How many chromosomes do humans have ?!

[Neuron]

I have always known that humans have 46 chromosomes, but recently someone told me that we have actually 47 chromosomes. He said we have 46 nuclear chromosomes and one mitochondrial chromosome. Is this true?! Is this mitochondrial genetic information a real chromosome or does it differ in structure/function from the other nuclear chromosomes?! What does scientists say about it?! Is it counted as a chromosome ?!

[jonmoulton]

The mitochondrial chromosome is real, but differs in structure from the nuclear chromosomes. The mitochondrial chromosome resembles a bacterial chromosome.

http://en.wikipedia.org/wiki/Mitochondrion#Genome

[canalon]

And it replicates independently from the other chromosomes, not in the nucleus but within the mitochondrion.

[kolean]

Just wanted to add that chloroplast in plant cells also have a DNA component in their genetic makeup.

Mitochondrial DNA is also from the maternal oocyte, as the sperm's mitochondria do not enter the oocyte (just the nucleus does) upon fertilization.