Control of gene expression in prokaryotes takes place at the level of:
D. None of the above
Gene expression is the transfer of information from a gene to synthesise a functional gene.Prokaryotes control gene expression at the level of transcription as their organisation is simple.
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Write the different components of a lac-operon in E. coli. Explain its expression while in an ‘open’ state.Biology - Board Papers
A. What is an operon?
B. Explain how a polycistronic structural gene is regulated by a common promoter and a combination of regulatory genes in a lac-operon.Biology - Board Papers
A. Explain Polygenic inheritance and Multiple allelism with the help of suitable examples.
B. “Phenylketonuria is a good example that explains Pleiotropy.” Justify.Biology - Board Papers
(a) Why does DNA replication occur in small replication forks and not in its entire length?
(b) Why is DNA replication continuous and discontinuous in a replication fork?
(c) State the importance of origin of replication in a replication fork.
What is an operon? Explain the functioning of lac operon when in an open state.Biology - Board Papers
(a) A pea plant bearing axial flowers is crossed with a pea plant bearing terminal flowers. The cross is carried out to find the genotype of the pea plant bearing axial flowers. Work out the crossto show the conclusions you arrive at.
(b) State the Mendel’s law of inheritance that is universally acceptable.
(a) Absence of lactose in the culture medium affects the expression of a lac-operon in E. coli. Why and how? Explain.
(b) Write any two ways in which the gene expression is regulated in eukaryotes.
Biology - Board Papers