Related Concept Videos
00:58Genomic DNA in Eukaryotes
Eukaryotes have large genomes compared to prokaryotes. To fit their genomes into a cell, eukaryotic DNA is packaged extraordinarily tightly inside the nucleus. To achieve this, DNA is tightly wound around proteins called histones, which are packaged into nucleosomes that are joined by linker DNA and coil into chromatin fibers. Additional fibrous proteins further compact the chromatin, which is recognizable as chromosomes during certain phases of cell division.
02:02Genomics
Genomics is the science of genomes: it is the study of all the genetic material of an organism. In humans, the genome consists of information carried in 23 pairs of chromosomes in the nucleus, as well as mitochondrial DNA. In genomics, both coding and non-coding DNA is sequenced and analyzed. Genomics allows a better understanding of all living things, their evolution, and their diversity. It has a myriad of uses: for example, to build phylogenetic trees, to improve productivity and...
02:54Evolutionary Relationships through Genome Comparisons
Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is that if two species share a common feature, it is likely encoded by the DNA sequence conserved between both species. The advent of genome sequencing technologies in the late 20th century enabled scientists to understand the concept of conservation of domains between species and helped them to deduce evolutionary relationships across diverse...
03:36Genome Annotation and Assembly
The genome refers to all of the genetic material in an organism. It can range from a few million base pairs in microbial cells to several billion base pairs in many eukaryotic organisms. Genome assembly refers to the process of taking the DNA sequencing data and putting it all back together in a correct order to create a close representation of the original genome. This is followed by the identification of functional elements on the newly assembled genome, a process called genome annotation.
01:26Size and Structure of Viral Genomes
Viral genomes exhibit remarkable diversity in size, structure, and composition, influencing their replication strategies and interactions with host cells. These genomes consist of either DNA or RNA and may be linear or circular. Additionally, they can be single-stranded or double-stranded, with each configuration affecting how the virus propagates within a host. RNA viruses, for instance, generally have smaller genomes than DNA viruses, a factor that contributes to their high mutation rates and...
01:08Evolution of Microbial Genome
Microbial genome evolution is a highly dynamic process shaped by continual gene gain and loss across species and strains. This genomic flexibility allows microorganisms to adapt rapidly to environmental pressures and interactions with other organisms. Central to understanding this diversity is the distinction between the core and pan genomes.The core genome comprises the genes shared by all sampled strains of a species, representing essential functions needed for fundamental cellular processes.
You might also read
Related Articles
Articles linked to this work by shared authors, journal, and citation graph.
Sort by
Same author
A mosaic of modular variation at a single gene underpins convergent plumage coloration.
Science (New York, N.Y.)·2025
Related Experiment Video
Updated: Jun 4, 2026
11:13
RNA-Seq Analysis of Differential Gene Expression in Electroporated Chick Embryonic Spinal Cord
Published on: November 1, 2014
How complete are "complete" genome assemblies?-An avian perspective.
Valentina Peona1, Matthias H Weissensteiner1,2, Alexander Suh1
1Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
Molecular Ecology Resources
|July 24, 2018
Summary
Current genome assemblies for nonmodel vertebrates, like birds, often miss substantial portions of DNA, particularly GC-rich and repetitive regions. Long-read sequencing improves completeness but gaps remain, necessitating combined technologies for accurate population genetics.
Area of Science:
- Genomics
- Bioinformatics
- Comparative Genomics
Background:
- The genomics revolution has produced numerous "complete" genome assemblies for nonmodel organisms.
- However, the completeness of these assemblies, particularly for vertebrates like birds, is often overestimated.
- Short-read sequencing technologies frequently miss significant portions of the genome (7-42%).
Discussion:
- Repetitive DNA and guanine-cytosine (GC)-rich regions are consistently underrepresented in genome assemblies.
- Long-read sequencing technologies have shown promise in characterizing these previously inaccessible regions.
- Even advanced assemblies like the latest chicken reference (galGal5) still contain thousands of gaps, often in centromeric regions due to long repetitive DNA arrays.
Key Insights:
- Short-read sequencing misses 7-42% of expected genome size in nonmodel vertebrates.
- Long-read sequencing significantly improves the assembly of GC-rich and repetitive DNA regions.
- Assembly gaps, especially in centromeres, persist due to technological limitations in resolving extremely long repetitive sequences.
Outlook:
- Combining short-read and long-read sequencing technologies can minimize assembly gaps.
- Accurate characterization of assembly gaps is crucial for reliable population genetic inferences.
- Future research should focus on bridging remaining gaps to achieve more contiguous and complete genome assemblies.