BIOCHEMISTRY

CHAPTER 2

SECTION 2-1: 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 H2O

SECTION 2-2: 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

SECTION 2-3: CARBON COMPOUNDS

• Organic compounds- those compounds that contain carbon

• Chemical Formulas - show how many and which atoms are in a compound

• Structural Formulas - show the arrangement of the atoms in a compound

• Isomers - compounds with the same chemical formula, but different structure (ex. propanol and isopropanol)

COVALENT BOND #’S

•Atoms want to fill their electron shells. An atom wants to make just enough bonds to fill its shells.

•H makes one bond•O makes two bonds•C makes four bonds

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

All of these food contain

carbohydrates.

Which foods contain the

most calories from Carbs?

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 C6H12O6, but

they are isomers• Draw Glucose

DISACCHARIDES

• Double sugars (two monosaccharides combined)

• Examples: sucrose, lactose, and maltose

• All are isomers with the chemical formula C12H22O11

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.

98% Calories from Carbs

94% Calories from Carbs

64% Calories from Carbs

55% Calories from Carbs

DEHYDRATION SYNTHESIS

• Two molecules join together by losing a molecule of water

HYDROLYSIS REACTION

• Larger molecules broken down into smaller molecules by the addition of water

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, C57H110O6

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

Alanine Serine

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

SECTION 2-4: 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 pathwaywith enzyme

Reaction pathwaywithout enzyme

Activation energywithout enzyme

Activation energywith 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.