This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Total number of genes in a human being is 
Select and explain. 
A. 800000, B. 50000, C. 100000, D. 30000
D: 30000
Answer: D: 30000 
Explanation: Current estimates suggest that there are 25,000 protein-coding genes in humans. This implies that most of the DNA is non-protein-coding, i.e. its information is never translated into an amino acid sequence of a protein molecule.