Questions: Gene Expression - Part 1 Which sentence is correct? As cells and tissues differentiate, they lose some of their genes. All cells have the same genes, but different genes are active in different cells. All cells have the same genes, and all of a cell's genes are active at the same time. Lungs look different from the heart because the cells that make up these organs have different genes.

Solution Steps

The question asks which sentence correctly describes gene expression and differentiation in cells and tissues. Let's analyze each option:

1. "As cells and tissues differentiate, they lose some of their genes." This is incorrect. Cells retain all of their genes throughout differentiation. What changes is which genes are expressed.
2. "All cells have the same genes, but different genes are active in different cells." This is correct. Differentiation occurs because different subsets of genes are transcribed and translated in different cell types.
3. "All cells have the same genes, and all of a cell's genes are active at the same time." This is incorrect. If all genes were active at all times, all cells would be the same. Gene regulation ensures that only specific genes are expressed at specific times and in specific cell types.
4. "Lungs look different from the heart because the cells that make up these organs have different genes." This is incorrect. The cells in different organs have the same genome (set of genes). The differences arise from the different genes that are expressed in each organ's cells.

Based on the analysis in Step 1, the correct sentence is: "All cells have the same genes, but different genes are active in different cells."

Final Answer