20 Questions
What is the primary function of gene regulation in a cell?
To control which genes are expressed
What is the main difference between cells in a multicellular organism?
The set of genes they express
What determines the unique properties of a cell?
The set of genes expressed
At which stage of gene expression can regulation occur in eukaryotes?
At any of the multiple steps
What is the primary level at which gene regulation occurs in many genes?
Transcription
What is the purpose of gene regulation in cells?
To control which genes are expressed
Why do different cell types have different sets of active genes?
Because they express different sets of genes
What is the role of liver cells in the body?
To remove toxic substances from the bloodstream
What is the enzyme produced by liver cells that breaks down alcohol?
Alcohol dehydrogenase
What is the result of different patterns of gene expression in cells?
Different sets of proteins and functional RNAs
What is the main reason why neurons in a person's brain do not remove toxins from the body?
Because genes for toxin removal are turned off
What determines a cell's gene expression pattern?
A combination of internal and external information
What happens when a growth factor binds to a receptor protein on the cell surface?
The receptor protein changes shape, triggering a series of chemical events
What is the result of transcription factors binding to specific DNA sequences?
The promotion or repression of gene transcription
At which stages can eukaryotic gene expression be regulated?
At multiple stages, from chromatin accessibility to protein synthesis
What affects the lifetime of an mRNA molecule in the cytosol?
RNA stability
What is the result of alternative splicing?
The production of different mRNAs from the same pre-mRNA
What is the function of transcription factors in gene regulation?
To promote or repress transcription
What is the term for the structure of DNA and its organizing proteins?
Chromatin
What is the term for a chemical signal from a neighboring cell that instructs a target cell to grow and divide?
Growth factor
Study Notes
Gene Regulation
- Gene regulation is the process of controlling which genes in a cell's DNA are expressed to make a functional product such as a protein.
- Different cells in a multicellular organism may express very different sets of genes, despite having the same DNA.
- The set of genes expressed in a cell determines the set of proteins and functional RNAs it contains, giving it its unique properties.
Gene Expression
- Gene expression involves many steps, and gene regulation can occur at any of these steps.
- Many genes are regulated primarily at the level of transcription.
- Gene regulation is crucial for cells to have different sets of active genes, despite having the same DNA.
Cell Specialization
- Different patterns of gene expression cause cells to have different sets of proteins, making each cell type uniquely specialized to do its job.
- Example: liver cells express genes encoding subunits of an enzyme called alcohol dehydrogenase to break down alcohol, while neurons in the brain do not.
Factors Influencing Gene Expression
- A cell's gene expression pattern is determined by information from both inside and outside the cell.
- Examples of internal information: proteins inherited from the mother cell, DNA damage, and ATP levels.
- Examples of external information: chemical signals from other cells, mechanical signals from the extracellular matrix, and nutrient levels.
Cellular Response to Signals
- Cells respond to signals, such as growth factors, through molecular pathways that convert information into a change in gene expression.
- Example: growth factor binding to a receptor protein triggers a series of chemical events that activate transcription factors, leading to transcription of cell division-related genes.
Regulation of Eukaryotic Gene Expression
- Eukaryotic gene expression can be regulated at many stages, including chromatin accessibility, transcription, RNA processing, RNA stability, translation, and protein activity.
- Different genes are regulated at different points, and it's common for a gene to be regulated at multiple steps.
- Chromatin accessibility, transcription, and RNA processing are key regulatory points for many genes.
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