Galactosemia is a genetic disorder caused by a mutation in the DNA that codes for the enzyme galactose-1-phosphate uridylyltransferase (GALT). This enzyme normally converts galactose (a sugar found in milk) into glucose-1-phosphate.
The mutation changes the triplet codes in the DNA.
Describe how a change to the triplet codes in the DNA can prevent the enzyme from working and how this can affect the person's galactose and glucose levels.
Protein is sometimes found in the urine of people with kidney disease.
Biuret reagent is used to detect protein in the urine.
It is also used to give a measure of the concentration of protein in a sample.
Describe how the results of the Biuret test can give a measure of the concentration of protein in a sample.
72 exam-style questions on OCR GCSE Biology 1.2 What happens in cells (and what do cells need)?, covering 1.2.1 Structure of DNA, 1.2.2 Nucleotides and complementary bases, 1.2.3 Protein synthesis, 1.2.4 DNA structure and the proteins made, 1.2.5 Investigating enzymatic reactions, and 1.2.6 Mechanism of enzyme action. Each one has a worked solution and a mark scheme showing where the marks go.