BSC 219 Lecture Notes - Lecture 12: Transfer Rna, Repressor, Operon

34 views3 pages

mauveyellowjacket6

21 Apr 2017

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Gene regulation in prokaryotes genes and operons can be under negative control transcription is blocked or repressed by a regulatory molecule genes and operons can be under positive control. Transcription is stimulated or induced by a regulatory molecule this is called a repressible operon this is called an inducible operon. The lac operon metabolism is a general term describing most chemical reactions involved in living cells it can be divided into catabolism and anabolism anabolism synthesizing complex molecules. The lac operon lactose is a sugar, consisting of one molecule of glucose and one molecule of galactose lactose must be catabolized into glucose and galactose to serve as a carbon source (i. e. (cid:862)food(cid:863)) The lac operon the p region is the promoter the lac operon contains a regulatory region that can be divided into two smaller regions. The lac operon the lac operon contains a regulatory region that can be divided into two smaller regions the o region is the operator.

Related Questions

What is an operon?

What is the evolutionary advantage of an operon?

What is the difference between a repressible operon and an inducible operon?

Describe the state of the corepressor for a trp operon that is not expressing the operon gene and a lac operon that is not expressing the operon gene.

What is cell differentiation?

Name three different levels of gene regulation in a multicellular eukaryotic organism.

What is gene regulation at the chromatin level? Give one example of how it can be carried out.

Control elements are a form of gene regulation found at what level of gene regulation?

Are there forms of RNA that can block translation? If so give an example.

What do master regulatory genes have to do with control elements?

1) In the wildtype (the DNA sequence most commonly found in nature) lac operon, transcription is severely down-regulated. A mutation in lacI that causes an early stop codon in the sequence (called a lacI - strain) results in an operon that has high levels of transcription of the polycistronic m-RNA. What type of regulatory protein is the LacI protein (hint: we covered this type of protein in lecture)?

The Lac regulatory protein is called a repressor. (is this correct)

2) If a bacterium with a wildtype lac operon is grown in the presence of lactose, high levels of transcription result for a while, however, eventually transcription is again down-regulated. If, on the other hand, the sugar IPTG is present (instead of lactose), transcription levels are high and remain high. What function do IPTG and lactose share? How are they differently affected by the operon product? (need help with this question)

Lactose and IPTG affected by the operon are both inducers of the Lac-Operon. (is this correct)

3) What is âepigeneticsâ? What forms of gene regulation are usually involved in epigenetic control of a trait? Why do we have such a limited understanding of epigenetic processes? (need help with this question)

Epigenetics is the study of phenotype changes that do not change the DNA sequence. Genes can be turned on and off based on environment situations of past generations, (parents or even grandparents) were exposed. Examples of some environmental factors could be diet, stress, smoking, drinking alcohol, and diseases. Histone modification and methylation are usually involved in epigenetic control of a trait. (is this correct)

1. The lac operon of E. coli controls the expression of genes that code for enzymes involved in lactose metabolism. The operon system is inducible in that it can be âturned onâ by the presence of lactose. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products.

These mutations include:

I ^- = produces a repressor protein that can not bind to the operator region

I ^s = produces a repressor protein that can not be removed from the operator region

O ^C = can not bind a repressor protein

Z ^- = produces a defective (non-functioning) Î²-galactosidase enzyme

( I^- are recessive to I⁺; I⁺ recessive to I^S )

Detail the functionality of the lac

operon under the following genetic and cellular conditions.

GENES	Lactose present	Repressed (yes/no)	Constitutive (yes/no)	Inducible (yes/no)
I + O + Z +	no
I + O C Z +	no
I S O + Z +	yes
I - O + Z +	yes
I S O C Z +	no

sangriadolphin65

BSC 219 Lecture Notes - Lecture 12: Transfer Rna, Repressor, Operon

Document Summary

Get access

Related Documents

BSC 219 Lecture Notes - Lecture 8: Transfer Rna, Ribosomal Rna, Chromosome

BSC 219 Lecture Notes - Lecture 8: Tata Box, Cistron, Consensus Sequence

BSC 219 Lecture Notes - Lecture 22: Multiple Cloning Site, Plasmid, Restriction Digest

Related Questions