Genomes and Their Evolution

GenomicsThe study of whole sets of genes and their interactions. Bioinformatics The use of computer modeling and computational methods to the storage and analysis of biological data. All about S.T.E.M. Human genome project Sequencing of the entire human genome. Began in 1990 and completed in Sequencing machines were used to determine the complete nucleotide sequence of each chromosome. Advances in the field of Genetics Metagenomics DNA from a group of species (metagenome) is collected from an environmental sample and sequences using computer software. It eliminates the need to culture each species separately. Intestine

The BLAST software program available to the public on the NCBI website allows the visitor to compare a DNA sequence with every sequence in the GenBank, base by base, to look for similar regions. BLAST is updated constantly from around the world.

ProteomicsThe study of whole protein sets encoded by genomes. Systems biology Shifting attention from individual parts to to their functional integration in biological systems. Example - The Cancer Genome Atlas. Systems biology

Microarray Machines arrange minuscule amounts of thousands of gene sequences on a microscope slide. When a gene is activated, cellular machinery begins to copy certain segments of that gene, producing mRNA. The mRNA produced by the cell is complementary, and therefore will bind to the original portion of the DNA strand from which it was copied. Microarray technology will help researchers to learn more about many different diseases, including heart disease, mental illness and infectious diseases, and cancer. Microarray technology lets researchers classifytypes of cancers based on patterns of gene activity enabling them to design treatment strategies targeted directly to each specific type of cancer.

Non-Coding DNA and Multigene Families Only 1.5% of the human genome codes for proteins or gives rise to rRNAs or tRNAs; the rest is noncoding DNA, including pseudogenes and repetitive DNA of unknown function. Pseudogenes are genomic DNA sequences similar to normal genes but non- functional; they are regarded as defunct relatives of functional genes. Pseudogenes Transposons/retrotransposons used to be considered “junk” DNA, but are now thought to to be important in genome function and evolution. The most abundant type of repetitive DNA in multicellular eukaryotes consists of transposable elements and related segments. Transposons, which move via a DNA intermediate, and retrotransposons, which are more prevalent and move via an RNA intermediate. families.

NonCoding DNA and Multigene Families Other repetitive DNA includes short noncoding sequences that are tandemly repeated thousands of times; these sequences are especially prominent in centromeres and telomeres, where they probably play structural roles in chromosomes. Though many eukaryotic genes are present in one copy per haploid chromosome set, others are members of a family of related genes, such as the human globin gene families.

Genome Evolution Accidents in cell division can lead to extra copies of all or part of an entire chromosome sets, which may then diverge if one set accumulates sequence changes. The chromosomal organization of genomes can be compared among species, providing information about evolutionary relationships. Within a species, rearrangements of chromosomes are thought to contribute to the emergence of new species.

Genome Evolution The genes encoding the various globin proteins evolved from one common ancestral globin gene, which duplicated and diverged into alpha globin and beta globin ancestral genes. Subsequent duplication and random mutation gave rise to the present globin genes. All of which code for oxygen-binding proteins. The copies of some duplicated genes have diverged so much that the functions of their encoded proteins are now substantially different.

Genome Evolution Each exon may code for a domain, a discrete structural and functional region of a protein. Rearrangement of exons within and between genes during evolution has led to genes containing multiple copies of similar exons and/or several different exons derived from other genes. Movement of transposable elements or recombination between copies of the same element can generate new combinations that are beneficial to the organism, which can alter the functions of genes or their patters of expression and regulation.

Genome Evolution Comparative studies of genomes from widely divergent and closely related species provide valuable information about ancient and more recent evolutionary history, respectively. Evolutionary developmental biologists have shown that homeotic genes and some other genes associated with animal development contain a homeobox region whose sequence is highly conserved among diverse species. Related sequences are present in the genes of plants and yeasts.