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A unit of selection is a biological entity within the hierarchy of biological organization (for example, an entity such as: a self-replicating molecule, a gene, a cell, an organism, a group, or a species) that is subject to natural selection. There is debate among evolutionary biologists about the extent to which evolution has been shaped by ...
The genetic information in a genome is held within genes, and the complete set of this information in an organism is called its genotype. A gene is a unit of heredity and is a region of DNA that influences a particular characteristic in an organism.
The function of DNA strands (yellow) alters depending on how it is organized around histones (blue) that can be methylated (green).. In biology, the epigenome of an organism is the collection of chemical changes to its DNA and histone proteins that affects when, where, and how the DNA is expressed; these changes can be passed down to an organism's offspring via transgenerational epigenetic ...
Sometimes called "jumping genes", transposons have played a major role in sculpting the human genome. Some of these sequences represent endogenous retroviruses , DNA copies of viral sequences that have become permanently integrated into the genome and are now passed on to succeeding generations.
Epigenetic mechanisms. In biology, epigenetics is the study of heritable traits, or a stable change of cell function, that happen without changes to the DNA sequence. [1] The Greek prefix epi-(ἐπι-"over, outside of, around") in epigenetics implies features that are "on top of" or "in addition to" the traditional (DNA sequence based) genetic mechanism of inheritance. [2]
In the human genome, there are three important classes of TEs that make up more than 45% of the human DNA; these classes are The long interspersed nuclear elements (LINEs), The interspersed nuclear elements (SINEs), and endogenous retroviruses. These elements have a big potential to modify the genetic control in a host organism. [30]
The gene is a unit of hereditary information that exists in many physical copies in the world, and which particular physical copy will be replicated and originate new copies does not matter from the gene's point of view. [20] A selfish gene could be favored by selection by producing altruism among organisms containing it.
A human cell has genetic material contained in the cell nucleus (the nuclear genome) and in the mitochondria (the mitochondrial genome). In humans, the nuclear genome is divided into 46 linear DNA molecules called chromosomes, including 22 homologous chromosome pairs and a pair of sex chromosomes. The mitochondrial genome is a circular DNA ...