The most common Class II variant is the F508del variant, which is missing the 508th amino acid in the protein but has an otherwise normal sequence. Loss of this amino acid leads to misfolding of the protein, and the misfolded protein is not properly transported to the membrane. Based on this information, how many nucleotides are deleted in the CFTR allele encoding this variant?

The correct answer is - 3 (two codons of 507th that are U, C, and the first nucleotide of 508th codon U).

Explanation:

Each amino acid is coded by a three-nucleotide base long codon. So in the case of the F508del variant, there is a deletion of three nucleotides that is encoded for phenylalanine amino acid.

In this isoleucine is encoded by 507th codon that is AUG and 508th codon is UUU codes for Isoleucine.

In this case, two codons of 507th are U, C, and the first nucleotide of 508th codon U. So overall three nucleotides are deleted in the F508del variant..

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.