TP_25_Gene Regulation in Prokaryotes

8/2/2019 TP_25_Gene Regulation in Prokaryotes

http://slidepdf.com/reader/full/tp25gene-regulation-in-prokaryotes 1/17

© 2011 Pearson Education, Inc.

Gene Regulation

in Prokaryotes

Eschirichia coli (found in the intestines of most mammals) are a common model organism

used in the study of genetics.

DAY 25

Questions?




The process by which genes are “re-written” into mRNA is

known as:

1 2 3 4 5 6

17% 17% 17%17%17%17%

1. Translation

2. Transcription

3. Expression

4. Regulation

5. Repression

6. Induction




The process by which mRNA is “re-written” into an amino

acid sequence (protein or enzyme) is known as:

1 2 3 4 5 6

17% 17% 17%17%17%17%

1. Translation

2. Transcription

3. Expression

4. Regulation

5. Repression

6. Induction




The process (the central dogma of molecular biology) of a

gene making its protein product (and subsequent

phenotype) is known as:

1 2 3 4 5 6

17% 17% 17%17%17%17%

1. Translation

2. Transcription

3. Expression

4. Regulation

5. Repression

6. Induction




All genes in a single cell are continuously expressed at all

times.

1 2

50%50%

1. True

2. False




In a gene, what does the promoter nucleotide sequence

do?

1 2 3 4

25% 25%25%25%

1. Allows for the bindingof DNA polymerase toinitiate replication

2. Allows for the bindingof RNA polymerase toinitiate transcription

3. Allows the mRNA

transcript to bind to theribosome

4. Allows the translatedprotein to be activated


http://slidepdf.com/reader/full/tp25gene-regulation-in-prokaryotes 7/17© 2011 Pearson Education, Inc.

Question of the Day

How are genes turned on and off OR sped-up andslowed-down (regulated) in prokaryoticorganisms?



Where are Genes Regulated in

Prokaryotes?In bacteria, the rate of gene expression can becontrolled at three levels:

1) transcription,2) translation, or

3) post-translation (protein activation).





A Prokaryotic Model System

Sugar metabolism in Eschirichia coli

The monosaccharide glucose is the primary food source

for E. coli Genes are expressed that allow E. coli to metabolize glucose

When there is no glucose present in the environment, E.coli can use the disaccharide lactose as a secondary food

sourceGenes are expressed that allow E. coli to metabolize lactose

http://wps.prenhall.com/wps/media/objects/487/499061/CDA14_1/CDA14_1b/CDA14_1b.htm [Slide 1]

http://wps.prenhall.com/wps/media/objects/487/499061/CDA14_1/CDA14_1b/CDA14_1b.htm









The Genes that Are Involved in Lactose

Metabolism • lacZ gene – B-galactosidase

• lacY gene – Galactoside permease

• Promotors for lacI and lac operon (lacZ, lacY,lacA)

• lacI gene – regulatory protein

• Operator – regulatory site▫ http://wps.prenhall.com/wps/media/objects/487/499061/CDA14_1/CDA14_1b/

CDA14_1b.htm [Slide 2]














How is Metabolism of Glucose and

Lactose Regulated in E.Coli

Transcriptional control can be negative orpositive.

Negative control occurs when a regulatory protein prevents transcription.

Positive control occurs when a regulatory

protein increases the transcription rate.




Gene Regulation in the lac Operon

Negative Control of Gene Expression in E. coli http://wps.prenhall.com/wps/media/objects/487/499061/CDA14_1/CDA14_1b/CDA14_1b.htm [Slides 3-4]

Positive Control of Gene Expression in E. coli http://wps.prenhall.com/wps/media/objects/487/499061/CDA14_1/CDA14_1g/CDA14_1g.htm [Slides 1-6]



http://wps.prenhall.com/wps/media/objects/487/499061/CDA14_1/CDA14_1g/CDA14_1g.htm









For Next Class

• Bb Quiz #8 Due Friday, Mar 23 @ 5:00pm

▫

Topic: Sexual Reproduction & Development

• Reading: 18.1, 18.2, 18.3, 18.4, 18.5

▫ Topic: Gene Regulation in Eukaryotes

Documents

TP_25_Gene Regulation in Prokaryotes