Biochemistry

Biochemistry

• Study of chemical reactions that take place in our body everyday

• Chemical reactions allow us to remain alive– Rearrangement of chemical bonds to form products

from reactants

Macromolecules

Water • Most abundant molecule in any cell • Acts as a carrier for dissolved molecules across

cell membrane• Used in chemical reactions– Cellular respiration, photosynthesis

• Lubricant between organs, tissues, and cells

What Makes Water so Important?• Remains liquid over wide range

of temps• Dissolves most substances

important for cellular function– Oxygen, carbon dioxide, glucose,

amino acids• Gradual change in temperature

when heated or cooled – helps maintain homeostasis

• Expands when it becomes solid • Polar – uneven charge

What Makes Water so Important?

Water • Dipole nature– Two charges that belong to a water molecule– Small positive charge on two hydrogen atoms– Small negative charge on oxygen atom

What do you notice about this picture?

Macromolecules

• Organic compounds– Contain both hydrogen and carbon

• Large molecules composed of smaller subunits– Carbohydrates– Proteins– Lipids– Nucleic Acids

Carbohydrates (Sugars)• Biomolecule consisting of

carbon, oxygen, and hydrogen.

• General molecular formula (CnH₂nOn) (C₆H₁₂O₆)

• Roles– Energy storage - plants – Structural support in cells and

tissues • Hydrophilic • Pentose/Hexose ring structure

Monosaccharides• Used as primary energy

source for cellular metabolism (making ATP)

• 1 sugar unit – Glucose – grape sugar,

blood sugar– Fructose – honey, fruit

juices

Disaccharides• Consist of two monosaccharides – Maltose – used to make beer – Sucrose – simple sugar found in plant sap– Lactose – milk

• Used as energy sources and building blocks for larger molecules

Polysaccharides• Complex carbohydrate/polymer– Chain of hundreds to thousands of monosaccharides

(monomers) with many subunits– Unbranched – side chains – Branched – single chain

Examples

Amylose – soluble component of starch

Glycogen – energy storage in animals

Cellulose – main component of plant cell walls

Chitin – hard exoskeleton of insect and crustaceans

Lipids• Non-polar • Made up of mostly

carbon and hydrogen • Do not dissolve in

water• Roles – Formation of cell

membranes – Energy source – Hormones – Vitamins

Fatty Acids• Derivative of most lipids

(structural backbone)• Consists of– glycerol (alcohol)– 3 molecules of fatty acids

• As chain length increases, insolubility in water increases

Fatty Acids• Saturated – Max number of hydrogen atoms

attached to carbons– Single bonds throughout the carbon

chain• Unsaturated– Formation of double bonds in

carbon chain– Monounsaturated – one double

bond– Polyunsaturated – many double

bonds– Causes a bent formation in molecule

Cholesterol• Formed in the liver • Structural component of plasma membrane • Function– Maintain membranes– proper membrane permeability/fluidity

• Types– LDL – low density lipoprotein • Promote cardiovascular disease

– HDL – high density lipoprotein• Good cholesterol – removes cholesterol from artery

Proteins• Each cell contains several hundred to several

thousand proteins• Composed of many amino acids linked together by

a peptide bond that form a polypeptide chain

Proteins• Structural – framework support

(Eg; hair, tendon, ligaments)• Defensive – infection fighters (Eg;

antibodies)• Signal – messenger (Eg; hormones)• Carrier – transport of materials

(Eg; hemoglobin)• Recognition and Receptor –

cellular markers (Eg; major histocompatability complex)

• Enzyme – catalyst (Eg; amylase)• Motile – movement (Eg; actin and

myosin)

Amino Acids• 20 different amino acids

– 8 essential - supplied by diet

• Contain:– Central carbon– Amino group (-NH₂)– Carboxyl group (-COOH)– R group

• R groups give each amino acids specific characteristics– Polarity, acidity

Amino Acids

Protein Structure• Primary Structure 1⁰– Linear sequence of amino acids in polypeptide chain– Changing one amino acid with change overall structure

of protein

Protein Structure • Secondary Structure 2⁰ – Polypeptides fold or coil into

patterns– Result of hydrogen bonding– β-pleated sheets• Side-by-side alignment• (Eg; strength of silk)

– α-helix • Coil that is held together by

hydrogen bonds between every 4th amino acid• (Eg; transmembrane proteins)

Protein Structure

• Tertiary Structure 3⁰– 3-D shape of a protein– Caused by folding

Protein Structure

• Quaternary Structure 4⁰– Composed of 2 or more

polypeptides– Functional proteins

Protein Denaturation• When a protein loses its 3-D structure• Often irreversible • Extreme temperatures• pH• Chemcials

Nucleic Acids• Polynucleotide chains serve as

assembly instructions for all proteins in living organisms

• 2 Types– DNA – deoxyribonucleic acid

• Stores hereditary information– RNA – Ribonucleic acid

• Hereditary molecule of some viruses

• Involved in protein synthesis

• Composed of nucleotides • Linked by a phosphodiester

bond

Nucleotides• Consists of– Nitrogenous base• Uracil (U), thymine (T), cytosine (C), adenine (A),

guanine (G)– Sugar– Phosphate groups

• Functions– Transport chemical energy– Regulate and

adjust cellular activity

DNA• Consists of – Deoxyribose sugar– Phosphate group– A, T, C, G

• Double stranded molecule (Double Helix)– Two strands of DNA run antiparallel to each other

(opposite direction)– 5’ to 3’ – 5’ is the end with the phosphate group– 3’ is where deoxyribose sugar is located

• Nitrogenous bases– Held together by hydrogen bonds– A pairs with T ( forms double bond)– C pairs with G (forms a triple bond)

• http://i-biology.net/2012/01/15/drew-berrys-animations-of-unseeable-biology-ted-talk/

RNA• Consists of– Ribose sugar– Phosphate group – A, U, C, G

• Single stranded molecule• Converts information stored in DNA into proteins