Lecture 3 Biomolecules:
Review two of the four basic types of biomolecules:
Carbohydrates, Proteins, Nucleic Acids, Lipids. Carbohydrates: Energy in the
... [Show More] form of ATP.
Proteins: Biological catalysts, transporters, receptors, structure, antibodies, muscle.
Nucleic Acids: DNA for deoxyribonucleic acid and RNA for ribonucleic acid, information molecules.
Lipids: Structural at the cellular level.
Examples of carbohydrates and lipids in our daily lives:
Carbohydrates: Sugars, Starch, Cellulose, Simple Sugars. Proteins: Enzymes, Amino Acids.
Nucleic Acid: DNA, RNA, Nucleotides. Lipids: Fats, Oils, Glycerol, Fatty Acids. Molecules in the Cell: Carbohydrates
Simple sugars are the smallest carbohydrates.
Carbohydrates are the main source of energy from are food, or eg muscle contraction (ATP).
Simple sugars can combine to form disaccharides such as sucrose (glucose +fructose), lactose (glucose + galactose).
A large number of glucose molecules can be connected to form starch, cellulose, and glycogen. Carbohydrates also play a role in cell recognition, cell signaling, and cell adhesion.
Carbohydrates: Summary
Soluble in water, hydrophilic, they dissolve in water. Important source of energy in the cell.
Plants use part of the glucose to grow and develop but store much of it in the form of starch which can be broken down by plants or animals for energy.
If animals have too much glucose, they store it as glycogen, too much fructose is stored as fat.
Molecules in the Cell: Lipids
Insoluble in water, including fats. Oils, waxes, sterols, fat soluble vitamins. Function in structural components of cell membranes, energy storage, and signaling. Fats in animals and oils in seeds.
Saturated Fatty Acids: Contain maximum number of Hs, form straight chains, solid at room temperature.
Unsaturated Fatty Acids: Contain one or more double bonds, have a distorted structure, liquid at room temperature.
Molecules in the Cell: Cholesterol Cholesterol is a sterol
Is an important component of animal membranes, provides the correct fluidity. Substrate for many hormones, estrogen, testosterone, and cortisone.
Humans get cholesterol in three different ways 1 Diet
2 Stored cholesterol esters, and 3 Synthesis
Nearly all human tissues synthesize cholesterol Controlling Cholesterol in Humans
HMG-CoA reductase is the rate limiting enzymatic step in cholesterol biosynthesis.
Statins compete with HMG CoA. The end result is lower LDL (Low Density Lipoprotein), TG (Triglycerides) and total cholesterol levels as well as increased HDL (High Density Lipoprotein) levels.
Lipoproteins enable transport of fat molecules and cholesterol, within the water around cells and within the water based bloodstream. [Show Less]