Genome Organization Quiz

Genome Organization

• A genome is an organism's complete set of DNA, comprising of nuclear and mitochondrial DNA, containing all the information needed to build and maintain the organism.
• Genome size is measured in base pairs and can increase by duplication, insertion, or polyploidization, or decrease due to deletions.
• Genomes of all organisms are arranged in a confined space, the nucleoid or nucleus, allowing for DNA transactions such as replication, transcription, and repair to occur at appropriate times.

Eukaryotic Genomes

• Eukaryotic genomes are arranged in the nucleus and are diploid, with DNA organized into multiple linear chromosomes.
• Eukaryotes and archaea use histone proteins, while bacteria use different proteins with similar functions.
• The primary structure of the eukaryotic genome consists of DNA wrapping around histone octamers, forming nucleosomes.
• Nucleoid proteins help maintain the supercoiled structure of the nucleic acid, distinct from histones in eukaryotic nuclei.

Eukaryotic vs. Prokaryotic Genomes

• Eukaryotes have larger genomes with fewer genes in a given length of DNA, with more noncoding DNA (10,000 times as much as prokaryotes).
• Prokaryotes have smaller genomes with more genes in a given length of DNA, with less noncoding DNA, and genes are not interrupted by introns.

Eukaryotic Genome Structure

• Eukaryotic genomes are linear and conform to the Watson-Crick Double Helix structural model.
• They have unique features of Exon-Intron organization of protein-coding genes, with intervening sequences representing RNA functionality.

Eukaryotic Genome Challenges

• The typical multicellular eukaryotic genome is much larger than that of a prokaryotic cell.
• Cell specialization limits the expression of many genes to specific cells, presenting an information-processing challenge.

Chromatin Organization

• Chromatin is the complex basis of DNA and protein that makes up chromosomes, consisting of linear, unbroken, double-stranded DNA.
• Chromatin is of two types: Euchromatin (genetically active, consisting of functional genes) and Heterochromatin (genetically inactive, with non-expressive genes).