Introduction to BioChemistry: Cellular Functions

Did you know???...  Most organisms are made up of only 6 common elements?  Within cells these few molecules are combined in many different ways to carry out a variety of functions that are the key to life.

 The invention of the electron microscope allowed scientists to study the internal structures of the cell which led to the cell theory: 1.All living things are composed of cells. 2.Cells are the smallest functional unit of life. 3.All cells come from pre-existing cells. –The cell can also be explored through chemical knowledge and procedures.

Biochemistry  The study of the chemistry of living things, including the chemical substances and processes involved.

Molecular Basis of Life  The molecules of life that nourish, build and direct cell activity include: 1.Water 2.Organic Compounds 3.Macromolecules: CarbohydratesProteinsLipids Nucleic Acids

Living Organisms Need:  H 2 O, O 2 and CO 2  Cellular Respiration is the process by which cells release energy from oxygen and simple food molecules.  What is the equation for cellular respiration?...

Cellular Respiration  C 6 H 12 O 6 + 6O 2  6CO 2 + Energy +6H 2 O  Glucose + oxygen  carbon dioxide + energy + water

Water: The Primary Molecule of Life  The most abundant molecule in any cell  Transports materials in/out of the cell.  Raw material for essential cell reactions.  Lubricant between organs, tissues and individual cells.  Remains liquid over a wide temperature range and changes temperature gradually allowing for a stable environment.  Expands when it becomes a solid.

Water molecules  These important properties of water are determined by its chemical structure.  Water molecules have an uneven charge distribution and are polar. Properties of Water

Organic Compounds  Refer to molecules that contain both carbon and hydrogen. May also contain O, N, P, S  Hydrocarbons refer to molecules containing only carbon and hydrogen.  Covalent bonds (share electrons)  Include macromolecules such as carbohydrates, lipids, proteins and nucleic acid.

Polysaccharides  A few hundred to a few thousand monosaccharides joined together.  Storage polysaccharides – Starch, Glycogen  Structural polysaccharides – Cellulose

Starch  Storage  Starch is the storage for energy in plants.  Glycogen performs the same function in animals.  Glycogen molecules hold more glucose units than starch due to their branching structure.  Examples include: Grains, Potatoes, Rice

Starch  Composed entirely of alpha glucose monomers  Two forms: amylose (unbranched) and amylopectin (branched)  In plants, sugar is stored as starch. The sugar can be held until need at which time, it can be withdrawn through hydrolysis.

Amylose

Amylopectin  Amylopectin forms branched structures with about 30 glucose units in a chain between branches.

Carbohydrates  Carbon + water  Provides short or long term energy storage  Monosaccharides (simple sugar)  Made of carbon chains that are 3- 7 carbons long  Glucose is the most common and is a 6 carbon sugar (hexoses) with the formula C 6 H 12 O 6  Trioses (3 carbon sugars) & pentoses (5 carbon sugars) are also common.  Main fuel for cellular work  When not used immediately, they are generally stored as disaccharides and polysaccharides.

Monosaccharides

Different formations of glucose

Disaccharides  2 monosaccharides joined through dehydration synthesis (water is removed)  Glucose + Glucose = Maltose (brewing of beer)  Glucose + Galactose = Lactose (milk)  Glucose + Fructose = Sucrose (table sugar)

Dehydration Synthesis

Cellulose  Structure  Cellulose is produced by plants and used as part of the cell wall.  It protects cells and provides support for the plant

Cellulose  Composed entirely of beta glucose monomers.  Parallel cellulose molecules intertwine to form strong cable structures.  Fresh fruit, vegetables and grains are rich in cellulose or fiber.

Cellulose  It also contains a large amount of energy that is not available to humans. Only a few bacterial species contain the necessary enzymes to break down cellulose, these bacteria live in the guts of cattle, rabbits and even termites. However they are not found in humans. That’s why we cannot break down food such as celery!