BIO 331 Exam 3 Questions With Correct Answers

operon - Answer a series of genes whose expression is co-regulated by controlling their common mRNA transcript lacZ gene - Answer structural gene in lac operon which codes for beta-galactosidase, to break down beta-galactosides (which includes lactose) into glucose and galactose lacY gene - Answer structural gene in lac operon which codes for permease, which transports beta-galactosides into the cell. permeases are membrane bound lacA gene - Answer structural gene in lac operon which codes for transacetylase, which detoxifies byproducts. transfers acetyl group to the beta-galactosides lacI gene - Answer gene on lac operon which codes for a regulatory protein lac regulatory protein - Answer protein that blocks transcription of lac operon structural genes when four of them are binded to the operator site allolactose (inducer) - Answer the isomer of lactose and other beta-galactosides that inactivates the lac regulatory protein and allows transcription of the structural genes IPTG - Answer an inducer of the lac operon that is not a substrate of beta-galactosidase. remains in the cell and is not broken down X-gal - Answer substrate of beta-galactosidase but is not an inducer. gets broken down but does not affect gene transcription. turns bacterial colonies blue promoter - Answer a DNA sequence that enables a gene to be transcribed operator - Answer segment of DNA that a regulatory protein binds to structural gene - Answer a gene that codes for any mRNA. does not include those that code for regulatory factors trans-acting elements - Answer DNA sequences that encode mRNA, which is translated into proteins to act on targets. includes structural genes and regulatory genes cis-acting elements - Answer DNA sequences that do not encode for mRNA but do serve regulatory roles. includes promoter and operator lac operon - Answer operon in E.coli that regulates the production of proteins involved with the digestion of lactose negative control - Answer control type where something must be removed in order for transcription to occur. Ex: lac operon