Gene Expression

what does each somatic cell in the body generally contain

the same DNA, with exceptions like red blood cells and some immune cells

why does the differentiation in cell types arise

not all genes are expressed in every cell

what happens during the process of gene expression

specific genes are transcribed into RNA and then translated into proteins, enabling cells to perform their unique functions

what does Eukaryotic gene expression involve

multiple regulation stages, including transcriptional, post-transcriptional, translational, and post-translational control

what is the regulation of gene expression is crucial for

energy conservation and spatial efficiency, as expressing every gene at all times would be energetically wasteful

what does energy conservation and spatial energy involve

complex networks of internal chemical mechanisms that control when and how genes are expressed

In prokaryotic cells…

gene expression occurs simultaneously through transcription and translation

Prokaryotic gene regulation primarily occurs at what level

transcription level

In eukaryotic cells…

gene regulation encompasses several levels, including the chromatin structure changes (epigenetic control), transcription factors binding, mRNA processing, and protein modifications after translation

what do enhancers and promoters do

play vital roles in gene activation or repression

Cancer is often characterized by…

altered gene expression, including mutations in tumor-suppressor genes and proto-oncogenes

what can mutations in tumor suppressor genes cause

uncontrolled cell growth, resulting from various alterations at different levels of gene expression regulation, making cancer a disease of gene expression

what do all somatic cells within an organism contain

same DNA, but not all cells express the same proteins

Prokaryotes vs. Eukaryotes

Prokaryotic organisms express most of their genes most of the time, with some expressed only when needed. Eukaryotic organisms express only a subset in any given cell

what does the Gene Expression Process involve

transcription (DNA to RNA) followed by translation (RNA to proteins) targeted to specific cellular locations

transcription and translation in prokaryotic and eukaryotic cells

In prokaryotic cells, transcription and translation are simultaneous; in eukaryotic cells, transcription occurs in the nucleus and translation occurs in the cytoplasm

Regulation Levels prokaryotic vs eukaryotic

Gene expression in prokaryotes is mainly regulated at the transcriptional level, while eukaryotic regulation occurs at epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels

what is a trp Operon

Repressor activated by tryptophan; transcription off if not needed

what does a lac Operon require

binding of lactose to inactivate the repressor, enabling transcription when glucose is absent and lactose is present

what are Chemical Modifications

Modifications to histone proteins and DNA signal gene accessibility, impacting the binding of RNA polymerase and transcription factors

what does Initiation require

general transcription factors to bind to the TATA box and recruit RNA polymerase. Additional factors may enhance or prevent transcription

Enhancers…

Can be located in various positions and are crucial for increasing transcription levels

Control Post-Transcription

Control occurs during RNA splicing and stability. Introns are removed, and exons are ligated by spliceosomes

what does Alternative Splicing allow

multiple mRNA from one transcript, varying based on conditions

RNA Transport

Transferred to the cytoplasm for translation via nuclear pore complex. RNA stability is modified to control synthesis amounts, influenced by RNA-binding proteins and microRNAs

what does Protein Synthesis require

formation of a protein initiation complex. Modifications can hinder translation

what does Post-translational Modifications include

phosphorylation, acetylation, methylation, and ubiquitination affecting protein stability and function

Cancer as Altered Gene Expression

Characterized by changes in gene expression across all levels of regulation in cells. Understanding these mechanisms in normal cells is essential to pinpoint how they malfunction in disease, notably in cancer