Answer:
What role do transcription factors play in gene structure and function?
Transcription factors are proteins that bind to the upstream regulatory elements of genes in the promoter and enhancer regions of DNA and stimulate or inhibit gene expression and protein synthesis. They play critical roles in embryogenesis and development
Explanation:
Mitochondria is the powerhouse of the cell
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The right answer is vein (it contains blood and has valves).
The infra-cardiac veins of small and medium caliber possess this system of fight against gravity. The valves consist of a dense connective tissue, surmounted by endothelial cells, corresponding to a fold of the intima. They allow blood circulation in the sense organ / heart but prevent venous reflux.
Crease, could you mark brainliest? :)