Gene expression

Definition

Gene expression is the process by which information from a gene is used to synthesize functional gene products, usually proteins, which then carry out various functions in the cell. This process is fundamental to all cellular activities, affecting how cells respond to their environment, differentiate, and maintain homeostasis. It is closely linked to biochemical processes, the role of biomolecules in cellular functions, signaling pathways, and the steps of transcription and translation.

5 Must Know Facts For Your Next Test

1. Gene expression can be regulated at multiple levels, including transcriptional, post-transcriptional, translational, and post-translational modifications.
2. Transcription factors are proteins that bind to specific DNA sequences to enhance or inhibit the transcription of genes, playing a key role in regulating gene expression.
3. The central dogma of molecular biology outlines the flow of genetic information from DNA to RNA (transcription) and from RNA to protein (translation), illustrating the core processes involved in gene expression.
4. Signal transduction pathways can influence gene expression by activating or repressing transcription factors in response to external signals like hormones or growth factors.
5. Mutations in regulatory regions of DNA can lead to abnormal gene expression patterns, which may result in diseases such as cancer.

Review Questions

• How does the regulation of transcription factors impact gene expression in cellular processes?
  • Transcription factors are critical regulators of gene expression as they bind to specific DNA sequences near genes and either promote or inhibit their transcription. By influencing which genes are turned on or off, transcription factors help determine cell fate and function. This regulation plays a vital role in processes such as differentiation, response to environmental changes, and maintaining homeostasis within the cell.
• Discuss the relationship between signal transduction pathways and gene expression, providing examples of how external signals can alter cellular responses.
  • Signal transduction pathways facilitate communication between cells and their environment, enabling external signals to influence cellular behavior. For example, when a growth factor binds to its receptor on the cell surface, it triggers a cascade of intracellular events that can lead to the activation of specific transcription factors. These activated transcription factors then promote the expression of genes involved in cell growth and division. This demonstrates how external stimuli can dramatically alter gene expression and cellular outcomes.
• Evaluate the role of epigenetics in gene expression regulation and how it contributes to phenotypic diversity without altering DNA sequences.
  • Epigenetics plays a crucial role in regulating gene expression by introducing heritable changes that do not involve modifications to the underlying DNA sequence. Mechanisms such as DNA methylation and histone modification can silence or activate genes in response to environmental cues. This allows for phenotypic diversity within populations without changes in genetic makeup. Such epigenetic modifications can affect an organism's adaptability to changing environments and have implications for development and disease.

Related terms

Transcription: The first step in gene expression where the DNA sequence of a gene is copied into messenger RNA (mRNA).

Translation: The process following transcription where mRNA is decoded by ribosomes to produce a specific polypeptide or protein.

Epigenetics: The study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence, often influenced by environmental factors.