Bio 1985

describe the operon hypothesis and discuss how it explains the control of messenger rna production and the regulation of protein synthesis in bacterial cells

STANDARDS:

BACKGROUND: Max. = 2 points

__ Definition of operon (functionally related genes whose expression is controlled)

__ DNA consists of genes coding for both structural and regulating proteins

(Hypothesis)

__ Authors of Hypothesis

DESCRIPTION OF OPERON (likely the Lac Operon): Max. = 8 points

Structure (diagram) Max. 4

__ promoter site

__ repressor site

__ operator site

__ structural genes

__ inducer

Function Max. 4

__ binds RNA polymerase* at 3' site on DNA (* also cAMP-CAP)

__ produces repressor protein: stops RNA polymerase attaching to promoter

__ site of attachment of repressor protein

__ codes for sequential protein

__ serves to inactivate repressor

CONTROL OF mRNA PRODUCTION & CONSEQUENCES re PROTEIN SYNTHESIS:

__ Inducible model: derepression (lactose example) [gene always off] = 3 points

__ Repressible model: corepression (tryptophan-histidine) [gene always on]

= 3 points

__ CAP model: catabolite induction: with