RetrotransposonRetrotransposons (also called class I transposable elements) are mobile elements which move in the host genome by converting their transcribed RNA into DNA through reverse transcription. Thus, they differ from class II transposable elements, or DNA transposons, in utilizing an RNA intermediate for the transposition and leaving the transposition donor site unchanged.
PolyploidyCondition where cells have more than two sets of chromosomesThis image shows haploid (single), diploid (double), triploid (triple), and tetraploid (quadruple) sets of chromosomes. Triploid and tetraploid chromosomes are examples of polyploidy.Polyploidy is a condition in which the cells of an organism have more than two paired sets of (homologous) chromosomes.
Sequence homologySequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a speciation event (orthologs), or a duplication event (paralogs), or else a horizontal (or lateral) gene transfer event (xenologs).Chromosome regionsAll chromosomes in prokaryotes and eukaryotes can be subdivided into various chromosome regions. However, the most common ones are those occurring in the chromosomes of eukaryotes, especially those that are visible in condensed chromosomes that become visible at metaphase during cell division. Each of these regions is covered in separate articles on Wikipedia. Arms (p and q) Centromere Kinetochore Telomere Sub telomere satellite chromosome or trabant.
AneuploidyAneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human somatic cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell. An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes.
DNA replicationDNA replication is the process by which a cell makes exact copies of its DNA. This process occurs in all organisms and is essential to biological inheritance, cell division, and repair of damaged tissues. DNA replication ensures that each of the newly divided daughter cells receives its own copy of each DNA molecule. DNA most commonly occurs in double-stranded form, made up of two complementarystrands held together by base pairing of the nucleotides comprising each strand.Ectopic recombinationEctopic recombination is an atypical form of recombination in which a crossing over takes place between two homologous DNA sequences located at non-allelic chromosomal positions. Such recombination often results in dramatic chromosomal rearrangement, which is generally harmful to the organism. Some research, however, has suggested that ectopic recombination can result in mutated chromosomes that benefit the organism.
Molecular evolutionMolecular evolution describes how inheritedDNA and/or RNA change over evolutionary time, and the consequences of this for proteins and other components of cells and organisms. Molecular evolution is the basis of phylogenetic approaches to describing the tree of life. Molecular evolution overlaps with population genetics, especially on shorter timescales.
DNA repairIn molecular biology, DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. A weakened capacity for DNA repair is a risk factor for the development of cancer.
DNAMolecule that carries genetic informationThe structure of the DNA double helix (type B-DNA). The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.Simplified diagramDeoxyribonucleic acid (pronunciation; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix.
GeneIn biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of RNA or protein from a gene), DNA is first copied into RNA. RNA can be directly functional or be the intermediate template for the synthesis of a protein.Slipped strand mispairingSlipped strand mispairing (SSM, also known as replication slippage) is a mutation process which occurs during DNA replication. It involves denaturation and displacement of the DNA strands, resulting in mispairing of the complementary bases. Slipped strand mispairing is one explanation for the origin and evolution of repetitive DNA sequences.*As an Amazon Associate I earn from qualifying purchases.