Differential gene expression essentially means that
A. Each cell contains different dna.
B. Each cell type expresses different genes.
C. Different organisms express different genes.
D. All cells express all genes at low levels.
The correct answer and explanation is:
The correct answer is B. Each cell type expresses different genes.
Differential gene expression refers to the phenomenon where different types of cells within a multicellular organism express different sets of genes, even though every cell contains the same DNA. This variation in gene expression is what enables cells to differentiate and perform specialized functions.
While all cells in an organism share the same genetic material, not all genes are active in every cell type. For example, a muscle cell will express genes related to muscle contraction, while a nerve cell will express genes involved in neurotransmission. This is controlled by complex regulatory mechanisms, including transcription factors, epigenetic modifications, and RNA processing.
Gene expression can be regulated at various levels, including the transcriptional level (how much of a gene is transcribed into RNA), the translational level (how much of the RNA is used to make proteins), and the post-translational level (how proteins are modified after they are made). These regulatory mechanisms help ensure that only the necessary genes are expressed in each specific cell type.
For example, during development, stem cells differentiate into various specialized cells, each expressing a unique set of genes suited to its function. Even in adulthood, tissues like the liver, brain, and skin maintain different patterns of gene expression that allow them to perform their respective roles.
Differential gene expression is not just essential for cellular specialization but also for responding to environmental cues. When cells encounter stress, pathogens, or other stimuli, they can alter their gene expression profile to adapt and survive.