[chuckeeebeee]

Hi. My questions is do Chloroplasts contain bacterial type DNA, or do they contain bacterial type Ribosomes, or both. Thank you so much.

Chuckeeebeee!

[templelane]

They contain DNA which is exlusive to themselves and outwith the nucleus' genome. This has lead to the hypothesis that choloroplasts and indeed microchondia in animals where incorperated into cells in a endosymbiotic event.

Also the ribosomes in these organelles are smaller than the rest of the ribosomes present in the cytoplasm, but the same size as those in bacterial cells. This further supports the endosymbiotic hypothesis.

Have a read of this page
Endosymbiosis and The Origin of Eukaryotes

[jem02081]

do Chloroplasts contain bacterial type DNA

Yes, the chloroplast has a circular DNA like a bacteria & unlike the linear chromosome of eukaryotes. However the size of the chloroplast genome (100 – 300Kb) is about 1/10 the size of a bacterial genome. A lot of the chloroplast genes have “migrated” to the nuclear genome over the past say 200,000,000 years. The chloroplast method of DNA replication (starting from a single origin of replication) is also like a bacteria. Finally, the genes in chloroplasts & bacteria lack introns in the protein encoding genes in contrast to most nuclear genes.

do they contain bacterial type Ribosomes, or both.
Chuckeeebeee!

They contain only the bacterial form (70S) of the ribosome.

For the fuller picture of the science behind your questions check out Templelane’s link to Endosymbiosis and The Origin of Eukaryotes

[spyderglass]

The material within the chloroplast is called the stroma, corresponding to the cytosol of the original bacterium, and contains one or more molecules of small circular DNA. It also contains ribosomes, although most of its proteins are encoded by genes contained in the host cell nucleus, with the protein products transported to the chloroplast.

-From Wikipedia