Introductory Biochemistry

Week 3

Chemistry

Science of structure and interactions of matter

Matter

Anything that occupies space and has mass

Mass

Representation of the amount of matter in something

Element

A substance that cannot be broken down into simpler substances

Chemical Elements in Human Body

• Contains 26 elements

• 96% of body’s mass is made up of oxygen, carbon, hydrogen and nitrogen

Atom

Smallest unit of matter that retain properties and characteristics of an element

Nucleus

Core of atom made up of protons and neutrons

Ion

Atom that has a charge due to unequal number of protons and electrons

Ionization

Process of losing or gaining an electron

Molecule

Two or more atoms of the same element share electrons

Compound

A molecule that is formed from atoms that are different from each other

Electrolytes

• A substance that dissociates in water into ions

• Nerve and muscle function, maintains body fluid levels and pH regulation

Cation

Positively charged ion

Anion

Negatively charged ion

Ionic Bond

• An atom loses its electron and gives it to another atom

• Atoms with stronger affinity attract electrons away from atoms with weaker affinity

• Opposite charges attract ions together

• Metal and non-metal

• Moderate strength

Covalent Bond

• Atoms share electrons

• Happens in atoms that have unstable electron configuration

• Non-metal and non-metal

• Strongest bond

Hydrogen Bond

• Partially positive charged hydrogen atom attracts partially negative charged atom (H2O)

• Weakest bond

Law of Conservation of Energy

Energy/matter cannot be created or destroyed but can be converted to another form

Metabolism

All chemical reactions in the body

Potential Energy

Energy stored by matter due to its position (water behind dam)

Kinetic Energy

Energy in matter in motion (Gates of dam open)

Chemical Energy

Potential energy stored in bonds

Exergonic Recction

Releases more energy than it absorbs

Endergonic Reaction

Absorbs more energy than it releases

Catalyst

Chemical compounds that speed up chemical reactions by lowering activation energy required

Activation Energy

Energy needed to break chemical bond

Synthesis Reaction

• Atoms, ions or molecules combine to form new larger molecules

• Synthesis reactions in body are known as anabolism

• Typically endergonic

Decomposition Reaction

• Split up larger molecules into smaller atoms, ions or molecules

• Decomposition reactions in body are known as catabolism

• Typically exergonic

Exchange Reaction (DD)

Consist of both synthesis and decomposition reactions

Reversible Reaction

Products can revert back to original reactants. Required certain conditions for reaction to go a certain direction

Exothermic

Releases heat energy

Endothermic

Absorbs heat energy

Inorganic Compounds

• Typically lack carbon and are structurally simple

• Ionic or covalent bonds

Organic Compounds

• Always contain carbon, typically contains hydrogen

• Covalent bonds

Solvent

Able to dissolve other substances

Solute

Substance that dissolves in solvent

Solution

Liquid mixture of solvent and solute

Hydrophilic

• Dissolve easily in water

• Solutes that are charged or contain polar covalent bonds

Polar Covalent Bonds

Share electrons unequally (no overall charge)

Hydrophobic

• Do not dissolve easily in water

• Solutes that contain non-polar covalent bonds

Non-polar Covalent Bonds

Shares electrons equally

Hydrolysis

Chemical breakdown of substance using water (Digestion)

Dehydration Synthesis Reaction

Two smaller molecules join together to create larger molecule, byproduct is water (Protein synthesis)

Importance of Water - Thermal Properties

• Water can absorb and release a relatively large amount of heat with only a modest change in its own temperature

• Water absorbs heat energy, energy breaks down hydrogen bonds, little remaining energy to increase the motion of water molecules

• Has a high heat capacity due to large number of hydrogen bonds

Importance of Water - Lubricant

Major component of mucus and other lubricating fluids throughout the body (body cavities, joints, GI tract)

Carbohydrates

• Includes sugars, glycogen, starches and cellulose

• Primary function as a source of energy for generating ATP

Monosaccharides

Simple sugars (glucose and frutose)

Disaccharides

Simple sugar, two monosaccharides (sucrose)

Polysaccharides

Tens/hundreds of monosaccharides (glycogen)

Lipids

Most are hydrophobic

Fatty Acids

• Simplest lipids used to synthesize triglycerides and phospholipids

• Can be catabolized to generate ATP (produces keytones)

Triglycerides

Most plentiful in body, fats and oils, high concentrated stores of energy

Phospholipids

• Forms cell membranes

• Contains phospholipid bilayer: Hydrophilic head and hydrophobic tail

Steroids

• Cholesterol, estrogen, testosterone, cortisol, aldosterone

• Chemical/hormone regulation

Proteins

Large and complex molecules that are largely responsible for the structure of body tissues

Amino Acids

• Building blocks for proteins

• 50-2000 amino acids joined end to end via peptide bonds

Polypeptides

Chained amino acids

Enzymes

• Catalyst proteins. (Suffix “ase”) - amylase, lipase, etc

• Catalyze specific reactions - highly targeted, binds to specific substrate (reactant molecule) lock and key

• Lowers the activation energy of a chemical reaction

Nucleic Acids

First discovered in the nuclei of cells

Deoxyribonucleic Acid (DNA)

• Forms the inherited genetic material inside each human cell

• Determine the traits we inherit

Ribonucleic Acid (RNA)

Relays instructions from genes to guide synthesis of proteins from AA

Adenosine Triphosphate (ATP)

• Energy currency of living organisms

• Transfers the energy liberated in exergonic catabolic reactions to power cellular activities that require energy (endergonic)

Cellular Respiration

• Catabolism of glucose (within the cell) to produce CO2, H2O and ATP

• Anaerobic (without O2) and aerobic (with O2)