Stuck on a Question

[Pumpion]

Right now I'm working on the Chapter Review questions from Heinemann Biology 2 5th Edition and I'm having some trouble with Question 16.
"In Section 3.2 you learnt that the longest known gene is the dystrophin gene which is 2.5 megabases long and that this gene is 99% introns.
a. What is the maximum number of bases in the exons of the dystrophin gene?
b. How many amino acids (approximately) make up the protein dystrophin?"
The teachers I've asked at school haven't known, and my teacher isn't very helpful, so can someone please help? Thanks!

[sweetcheeks]

I had never heard the term megabase before, so I looked it up, so I am not 100% on this information.

1 megabase is the equivalent of 1 000 000 (one million) base pair lengths (that is the strand of DNA has a length of 1 million bases/nucleotides).

2.5 megabases means that the strand is going to be 2 500 000 (2.5 million) nucleotides in length. If 99% of the gene is introns that means that 1% of the gene is composed of exons. To find the amount of exon bases you need to find 1% of 2.5 million. This can be done by going 0.01 x 2,500,000. This gives us a length of 25000 nucleotides

As for amino acids. The introns code for a protein. Every 3 base pairs (codon) will code for 1 amino acid, except for the last codon which initiates the stop sequence (this is the stop codon). Work out how many nucleotides make up the intron section and divide by 3. Round to a nice number (I would ignore the stop codon)