Ch. 2: The Chemical Basis of Life

Anatomy

Matter

anything that takes up space and has mass (all matter is composed of elements)

Reductionist approach

Scientific approach based on the idea that the whole can best be understood by studying its parts

What four elements make up the bulk of living matter?

Carbon, Hydrogen, Oxygen, Nitrogen

Atoms

smallest particle of matter with the properties of an element (elements contain atoms)

contain protons, neutrons, and electrons

Always start with neutral charge (containing the same amount of protons and electrons)

Proton

in the atomic nucleus, contains a positive charge, 1 amu (atomic mass unit)

Neutron

in the atomic nucleus, neutral (no charge)

Electron

in the electron shells, negative charge

Subatomic particles

Atom is made up of protons and neutrons that are located in the central nucleus

the nucleus is surrounded by electrons in the electron shells

Atomic number

number of protons

Atomic mass

protons + neutrons

average mass of naturally occurring isotopes

Isotopes

atoms of an element with different numbers of neutrons (same number of protons and electrons)

Radioactive isotopes

nucleus decays, giving off particles and energy = radiation (unstable)

Ionic Bond

Attraction between oppositely charged ions

Ion

Atom or molecule that has lost or gained electrons

Cation

Loss of electrons making a positive charge

Anion

Gaining electrons making a negative charge

Covalent Bond

when atoms share electrons in their outer shell to get a full outer shell

Nonpolar

when the electrons are shared equally (ex: H2O2)

Polar

when the electrons are shared unequally (ex: H2O)

Molecule

2 or more atoms held together by covalent bonds

Hydrogen Bond

the attraction between oppositely charged ends of a polar molecule creating a weak bond (ex: water molecules)

Hydrogen is always at the positively charged end of a polar molecule

Organic molecules

Molecules made by cells and contain C and H

Monomer

building blocks of organic macromolecules (ex: amino acids, monosaccharides)

Polymer

Macromolecule made by linking many monomers together (ex: proteins, polysaccharides)

Dehydration synthesis

Combines monomers by removing a water molecule between monomers

Hydrolysis

breaks monomers apart by inserting a water molecule between them

Carbohydrates

• made from Carbon and water. (ratio: 1 C for every water molec.)

• Monosaccharides (monomers) made of 3-7 Carbon backbone (Ex: glucose, galactose)

• Polysaccharides (polymer) made by linking monosaccharides together by dehydration synthesis

Disaccharides

• Cells link two single sugars to form these

  • Monosaccharides such as sucrose (table sugar) and maltose (brewing sugar) can join to form these

Examples of Polysaccharides and their purpose

Starch and glycogen - store sugar for later use

Cellulose - polysaccharide found in plant cell walls that stores sugar for later use

Proteins

• Amino acids = monomers

• Polypeptides = polymers (long chain of amino acids)

• Proteins can be made of one or more polypeptides

How are amino acids linked together?

By dehydration synthesis; the bonds between amino acid monomers are called peptide bonds

Lipids

• Fatty acids and glycerol = monomers

• Fats, oils, and waxes = polymers

Another name for fats & their funcitonq

Triglycerides (consists of glycerol linked to 3 fatty acids); main function is energy storage

Saturated Fats

contains all single bonds in the carbon chain, which produces a more rigid structure

Unsaturated fats

• contains one (mono) or more (poly) double bonds in the carbon chain, which produces a more relaxed structure

  • better because they do not stick to the inside of blood vesselsT

Trans fat

• unsaturated fats that are artificially altered to be more saturated

• Are the highest CV risk fat

• Ex: Margarine (made up of vegetable oil, which is typically liquid at room temperature, but altered to be a solid)

Nucleic Acids

• Nucleotides (made of sugar, phosphate, nitrogenous base) = monomers

• Nucleic acids = polymers (ex: DNA, RNA)

DNA consists of

Two polynucleotides which twist around each other in a double helix