HW ans key_Ch 17 - Ch. 17 HW ans key MCQ: 1) 2) 3) 4) 5) 6)...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch. 17 HW ans key MCQ: 1) A 2) B 3) D 4) D 5) C 6) C 7) B True/ False: 1) F 2) T 3) F 4) T 5) F 6) F 7) T SQ: 1) The lac operon consists of 3 structural genes; lac Z encodes β-galactosidase, lac Y encodes permease and lac A encodes transacetylase. All 3 are transcribed as a single unit, resulting in a polycistronic mRNA. β-galactosidase cleaves lactose into galactose and glucose and also converts lactose to allolactose. Permease is necessary for the passage of lactose through E.coli cell membrane. All 3 genes have an overlapping promoter and operator region. Upstream of the lac operon is the lacI gene, which encodes the repressor. The repressor binds at the operator region and inhibits transcription by preventing RNA polymerase from binding to the promoter region. When small amount of lactose is present, β-galactosidase converts some of it to allolactose, which binds to the lac repressor. This binding alters the shape of the repressor and reduces its affinity for the operator. If the repressor does not bind to
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/04/2011 for the course BIO 325 taught by Professor Saxena during the Fall '08 term at University of Texas at Austin.

Page1 / 2

HW ans key_Ch 17 - Ch. 17 HW ans key MCQ: 1) 2) 3) 4) 5) 6)...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online