Chemical Basis of LifeChapter 2: Section 3

Organic vs. Inorganic Chemicals in the Human Body•Organic: chemicals that contain carbon

and hydrogen atoms▫Compounds dissolve in organic liquids,

such as ether or alcohol. ▫Can dissolve in water but do not release

ions and are called nonelectrolytes.•Inorganic: chemical substances that lack

carbon and hydrogen atoms.▫Dissolve/react with water to release ions;

electrolytes

Inorganic Substances

•Water•Oxygen•Carbon Dioxide•Salts

Inorganic Substances: Water• Most abundant compound in living material and

accounts for 2/3 of the weight of an adult human.• Important solvent because substances dissolve in it

▫Solute: substance dissolved in water and broken down into smaller and smaller pieces.

• Moves chemicals within the body▫Aqueous portions of blood carry substances such as

oxygen, sugars, salts, and vitamins, from digestive organs to respiratory organs.

• Can absorb and transport heat▫Blood carries heat released from muscle cells during

exercise from deeper parts to the surface.

Inorganic Substances: Oxygen

•Oxygen enters through respiratory organs and transported by blood

•RBCs bind and carry oxygen•Cellular organelles use oxygen to release

energy from sugar glucose and other nutrients.

•Released energy drives the cell’s metabolic activities

Inorganic Substances: Carbon Dioxide

•Simple, carbon-containing compound •Produced as a waste-product when

certain metabolic processes release energy, and it is exhausted by the lungs

Inorganic Substances: Salts

•Salt is a compound composed of oppositely-charged ions

•Abundant in tissues and fluids•Provide necessary compounds such as:

▫Refer to handout •Important in metabolic processes:

▫Transport of substances into and out of cells

▫Muscle contraction▫Nerve impulse conduction

Organic Substances

•Carbohydrates•Lipids•Proteins•Nucleic Acids

Organic Substances: Carbohydrates•Carbohydrates: provide much of the

energy cells require•Supply materials to build certain cell

structures and often are stored as reserve energy supplies

•Consist of carbon, hydrogen, and oxygen▫Contain twice as many hydrogen as water;

think of H2O, C6H12O6, and C12H22O11.

•Carbon atoms of carbohydrate molecules join in chains whose lengths vary with the type of carbohydrate

•Shorter chains = sugars•Sugars w/6-carbon atoms= simple sugars

or monosaccharides, and are the building blocks of complex carbohydrates▫Examples of simple sugars: glucose,

fructose, galactose

Organic Substances: Carbohydrates

•Complex carbohydrates: number of simple sugar molecules link to form molecules of varying sizes.

•Disaccharides: (double sugars) molecules contain two simple sugar building blocks▫Examples: sucrose and lactose

•Polysaccharides: made up of many simple sugar units joined together▫Example: plant starch; and animals

(humans) synthesize glycogen

Organic Substances: Carbohydrates

Organic Substances: Lipids

•Lipids: insoluble in water but soluble in certain organic solvents, such as ether or chloroform.

•Include a variety of compounds that are vital to cell functions: ▫Fats (most common)▫Phospholipids▫Steroids

•Fats: primarily to store energy for cellular activities

•Store more energy, gram for gram, than carbohydrate molecules.

•Composed of carbon, hydrogen, and oxygen atoms.▫Unlike carbohydrates, fats have a much

smaller portion of oxygen atoms.

Organic Substances: Lipids

•Building blocks of fat molecules are:▫Fatty Acids▫Glycerol

•Each glycerol binds with 3 fatty acid molecules to produce a single fat, or triglyceride, molecule.

•Glycerol portions are identical but fatty acid portions are different because there are many kinds of fatty acids.▫Variations in fatty acid chains create different

kinds of fatty acids.

Organic Substances: Lipids

•Saturated▫Each carbon atom is bound to as many

hydrogen atoms as possible and is thus saturated with hydrogen atoms

•Unsaturated▫Fatty acids with double bonds

•Polysaturated▫Fatty acids with MANY double bonds

Organic Substances: Lipids

•Like fatty acids, there are different kinds of fat molecules.

•Saturated fats▫Made of saturated fatty acids

•Unsaturated fats▫Made of unsaturated fatty acids

Organic Substances: Lipids

•Phospholipids: contains a glycerol portion and a fatty acid portion, but it only has a two fatty acid chains.

•Place for third chain is replaced by a phosphate group

•Hydrophilic head- water-loving•Hydrophobic tails- water-hating•Important in cellular structure

Organic Substances: Lipids

•Steroid: complex structures that contain 4 connected rings of carbon atoms

•Cholesterol is a very important steroid for body cells and is used to synthesize other steroids

•Other steroids include:▫Sex hormones (estrogen, progesterone,

testosterone)▫Several hormones from adrenal gland

Organic Substances: Lipids

•Protein: wide variety of functions; structural materials, energy sources, hormones.

•Glycoproteins: proteins and carbohydrates that serve as a receptor on a cell’s surface and bond to specific molecules.

•Antibodies detect and destroy foreign substances in the body.

•Enzymes make metabolism occur faster and are EXTREMELY important.

Organic Substances: Proteins

•Proteins composed of carbon, hydrogen, and oxygen, plus nitrogen and sometimes sulfur atoms.

•Building blocks of proteins are called amino acids. ▫There are 20 different kinds of amino acids

that occur commonly in living organisms.

Organic Substances: Proteins

•Protein structure:▫Primary▫Secondary▫Tertiary▫Quaternary

•Each level of structure increases complexity•Protein 3D shape = conformation•When hydrogen bonds holding protein shape

break because of heat, radiation, electricity, pH, or chemicals, the protein denatures.

Organic Substances: Proteins

•Nucleic Acids: form genes and take part in protein synthesis

•Usually large and complex molecules•Contain carbon, hydrogen, oxygen,

nitrogen, and phosphorus, which form the building blocks of nucleotides. ▫5-carbon sugar, phosphate group, and one

of several nitrogenous bases

Organic Substances: Nucleic Acids

•Two kinds of Nucleic Acids▫RNA (ribonucleic acid)

Nucleotides contain ribose Single chain but can fold into various shapes

to control when genes are accessed▫DNA (deoxyribonucleic acid)

Nucleotides contain deoxyribose Double chain that is held together by

hydrogen bonds

Organic Substances: Nucleic Acids