Biology 1202B Lecture Notes - Lecture 14: Pepsin, Oncogene, Alternative Splicing
Document Summary
All cells have the same complement of dna (in a single organism) Yet cells of different type are vastly different. Different expression of the same set of genes. Differences are a result of regulation of gene expression (primarily transcription) Requires energy to transcribe/translate and is energy-costing; does not require if not needed. Tend to be single celled and relatively simple. React and adapt to changes in environment. Manufacture the simple products needed for (brief) survival and reproduction. Synthesizing depends on what is available in the immediate environment; no synthesizing required when there"s availability. Depending on what is available they turn on/off various biochemical pathways. Cluster of genes and the dna sequences involved in their regulation. E. coli lac operon lactose metabolism. Glucose is preferred sugar: turned on when glucose not available but lactose is. Operon is uncontrolled because e. coli will take glucose (preferred sugar) Lactose needs to be broken down to glucose and galactose to obtain energy.