Question

You are a researcher studying the genetics basis of colon cancer. You have been working with a colon cancer cell line to determine the expression levels of different genes that might contribute to cancer formation. You obtain the DNA methylation status of five genes of interest (the data shown in the table below.) The plus (+) sign indicates the levels of DNA methylation; more plus signs correlates with increase methylation levels....I know the answer is gene 5 but I would like to know why. Thanks

gene	Methylation levels
1	++
2	+++++
3	+++
4	++
5	+

Answer 1

DNA methylation is a process where methyl groups get added toC5 position of cytosine and forms 5methylcytocine. . This is called apigenetic changes through which expression of genes can be regulated. As a result of DNA methylation, the sequence of DNA remain unchanged but its activitiy get altered. The general function of DNA methylation is that its involved in the addition of proteins which will inhibit gene expression.

NOw, if we look at the table which shows expression level of genes which could be responsible for colon cancer. As methylation could cause suppresion of gene expression, gene 5 will be the ideal candidate as, this is showing least methylation. In the genes, where methylation rate is high, expression of genes are supposed to low. Thus gene 5 could be gene od interest which could be responsable for colon caner formation.