Question

17) Provide at least three ways the Central Dogma (aka “gene expression”) is different in eukaryotes versus prokaryotes and items that are conserved in both eukaryotes and prokaryotes.

18) Describe, in detail, the two ways environmental signals promote a cellular response. Include how a cell receives a signal, how it is subsequently processed, and what cellular process is targeted in order to generate the “cellular response”) Draw and/or identify the status of the lac operon in a given set of environmental conditions and/or cell mutations.

how information from DNA results in the synthesis of a protein. Explain how information in the environment ultimately results in changes to gene expression.

Answer 1

Answer 17:

Central dogma is the pathway that represents how gene expression takes place. The flow of genetic information can be shown as:

The process by which an RNA molecule is made from DNA is called transcription, whereas the process by which RNA is used as a template to make proteins is called translation.

Items that are conserved in both prokaryotes and eukaryotes:

• Same set of codons are used that specify an amino acid.
• Same 20 set of amino acids are expressed.
• Ribosomes is the site of translation.
• The first amino acid incorporated is always methionine.
• Path of information flow is the same.

Differences in gene expression in prokaryotes and eukaryotes:

Prokaryotes	Eukaryotes
Both transcription and translation takes place in the cytoplasm. The two processes generally occur simultaneously.	Transcription takes place in the nucleus, whereas translation takes place in the cytoplasm. The processes are always separated by time. (Translation follows transcription.)
Single RNA molecule may code for multiple proteins (polycistronic).	One RNA molecule can code for a single protein only (monocistronic).
No RNA processing since exon intron gene arrangement is absent.	RNA processing takes place to remove introns from naive RNA molecule.