BIOCHEMISTRY

THE NATURE OF MATTER REMEMBER… Atoms are made up of electrons (-), neutrons (neutral), and protons (+) Proton number = atomic number = type of element

Bonds Ionic bond – when electrons are transferred from one atom to another –Example NaCl Covalent bond – electrons are shared between atoms –Example H 2 O

PROPERTIES OF WATER Polarity – uneven distribution of electrons between the hydrogen and oxygen atoms –Oxygen is bigger and attracts the electrons more than hydrogen Hydrogen bonds – slightly positive, polar H atoms are attracted to polar negative atoms like O

Acids and Bases Acids –Compounds that form hydrogen ions ( H+) when dissolved in water –Ex. Lemon juice Bases –Compounds that reduce the amount of hydrogen ions in a solution. Usually bases form hydroxide ions (OH -) instead of hydrogen ions when dissolved in water. –Ex. Ammonia

MACROMOLECULES Monomers (smaller units) join to make polymers or macromolecules –Carbohydrates –Lipids –Proteins –Nucleic acids

CARBOHYDRATES Organic compounds composed of carbon, hydrogen and oxygen with a ratio of two hydrogen atoms to every one oxygen atom Made up of sugars

USE OF CARBOHYDRATES Source of energy for many living things Examples: sugar and starch

TYPES OF CARBOHYDRATES Monosaccharides Disaccharides Polysaccharides

MONOSACCHARIDES Only one sugar molecule Examples -glucose, fructose, and galactose All three are C 6 H 12 O 6, but they are isomers Draw Glucose

DISACCHARIDES Double sugars (two monosaccharides combined) Examples: sucrose, lactose, and maltose All are isomers with the chemical formula C 12 H 22 O 11

POLYSACCHARIDES Long chains of monosaccharides joined together Examples: starch, glycogen, and cellulose Plants store excess sugar as starch, and break it down for energy

Humans store excess sugar as glycogen, & break it down for energy Cellulose used by plants to build cell walls.

Carbohydrates and Nutrition Beware of low carbohydrate diets –Low carbohydrates cause your body to break down muscle (protein) –Low carbohydrates can cause your appetite to increase (your body thinks it is starving) Eat whole grains! –Whole grains provide fiber and help to prevent heart disease and cancer.

DEHYDRATION SYNTHESIS Two molecules join together by losing a molecule of water DRAW

HYDROLYSIS REACTION Larger molecules broken down into smaller molecules by the addition of water Draw

LIPIDS Include fats, oils, steroids & waxes Composed of carbon, hydrogen and oxygen, but the # of H atoms per molecule is much greater then the # of O atoms An example, C 57 H 110 O 6

USES OF LIPIDS Stored for energy Form basic structure of cell membranes Protection Insulation Waterproof coverings

THE STRUCTURE OF SOME FATS Fatty Acids (a common type of fat): –a long carbon chain with a -COOH (carboxyl group) at one end

Different types of fatty acids: –Saturated - all single, covalent bonds in between carbons in chain –Unsaturated - one double bond between carbons in chain –Polyunsaturated - many double bonds between carbons in chain

Steroids include: –Cholesterol -made by animals and is both helpful & harmful –Testosterone/Estrogen – male/female hormones –Cortisone – medicine used to reduce swelling/itching

Fats and Nutrition Unsaturated fat is better for you than saturated fat. Double bonds are easier to break than single bonds. High fat diet actually increases appetite. To increase fat break down, you must increase physical activity. Good fats are found in some fish, olives, and nuts and actually help to prevent heart disease.

PROTEIN Made up of amino acids linked together Composed of C, H, & O as well as nitrogen, N, and possibly sulfur

USES OF PROTEINS Build living materials like muscle Act as enzymes to help carry out chemical reactions Fight disease Transport particles into or out of cells Act as markers on cells

AMINO ACID STRUCTURE Have a central C that is bound to: –carboxyl group (-COOH) –a hydrogen atom –a amino group (-NH2) –an “R” group (Draw)

AlanineSerine General structure

There are 20 main amino acids. Each has same basic structure with the only difference being the “R” group Amino acids are linked by peptide bonds (formed by dehydration synthesis)

Peptide bond is between two amino acids Polypeptide – (a protein) many amino acids joined

Protein and Nutrition Proteins help to suppress appetite so eat a little at every meal. Proteins help build lean body mass. Increased lean body mass increase your BMR (basal metabolic rate). –This means that you burn more calories. Yo-yo dieting decreases BMR and makes your body store fat.

NUCLEIC ACIDS Composed of nucleotides Nucleotides consist of a sugar, a nitrogenous base, and a phosphate Nucleic acids include: DNA, RNA, ATP, and NAD

Figure 16.5 The double helix

CHEMICAL REACTIONS Chemical reactions always involve breaking bonds in reactants and making bonds in products Some reactions release energy and therefore usually occur spontaneously Other reactions need energy to happen

Activation energy – the minimum amount of energy needed to start any reaction Enzymes are catalysts which speed up chemical reactions Enzymes are proteins that lower activation energy and allow reactions to occur at normal temperatures Without enzymes, too much energy would be needed to start all of the thousands of reactions your body performs all of the time!

Reaction pathway with enzyme Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme

Each enzyme is specific and has a specific shape Enzymes are not permanently changed and are not used up in the reaction

Most enzyme names end in -ase Reactants are called substrates. Enzymes work on substrates (either breaking them down or adding something to them. Example: Lactase (enzyme) breaks down lactose (substrate), which is the sugar in milk.

Factors that affect enzyme activity Enzymes are made of protein and there are certain factors that affect protein shape If the proteins shape is altered it will no longer work Factors –pH –Temperature –Salt concentration