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Homology - Diversity And Natural Selection, Homology And Computer Analysis, Exploring The Mechanisms Of Mutation, Evolutionary Relatedness

chromosome origin common homologous regions

Homology is used to describe two things that share a common evolutionary origin. In genetics and molecular biology, homology means that the sequences of two different genes or two different proteins are so similar that they must have been derived from the same ancestral gene or protein.

The word "homology" has several meanings in biology, each related to the word's origin, meaning "same knowledge." At a molecular level, the term "homology" describes sequences, either DNA or protein, that share a common evolutionary origin. On a larger scale, a pair of chromosomes from a diploid organism that have the same size and shape, are considered homologous chromosomes. Regions of each member of a chromosome pair, which carry the same set of genes, are homologous regions. Finally, physical features with a common evolutionary origin, such as the wing of bat and the hand of a human, are homologous structures.

Additional Topics

Homology - Diversity And Natural Selection

Biologists have long been fascinated by the diversity of life. The amazing variety of living things makes it natural to wonder how so many different life-forms came to be. Physical characteristics that could be easily observed, such as the shape of wing, the structure of a shell, or the size of a beak, provided the first means to search for an answer. Recognition of the variation within a species …

Homology - Homology And Computer Analysis

To study homologous sequences, researchers use computer programs, such as BLAST (Basic Local Alignment Search Tool), to compare a DNA or protein sequence with a collection of other sequences. One such collection is GenBank, the genetic sequence database operated by the NCBI that contains all publicly available DNA and protein sequences. Biologists use databases such as GenBank to find out if a tes…

Homology - Exploring The Mechanisms Of Mutation

The ability to compare protein and DNA sequences not only shows us where evolution has occurred but provides insight into its mechanisms. By comparing genomes, we find that mutations can occur on a small scale: Even a single nucleotide change is a mutation. They can also occur on a large scale, as happens when sequences are inserted, deleted, duplicated, or moved between chromosomes. Many mutation…

Homology - Evolutionary Relatedness

The number and types of differences that accumulate between genes or proteins of two different species can be used to assess their evolutionary relatedness and the amount of time since they diverged from a common ancestor. Such studies, termed "molecular systematics," can be used to show that humans are more closely related to chimps than to gorillas, for instance, and how long ago t…

Hormonal Regulation - Hormone Receptors, Nuclear Receptors And Their Hormones, Nuclear Hormone Receptors And Transcriptional Regulation, The Importance Of Hormone Concentration [next] [back] HIV - Hiv And Aids, Hiv Life Cycle: Entering Cells, Hiv Life Cycle: Reproduction, Hiv's Immune-system Impairment Mechanism

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