12th Grade Microbial Genetics Quizzes , Questions & Answers

Showing Quizzes for

12th Grade

Top Trending Microbial Genetics Quizzes

The Genetic Switch: Lac Operon Quiz Challenge

This assessment focuses on the lac operon, a fundamental concept in molecular biology. It evaluates your understanding of gene regulation, operon structure, and the mechanisms of lactose metabolism in bacteria. Engaging with this...

Questions: 15 | Attempts: 62 | Last updated: Mar 19, 2026

Sample Question 1
What is an operon, and why is the lac operon considered a model system for understanding prokaryotic gene regulation?

A single structural gene that codes for multiple proteins through alternative splicing in prokaryotic cells

A cluster of ribosomal RNA genes located near the replication origin of the bacterial chromosome

A regulatory protein that binds to the promoter and prevents RNA polymerase from initiating transcription

A unit of bacterial gene expression consisting of a promoter, operator, and co-regulated structural genes transcribed as a single polycistronic mRNA

Sample Question 2
What are the three structural genes of the lac operon, and what proteins do they encode?

LacI coding for lac repressor, lacP coding for a permease, and lacO coding for an operator binding protein

LacA coding for acetylase, lacY coding for permease, and lacZ coding for beta-galactosidase, all transcribed together from the lac promoter

LacZ coding for an activator protein, lacY coding for a transport enzyme, and lacA coding for a repressor that inhibits lactose uptake

LacR coding for RNA polymerase sigma factor, lacO coding for an outward-facing permease, and lacZ coding for lactose synthase

Sample Question 3
How does the lac repressor protein control transcription of the lac operon when lactose is absent from the growth medium?

The lac repressor binds directly to the sigma factor of RNA polymerase and prevents it from recognizing the lac promoter sequence

The lac repressor degrades the polycistronic mRNA after it has been transcribed, preventing translation of the structural gene products

The lac repressor methylates the lac promoter DNA, permanently silencing the operon until a demethylase enzyme is activated by lactose

The lac repressor, encoded by lacI, binds to the operator sequence overlapping the promoter and physically blocks RNA polymerase from progressing into the structural genes

12th Grade Microbial Genetics Quizzes , Questions & Answers

Top Trending Microbial Genetics Quizzes

Recent Microbial Genetics Quizzes