Table of Contents
Why do cells regulate protein synthesis?
Regulation of the two main steps of protein production — transcription and translation — is critical to this adaptability. Cells can control which genes get transcribed and which transcripts get translated; further, they can biochemically process transcripts and proteins in order to affect their activity.
How is DNA synthesis regulated?
In all cells studied, DNA replication is regulated by recruiting the replication machinery or “replisome” to sites called origins on the chromosome (Figure 1). The replisome is a molecular machine that replicates the DNA bidirectionally from origins in a semiconservative fashion.
How is synthesis controlled?
Gene control. The process of protein synthesis does not occur constantly in the cell, but rather at intervals followed by periods of genetic “silence.” Thus, the process of gene expression is regulated and controlled by the cell.
What regulates RNA synthesis?
Regulation of RNA synthesis In order to be transcribed, a gene must be assembled into a structurally distinct form of active chromatin. A second level of regulation is achieved by varying the frequency with which a gene in the active conformation is transcribed into RNA by an RNA polymerase.
How do cells regulate synthesis to conserve?
All cells control or regulate the synthesis of proteins from information encoded in their DNA. The process of turning on a gene to produce RNA and protein is called gene expression. The regulation of gene expression conserves energy and space.
How does attenuation regulate gene expression?
More trp operon regulation: Attenuation Like regulation by the trp repressor, attenuation is a mechanism for reducing expression of the trp operon when levels of tryptophan are high. However, rather than blocking initiation of transcription, attenuation prevents completion of transcription.
Why does chromosomes move and align themselves at the center of the cell?
During mitosis, chromosomes are bound to microtubules emanating from both poles of the mitotic spindle via sister-kinetochores and aligned on the metaphase plate precisely in the middle of the spindle. The equatorial position of the metaphase plate is a distinctive feature of metazoan, plant, and many fungal cells.
How do cells restrict DNA replication to once per cell cycle?
DNA replication is regulated by the sequential action of CDKs, coupled to S-phase cyclins and to mitotic cyclins during the cell cycle.
What controls enzyme synthesis?
Briefly, they suggested that the rate of enzyme synthesis is under the control of regulator and operator genes, with a repressor molecule in the cell cytoplasm acting as a link between the two. There are two basic systems of control, the inducible system and the repressible system.
Does RNA synthesis require A primer?
A primer must be synthesized by an enzyme called primase, which is a type of RNA polymerase, before DNA replication can occur. The synthesis of a primer is necessary because the enzymes that synthesize DNA, which are called DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides.
What inhibits protein synthesis?
Antibiotics can inhibit protein synthesis by targeting either the 30S subunit, examples of which include spectinomycin, tetracycline, and the aminoglycosides kanamycin and streptomycin, or to the 50S subunit, examples of which include clindamycin, chloramphenicol, linezolid, and the macrolides erythromycin.
How do eukaryotic cells regulate gene expression?
Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription. Other repressors compete with activators for binding to specific regulatory sequences.