Final answer:
To estimate the number of histone H4 molecules in a 2000 bp length of DNA, calculations are based on the nucleosome structure which wraps 146 bp of DNA, containing two copies of histone H4. It is estimated that there would be approximately 26 copies of histone H4 along this DNA region.
Step-by-step explanation:
Estimating the Number of Histone H4 Molecules in a Specific DNA Length
When considering a eukaryotic gene of 2000 base pairs (bp) in length, one must understand that DNA is packed into units called nucleosomes. A single nucleosome wraps around 146 base pairs of DNA and contains eight histone molecules, including two copies of histone H4. Therefore, to estimate the number of histone H4 molecules, we divide the total length of the DNA region by the length of DNA wrapped around one nucleosome. After accounting for the nucleosome and the DNA wrapped around it, any remaining DNA would likely be in the form of linker DNA, which does not typically contain histone H4.
To estimate:
- Divide 2000 bp by 146 bp (the length of DNA wrapped by a nucleosome) which gives us approximately 13.7, rounded down to 13 complete nucleosomes.
- Since each nucleosome contains two copies of histone H4
- Multiply the number of complete nucleosomes by 2 (for the two copies of histone H4 per nucleosome)
The estimated number of histone H4 molecules would be 13 nucleosomes × 2 = 26 copies of histone H4 along the 2000 bp region of the chromosome.