Lecture 1 31 Function of carbohydrates 1 As glycogen storage form of glucose in animal cells The human body can store up to 600 g of glycogen mostly and skeletal muscle cells fibers and the hepatocytes cells 2 2 Glucose is the most preferred fuel in the body cells prefer to catabolize breakdwn 3 3 In the form of glycoproteins glycolipids and glycocalyx carbohydrates act as signal glucose for energy production molecules on the surface of cells 2nd tiem of organic compound lipids Hydrophobic insoluble in water 4 types of lipids 1 Neutral fats 2 Triglycerides 3 triacylglycerols 1 Saturated fats 2 Unsaturated fats Neutral fats most common type of lipid in the human diet 2 forms of neutral fats in the diet Saturated fats Saturated fats single covalent bonds between adjacent carbon atoms is the neutral fat Solid at room temperature Usually obtained from animals fats butter Increase LDL bad cholesterol Because LDL in excess deposits cholesterol in the walls of blood vessels causing a atherosclerosis atherosclerotic plaque decrease the lumen in the blood vessels impeding blood flow resulting in high blood pressure When these atherosclerosis plaques black blood vessels then blood flow in vital organs is blocked leading to death of tissue if the blocking is in a coronary artery myocardial infarction heart attack blockage is in cerebral artery ischemic stroke Lumen space within blood vessel LDL low density lipoprotein Lipids are hydrophobic and are transported in the blood aqueous by being coated by proteins Lipid protein lipoprotein Lipid transportation in blood as lipoprotein 3 types of lipoprotein 1 VLDL a very low density lipoprotein a Will contain mostly triglycerides major lipid 2 LDL low density lipoprotein major lipid is cholesterol a You need LDL but not in excess b Transports cholesterol to cells for the synthesis of steroid hormones testosterone progesterone cortisol c LDL will transport cholesterol to plasma membranes where cholesterol is require for the maintenance of the structure of the plasma membrane fluid mosaic model of the plasma membranes d Too much LDL is bad for you e LDL atherosclerosis hence LDL bad cholesterol 3 HDL high density lipoprotein transports excess cholesterol from the blood to the liver where the cholesterol is metabolized and eliminated from the body hence HDL is referred to as the good cholesterol Fats 1 Contain at least one double covalent bond between carbon atoms 2 2 Liquid at room temperature they are referred to as oils Oils better option in the diet then saturated fats with the exception of coconut oil Which is full of saturated fats Trans fat unsaturated fats hydrogen Very bad LDL goes up more so than naturally Structure 2nd type of lipids phospholipids structures glycerol backbone 2 free fatty acid chains attached one side non polar and hydrophobic Summary Phospholipids 1 polar head phosphorous containing group and 2 non polar tails 2 free fatty acid chains Lecture 2 2 Lipids 1 Triacyl 2 Phospholipids polar heads and nonpolar tails 3 Steroids hormones which are derived from cholesterol The steroid hormones control all physiological processes occurring in the body 4 Eicoscinoids derived from an organic acid a Arachidonic acid i Cyclooxygenase used for conversion to prostaglanins ii Lipoxygenase used for conversion to leakotrienes Eicoscinoids mediate most physiological processes such as hemostasis cessation of bleeding from an injured blood vessel smooth muscle contraction 3rd organic compound proteins made up of amino acids building blocks of proteins In the human body 20 naturally occurring amino acids 2 main types of amino acids essential and nonessential amino acids Essential amino acids must be taken into the body through the diet Nonessential amino acids can be made by the body using the essential amino acids 20 naturally occurring amino acids are required for the synthesis of proteins different types of amino acids with different combinations will result in the different types of proteins in the body The type and postion of amino acids in a protein determine the overall structure of protein and hence the function of the protein structure defines function Amino acids has both an acidic end carbonyl and a basic end amino hence amino acids are referred to as amphoteric substance 4 structures levels of protein 1 Primary sequence structure type position of the amino acids which form the polypeptide chain 2 Secondary structures in human cells there are 2 types of secondary structure of proteins the alpha helix and the beta helix sheet Alpha helical structure the primary structure coils to form an alpha helix slinky Beta pleated sheets appear like ribbons the primary structures are arranged end to end to form pleats The primary structures are folded arranged end to end are held by hydrogen bonds 3 Tertiary structure of proteins some proteins attains the tertiary structure by folding the secondary structures into compact globular ball like structure with depth gives the 3 dimensional 3 D shape 4 Quaternary structure of proteins few proteins in the human cell achieve the quaternary structure this involves at least 2 primary sequences held together by Example Hemoglobin 4 chains 2 alpha and 2 beta chains 2 main classes of proteins 1 Fibrous o Insoluble in water o Extended o High tensile strength and provide mechanical support for cells o Since fibrous proteins form the structural framework of cells they are also referred to as structural proteins o Ex collagen 2 Globular o Soluble in water o Structure compact globular in shape with active sites exposed o Globular proteins involved n all physiological processes hence they are referred o Ex enzymes o Globular proteins are denatured irreversibly destroyed in the presence of low pH to as functional proteins and high temperature 4th organic compound nuclear acids the largest macromolecules in the human cells o Nucleic acids are composed of structural units called nucleotides o Each nucleotide is composed of Nitrogen containing base 5 types of such bases Thymine T Uracil U Cytosine C Guanine G Adenine A Pentose sugar Deoxyribose and ribose Phosphorous o 2 types of nucleic acids DNA RNA Cells are the structural units of all organisms life occurs in a single cell o Cellular level 2 4 Lecture Cell structure units of all organisms 3 parts of a cell o 1 Plasma membrane o 2 Cytoplasm o 3 Nucleus Plasma membrane is composed of 2 layers of phospholipids lipid bilayer Because the cell exterior are aqueous the
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