Essential Cell Biology Chapter 8 Control of Gene Expression Exam Questions and Answers

Housekeeping Proteins - ANSWER-Proteins common to many cell types, concerned with basic metabolic and structural functions. Regulatory DNA Sequences - ANSWER-DNA sequence to which a transcription regulator binds to determine when where & in what quantities a gene is to be transcribed into RNA. Transcription Regulators - ANSWER-Proteins that bind specifically to a regulatory DNA sequence; involved in controlling whether a gene is switched on or off; activator or repressor. Can coordinate the expression of MANY genes. DNA Binding Motifs - ANSWER-3D substructure that is found in many proteins; bind regulatory DNA-binding proteins at enhancer/bidning/operator sites; interact with specific sequences of bases, usually through the major groove of the DNA helix. Ex. Zinc Finger, Helix-turn-helix +glucose -lactose - ANSWER-Repressor bound, Cap NOT bound; Operon OFF. +glucose +lactose - ANSWER-Cap not bound, repressor not bound; Operon OFF. Increased concentration of Allolactose. -glucose +lactose - ANSWER-Cap bound, repressor not bound; Operon ON. Cyclic AMP is produced. Lac Z, the first enzyme of the operon , encodes for the enzyme beta-galactosidase. -glucose -lactose - ANSWER-Cap bound, repressor bound. Operon OFF. Beta-galactosidase - ANSWER-Enzyme that breaks down lactose into glucose and galactose. Enhancers - ANSWER-Binding sites for activator proteins. Combinatorial Control - ANSWER-The control of gene expression in which more than one regulatory protein is used and expression is allowed only in a specific combination of conditions. The coordination of multiple proteins to initiate a SINGLE gene being transcribed. DNA Methylation - ANSWER-The addition of methyl groups (—CH3) to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.