DNA

DNA Packaging Inside Nucleus Nucleosome Supercoil Protein Scaffold Chromosome

GENETIC CODE First Base in Codon Third Base in Codon Initiation Codon UGA GENETIC CODE   Initiation Codon Termination Codons U C A G UUU Phe UCU Ser UAU Tyr UGU Cys UUC UCC UAC UGC UUA Leu UCA UAA UUG UCG UAG UGG Trp CUU CCU Pro CAU His CGU Arg CUC CCC CAC CGC CUA CCA CAA Gln CGA CUG CCG CAG CGG AUU Ile ACU Thr AAU Asn AGU AUC ACC AAC AGC AUA ACA AAA Lys AGA AUG Met ACG AAG AGG GUU Val GCU Ala GAU Asp GGU Gly GUC GCC GAC GGC GUA GCA GAA Glu GGA GUG GCG GAG GGG First Base in Codon Third Base in Codon

CELL MEMBRANE Controlling what goes in and out of the cell. Anchoring of the cytoskeleton to provide shape to the cell Attaching to the extracellular matrix to help group cells together in the formation of tissues Transportation of particles by way of ion pumps, ion channels, and carrier proteins Containing receptors that allow chemical messages to pass between cells and systems Participation in enzyme activity important in such things as metabolism and immunity

CELL MEMBRANE The cell mem consists of three classes of amphipathic lipids: PHOSPOLIPIDS, GLYCOLIPIDS, STEROIDS Membrane is held together via weak non-covalent interaction of hydrophobic tails Structure is fluid and not fixed rigidly in place. Phospholipid molecules are “fluid”: free to diffuse and exhibit rapid lateral diffusion along the layer they are present in.

The FATTY ACID chains in phospholipids and glycolipids usually contain an even number of carbon atoms, typically between 14 and 24. The 16- and 18-carbon fatty acids are the most common. In animal cells, cholesterol is found dispersed in varying degrees throughout cell membranes, where it confers a stiffening and strengthening effect on the membrane. It resides in the irregular spaces between the hydrophobic tails of the membrane lipids. polar, hydrophilic heads | 7nm hydrophobic tails

SELECTIVE TRANSPORT OF MOLECULES ACROSS MEMBRANE Nutrients: in Waste: out Gate Keepers: Transmembrane PROTEINS Create: ion channels, proton pumps, etc. Extremely important to cell: e.g. a third of the genes in yeast code specifically for them Again: chicken and egg Need DNA to code for membrane proteins but Need membrane proteins to create selective membrane to allow cell to exist.