Chapter 07-2

Genome Structure Comparison in Eukaryotes vs Prokaryotes

Eukaryotic genomes consist of multiple linear chromosomes contained within a membrane-bound nucleus, whereas prokaryotic genomes are typically a single circular chromosome located in the nucleoid region without a nuclear membrane.

DNA Packaging and Organization Comparison

Eukaryotic DNA is tightly wrapped around histone proteins forming nucleosomes and higher-order chromatin, aiding gene regulation. Prokaryotic DNA lacks histones (except some archaea) and is compacted mainly by supercoiling without nucleosomes.

Gene Arrangement and Expression Comparison

Prokaryotic genes are often organized in operons, enabling coordinated expression of functionally related genes, with polycistronic mRNA transcripts. In contrast, eukaryotic genes are usually monocistronic, with introns present that are removed by splicing, and complex regulation involving chromatin remodeling.

Replication and Transcription-Translation Location Comparison

DNA replication and transcription occur in the nucleus of eukaryotes, with mRNA processed before translation in the cytoplasm. Prokaryotes perform replication, transcription, and translation simultaneously in the cytoplasm due to absence of a nucleus.

Genomic Content and Complexity Comparison

Eukaryotic genomes are larger, containing significant non-coding DNA including introns and repetitive elements contributing to genome complexity and regulation. Prokaryotic genomes are more compact with minimal non-coding DNA, optimizing for rapid gene expression and replication.

Plasmids and Horizontal Gene Transfer Comparison

Plasmids are common in prokaryotes as small, independent DNA molecules that enhance adaptability and can be exchanged horizontally. Plasmids are rare in eukaryotes, where gene transfer mainly occurs vertically through sexual reproduction.

Chromosomal Features Comparison

Eukaryotic chromosomes have protective telomeres at their ends and exist in multiple copies (diploid or polyploid), while prokaryotic chromosomes are generally single and circular without telomeres.

RNA Polymerase and Promoter Complexity Comparison

Eukaryotes possess multiple types of RNA polymerases and complex promoters involving many transcription factors. Prokaryotes typically use a single RNA polymerase and have simpler promoter sequences (e.g., -10 and -35 regions).