Organisation of prokaryotic genome?

Question

anyone knows where can i find videos on organisation of prokaryotic genome? cos i dun understand my notes.

it says prokaryotes are haploid, stored in a single chromosome

genome is one double stranded circular, covelently closed DNA molecule.

bacterial chromosome makes up a dense region called nucleiod.

whats the difference between chromosome, nucleiod and genome?

Answer 1

I don't know of a video, but here's a shot at it.

A chromosome is a DNA molecule in its 3-D structure.  The term "bacterial chromosome" should be carefully used.  Bacterial chromosomes are not like our chromosomes.  They aren't all wound up and tightly compacted with proteins like ours.

Nucleoid is just the region in the bacterial cell where the chromosome hangs out.  Because they don't have a membrane around it, it can't be called a nucleus.

Genome is all the genetic material of an organism.  

So, the prokaryotic genome (i.e., all it's DNA) is contained in a single chromosome that is located in the nucleoid of the cell.

Here are some photos showing the nucleoid region: http://dtc.pima.edu/blc/182/lesson4/prok...

http://www.bio.miami.edu/dana/pix/prokar...

Answer 2

A chromosome is concentrated segment of DNA -- in eukaryotic cells they tend to look like x-shaped structures, and in prokaryotic cells they tend to organize into large and small circular pieces of DNA. The smaller pieces are called "plasmids" which prokaryotes can actually transfer from one cell to another (in order to share genes for evolutionary purposes).

Only prokaryotes have a "nucleiod" since they have no true nucleus -- but they really mean the same thing...that is where DNA is found in large quantities. The genome is basically the same idea as DNA.

http://faculty.ircc.edu/faculty/tfischer...