Transfection Process of introducing foreign DNA into animal cells Methods of transfection Microinjection, Coppt'n of DNA with calcium phosphate, liposomes, electroporation, viral vectors Liposome A spherical vesicle with a membrane composed of a phospholipid bilayer used to deliver drugs or genetic material into a cell. Since it is composed of the same material as cell membranes, it can fuse with the cell. Covalent bonds form... molecular backbones Non-covalent bond functions hold DNA together; fold polypeptides into secondary structure; enables enzymes to bind substrates; enables antibodies to bind their antigen; enables transcription factors to bind each other and DNA; enable proteins to bind their receptors; permits the assembly of macromolecular machinery (ribosomes, microtubules) Types of weak bonds H-bonds, ionic interactions, hydrophobic interactions, van der Waals forces Hydrophobic interactions Aggregation of hydrophobic molecules; can be very strong; stabilized by v.d.Waals forces; strength of these interactions are not influenced by changes in pH or salt concentration Example of a biological buffer H2CO3/HCO3- system in blood Anabolism Building molecules Catabolism Breaking down molecules Two aspects of metabolism anabolism, catabolism When ĘG is this, the reaction is spontaneous (can occur) Less than 0 When a reaction is not spontaneous, the cell compensates by... ATP hydrolysis Enzymes do this to make the reaction easier Lower the activation energy Sugars of this #Cs can form rings 5 carbons Bond formed by linkage of 2 sugars Glycosidic bond Glycosidic bonds require 2 sugars, loss of a water molecule (one sugar loses an OH, the other an H from an OH) Plant energy storage starch Animal energy storage glycogen Glycosylation Addition of sugars to proteins Addition of sugars to proteins Glycosylation Glycoproteins play important roles in: protein folding in the ER, targeting of proteins for delivery to appropriate compartment, recognition sites for cell-to-cell interaction Two types of sugar linkages in glycoproteins O-linked: attached to OH of Serine or Threonine; N-linked: attached to NH of asparagine Where glycoproteins are formed in the ER before translation is complete Lipids have these roles Storage molecules for energy; biological membranes; communication molecules (steroid hormones, membrane associated transmitters) The simplest lipid fatty acids; hydrocarbon chain with carboxyl group head Description of phospholipid Two carbons of glycerol attached to fatty acids, the other to a phosphate (which itself may be attached to other proteins such as choline, serine). This is a major substituent of membranes Cholesterol Functions of cholesterol Makes membrane more rigid (less fluid); Substrate for steroid hormones Types of transport proteins Channel proteins (create pores; porins), Carrier proteins Types of transport passive (with concentration gradient); active (requires ATP) Purines Adenine, Guanine; two ring structures Pyrimidines Cytosine, Thymine, Uracil; one ring These bonds link nucleotides Phosphodiester bonds How to monitor annealing hyperchromaticity (melting profile) Levels of RNA structure Primary - sequence of nucleotides; secondary - hairpin loops (base pairing), tertiary (motifs and 3D folding: pseudoknots - loop-loop pairing; tetraloops - 4 base hairpin loop)