Genetics

Methylation also plays an important role in genomic imprinting, which occurs when both maternal and paternal alleles are present but only one allele is expressed while the other remains inactive.

The biological information contained in a genome is encoded in its deoxyribonucleic acid (DNA) and is divided into discrete units called genes.

The biological information contained in a genome is encoded in its deoxyribonucleic acid (DNA) and is divided into discrete units called genes.

Because mitochondria have their own DNA, RNA, and ribosomes, this scenario is quite possible.

In 1909, Danish botanist Wilhelm Johanssen coined the word gene for the hereditary unit found on a chromosome.

There are many diseases caused by mutations in mitochondrial DNA (mtDNA).

Genes code for proteins that attach to the genome at the appropriate positions and switch on a series of reactions called gene expression.

Today we know that a single gene consists of a unique sequence of DNA that provides the complete instructions to make a functional product, called a protein.

The Physical Structure of the Human Genome

Nuclear DNA

Inside each of our cells lies a nucleus, a membrane-bounded region that provides a sanctuary for genetic information.

Genes instruct each cell type- such as skin, brain, and liver-to make discrete sets of proteins at just the right times, and it is through this specificity that unique organisms arise.