Question

Compare and contrast the prokaryotic and eukaryotic genomes by giving 5 similarities and 5 differences. Based on what you learned about the endosymbiont theory predict three characteristics about mitochondrial DNA.

Answer 1

Differences:

1. Prokaryotic genomes contain all coding genes as cell size is small, only essential genes are present. In eukaryotes, genomes contain introns and exons and almost 97% of the genome consists of junk DNA.

2. Prokaryotic genomes are not packaged into nucleosomes by histone proteins. Eukaryotic genomes undergo several layers of packaging necessary for DNA compaction.

3. Prokaryotic genome is circular while eukaryotic genome is composed of centromere, telomere and 2 arms.

4. Prokaryotes may or may not contain plasmid DNA which are specialised genes that can confer different properties to the cell. Eukaryotes do not contain plasmid DNA.

5. Prokaryotes do not contain transposons or repetitive DNA. Eukaryotes contain jumping genes or transposons as well as a large number of repititive DNA.

Similarities:

1. The end product of gene translation is a protein in both cell types.

2. DNA pairs up according to Chargaff's Rule of AT and GC.

3. Both cells have extrachromosomal DNA plasmid in prokaryotes and mtDNA and ctDNA in eukaryotes.

According to the endosymbiont theory, the mitochondria evolved from a symbiotic relationship between an anaerobic cell and an aerobic bacterium. Thus mitochondria have their own genetic material which replicates independantly of chromosomal DNA. Hence the DNA is circular and not linear and the type of ribosome is also different.