Biochemistry The Molecules of Life

Chemistry in Living Systems Elements: simplest form of a substance - cannot be broken down any further without changing what it isElements: simplest form of a substance - cannot be broken down any further without changing what it is Atom: the actual basic unit - composed of protons, neutrons, and electronsAtom: the actual basic unit - composed of protons, neutrons, and electrons

The Atom Just like cells are the basic unit of life, the ATOM is the basic unit of matter.Just like cells are the basic unit of life, the ATOM is the basic unit of matter. They are very small. If placed side by side one million would stretch a distance of 1cm.They are very small. If placed side by side one million would stretch a distance of 1cm. The atom is made up of 3 particles.The atom is made up of 3 particles. ParticleCharge PROTON PROTON+ NEUTRONNEUTRAL ELECTRON-

Electrons are not present within the atom, instead THEY REVOLVE AROUND THE NUCELUS OF THE ATOM & FORM THE ELECTRON CLOUDElectrons are not present within the atom, instead THEY REVOLVE AROUND THE NUCELUS OF THE ATOM & FORM THE ELECTRON CLOUD Draw a helium atom. Indicate where the protons, neutrons and electrons are.Draw a helium atom. Indicate where the protons, neutrons and electrons are PROTONS NEUTRONS ELECTRONS ATOMIC # = 2 (PROTONS) ATOMIC MASS = 4 (PROTONS & NEUTRONS)

ISOTOPES atoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONSatoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONS Some isotopes are radioactive. This means that their nuclei is unstable and will break down at a CONSTANT RATE over time.Some isotopes are radioactive. This means that their nuclei is unstable and will break down at a CONSTANT RATE over time. There are several practical uses for radioactive isotopes:There are several practical uses for radioactive isotopes: 1.CARBON DATING 2.TRACERS 3.KILL BACTERIA / CANCER CELLS

Common Elements The cell is a COMPLEX CHEMICAL FACTORY containing some of the same elements found in the nonliving environment.The cell is a COMPLEX CHEMICAL FACTORY containing some of the same elements found in the nonliving environment. carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) are present in the greatest percentages in living systemscarbon (C), hydrogen (H), oxygen (O), and nitrogen (N) are present in the greatest percentages in living systems Most atoms are found in living systems as molecules (2 or more non-metal atoms bonded together).Most atoms are found in living systems as molecules (2 or more non-metal atoms bonded together).

TWO TYPES OF COMPOUNDS Organic - Contain C, H, and O in some ratio (usually referred to as chemicals of life)Organic - Contain C, H, and O in some ratio (usually referred to as chemicals of life) –Carbohydrates, Proteins, Lipids, Nucleic Acids Inorganic - usually "support" life - no specific ratio of C, H, and OInorganic - usually "support" life - no specific ratio of C, H, and O –Water (H2O), Carbon Dioxide (CO2)

Interactions Within Molecules Intramolecular forces: chemical bonds within a molecule –Covalent bonds: 2 non-metal atoms share electrons equally –Polar Covalent bonds: when one atom attracts electrons more than the other, it creates a partial negative charge

Interactions Between Molecules Intermolecular forces: forces of attraction between molecules –Hydrogen Bonding: a weak bond between an atom with a partial negative and a hydrogen atom with a partial positive charge. –Hydrophobic Interactions: when non-polar molecules group together to stay away from the polar molecules.

Functional Groups An atom or group of atoms attached to a molecules that gives the molecules particular chemical and physical properties.

Macromolecules Molecules that are large and complex Often made up of repeating subunits called monomers. Carbohydrates: contain carbon, hydrogen, oxygen in a 1:2:1 ratio –Monosaccharides : one sugar (glucose, fructose, galactose. Fun Bio Challenge: You must be able to draw these !

–Disaccharides: two monosaccharides join together forming a glycosidic linkage. –Polysaccharides: many monosaccharides join together. Starch: alpha glycosidic linkage between monomers. Stored energy found in plants Glycogen: alpha glycosidic linkage between monomers. Stored energy found in animals Cellulose: beta glycosidic linkage between monomers. Provides structural support in plant cell walls.

Lipids: made of C, H and O atoms, but have fewer oxygen atoms and are mainly hydrophobic –Provides longer-term energy for animals –Triglycerides: made of one glycerol and 3 fatty acids joined by an ester linkage Saturated fatty acids: no double or triple bonds Unsaturated fatty acids: one double or triple bond Polyunsaturated fatty acids: more than one double or triple bond. –Phospholipids: a lipid made of a glycerol bonded to two fatty acids and an “R” group “Head” is hydrophilic, “tail” is hydrophobic

–Steroids: lipids that have four carbon based rings attached to each other Cholesterol Estrogen Testosterone –Waxes: long carbon-based chains that are solid at room temperature.

Macromolecules Continued… Proteins contain the elements carbon, hydrogen, oxygen, and nitrogencontain the elements carbon, hydrogen, oxygen, and nitrogen composed of MANY amino acid subunitscomposed of MANY amino acid subunits It is the sequence of the amino acid that forms the primary structure of proteins.It is the sequence of the amino acid that forms the primary structure of proteins. The basic amino acid form has a carboxyl group on one end, a methyl group that only has one hydrogen in the middle, and a amino group on the other end.The basic amino acid form has a carboxyl group on one end, a methyl group that only has one hydrogen in the middle, and a amino group on the other end. Attached to the methyl group is a R group.Attached to the methyl group is a R group.

Uses for Proteins: –As enzymes that catalyze chemical reactions in the body –Structural support in bones, tendons, skin, hair, nails –Transporting chemicals in the body –Locomotion for animals: muscle contraction –Hormones –antibodies

There are 20 common amino acids with 8 of them being essential amino acids that cannot be made in the body and must be consumed.

Protein Structure Primary Structure: the sequence of amino acids connected together through peptide bonds Secondary Structure: coil-like alpha helix shapes and folded beta sheets due to hydrogen bonds Tertiary Structure: 3D shapes of proteins Quaternary Structure: multiple polypeptide chains arranged together

Macromolecules continued… Nucleic Acids Two types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) Contain genetic information Made up repeating nucleotide monomers. Each monomer contains: –A phosphate group –A sugar with five carbons (deoxyribose or ribose) –A nitrogenous base (Adenine, thymine, guanine, cytosine in DNA and in RNA the same but thymine is replaced by uracil)

A polymer of nucleotides is a strand that joins adjacent nucleotides with a phosphodiester bond (between the phosphate and the hydroxyl groups) DNA is two strands twisted in a double helix The two strands are held together by hydrogen bonds Thymine always bonds with adenine (with 2 H-bonds) and cytosine always bonds with guanine (with 3 H- bonds). These are called complementary base pairs.