summary of control of the prokaryotic genome Flashcards
1
Q
what are structural genes controlled by?
A
- a single promoter & operator
2
Q
where is the operator of an operon located?
A
- in between the promoter & structural genes
3
Q
what is formed after the structural genes of an operon are transcribed?
A
- a single polycistronic mRNA
4
Q
are there introns present in prokaryotic mRNA?
A
- NO, they are absent
5
Q
what is the number of proteins that can be encoded by a single polycistronic mRNA?
A
- many proteins, but ultimately depends on how many structural genes are present in the operon
6
Q
what are the proteins encoded for by the polycistronic mRNA involved in?
A
- the proteins, which are usually enzymes, are involved in the regulation of a common metabolic pathway,
- as it enables simultaneous regulation of these structural genes in response to environmental changes,
- allowing for coordinated control of the synthesis of several metabolically related enzymes
7
Q
what causes termination of transcription?
A
- a terminator at the end of the operon
8
Q
what are usually present in the upstream of each operon?
A
- regulatory genes which code for regulatory proteins that control the switching on & off of the operon
9
Q
what is the significance of organising all genes into operons in bacterial DNA?
A
- operons allow for rapid response by bacterial to environmental change,
- as an operon consists of a cluster of structural genes that are of related functions,
- the genes are transcribed at the same time since they are controlled by the same promoter & operator
- the polycistronic mRNA formed can be translated to form all the enzymes involved in the same biochemical pathway at the same time
- allowing for the rapid synthesis of important metabolites which are lacking in the environment, or the utilisation of the substrates that are present
- thus, allowing the cell to conserve its energy & resources by producing the necessary enzymes only when they are needed
