waals forces, disulfide bridges.

Tertiary structure?

enzymes

Protein catalysts.

cofactor

Nonprotein partner needed by some enzymes.

coenzymes

Organic cofactors from vitamins.

metabolic pathway

Chain of reactions, each with its own enzyme.

nucleotide

Nitrogen base + sugar + phosphate(s).

ATP

• Main energy-transfer molecule.

• Adenine + ribose + 3 phosphates.

Phosphorylation

Adding a phosphate to another molecule; done by kinases.

DNA

Millions of nucleotides; genes for proteins.

RNA

Carries instructions and assembles proteins.