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Homologous chromosome

Homologous chromosomes are the pairs of chromosomes in a diploid organism. They are the chromosomes which pair during meiosis. With the exception of the sex chromosomes, each pair has the gene loci in the same positions on each chromosome, and th ...

J1 (Y-DNA)

Haplogroup J1, more fully Y DNA haplogroup J-M267, is a Y chromosome haplogroup found in the Middle East. This means it represents a group of descendants from a single common ancestor along the fathers line. It carries a mutation on the Y chromos ...

Karyotype

A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryote cell. The term is also used of the complete set of chromosomes in a species, or an individual organism. It describes the number of chromosomes, and what they lo ...

Meiosis

Meiosis is a special type of cell division. Unlike mitosis, the way normal body cells divide, meiosis results in cells that only have half the usual number of chromosomes, one from each pair. For that reason, meiosis is often called reduction div ...

Sex linkage

Sex linkage is a term in genetics. It applies to alleles on the X chromosome. In mammals, which have an XX / XY system of sex determination, the X chromosome has many more genes than the Y chromosome. This explains the inheritance of such conditi ...

Telomerase

Telomerase is an RNA protein which is an enzyme. It adds DNA sequence repeats to the end of DNA strands in the telomere regions. The telomeres are disposable buffers blocking the ends of eukaryotic chromosomes. They are a region of repeated nucle ...

Poaching

Poaching is the illegal hunting, killing or capturing of animals. People poach because animal products, such as hide, ivory, horn, teeth and bone, are sold to dealers who make clothes, jewelry and other materials from them. The poaching causes va ...

Commensalism

Commensalism is a type of relationship between two organisms. In commensalism, one organism is helped while the other is not affected. In practice, it is difficult to show that the passive organism is not harmed. For example, some birds live in h ...

Fig wasp

Fig wasps are wasps of the superfamily Chalcidoidea which spend their larval stage inside figs. Most pollinate the figs, but others simply feed on the plant. The non-pollinators belong to several groups in the superfamily Chalcidoidea. So, the fi ...

Mutualism

Mutualism is a relationship between two organisms in which both benefit. It is a type of symbiosis which improves the biological fitness of both parties. The two organisms usually come from widely different types, often from different phyla or ev ...

Douglas Spalding

Douglas Alexander Spalding was an English biologist. He was one of the founders of ethology, but it took a long time before this was appreciated. He was born in Islington in London in 1841, and began life as a workman. Later, when he lived near A ...

Leaf insect

The family Phylliidae includes the living true leaf insects or walking leaves, which include some of the most remarkable leaf mimics in the entire animal kingdom. They occur from South Asia through Southeast Asia to Australia. There are different ...

Apomorphy

An apomorphy in biology is a derived state, or innovation. For example, amongst mammals, babies can digest their mothers milk. That is something all mammals share. It is an apomorphy unique to mammals, and so is the production of milk by mammalia ...

Crown group

A crown group is a group of living species and their ancestors back to the most recent common ancestor. It is a term in cladistics and phylogenetics. It is a clade with at least some members that have survived to the present day. How a crown grou ...

Monophyly

Monophyly means common descent from a single ancestor. Biologists have introduced a kind of taxonomy called cladistics. The aim of this is to make biological classification fit what we know about the way organisms evolved. If there is a group mad ...

Paraphyly

Paraphyly is a term in cladistics. It means a group which does not include all its descendents. So Sauropsida without birds is paraphyletic, since birds are definitely descended from archosaurs, probably small theropod dinosaurs. Paraphyly is cor ...

Polyphyly

Polyphyly is a term in cladistics. It describes a group of organisms whose last common ancestor is not a member of the group. Another way of expressing this is to say that polyphyly includes groups some members of which are descended from ancestr ...

Synapomorphy

A synapomorphy is a common character. It is a term in cladistics, meaning a trait which is present in two or more species by common descent. It is a type of homologous character or homology. More precisely, it is shared by two or more taxa and th ...

Coevolution

Coevolution is where the existence of one species is tightly bound up with the life of one or more other species. Species whose lives connect, evolve together. What happens is that survival rates in each species changes as a result of changes in ...

Evolution

Evolution is a biological process. It is how living things change over time and how new species develop. The theory of evolution explains how evolution works and how living and extinct things have come to be the way they are. The theory of evolut ...

Amylase

Amylase is an enzyme which breaks down starch into sugars which the body can use. More accurately, it is a family of similar enzymes which work in a wide range of animals, plants and fungi. There are two variants in humans: alpha-amylase, and gam ...

Convergent evolution

Convergent evolution is a process in biology. It occurs when two species from unrelated lines develop the same traits or features. This happens because they live in similar habitats, and have to develop solutions to the same kind of problems. Sim ...

Lamarckism

Lamarckism is a hypothesis regarding evolution. Evolution tries to explain how species change over time. Today, the only widely accepted theory of evolution is that developed from the ideas of Charles Darwin. Lamarckism was developed by Jean-Bapt ...

Macroevolution

Macroevolution refers to large-scale evolution. For some, this means the origin of species. For others, it means the large-scale changes seen in the fossil record. "A large evolutionary pattern. events that result in the origin of a new higher ta ...

Social responses to the idea of evolution

The idea that all life evolved was hotly debated even before Charles Darwin published On the Origin of Species. Even today, some people still talk about the concept of evolution and what it means to them, to their philosophy and their religion. S ...

Speciation

Speciation is about how species form. It is a major part of evolutionary biology. Darwin thought most species came directly from pre-existing species. This is called anagenesis: species by changing, or phyletic evolution. For much of the 20th cen ...

Balancing selection

Balancing selection refers to selective processes by which different alleles are kept in the gene pool of a population at frequencies above that of gene mutation. This usually happens when the heterozygote for a gene has a higher relative fitness ...

Epistasis

Epistasis is the interaction between genes at different loci. It was a term invented by William Bateson in 1909. When Gregor Mendel did his experiments on the sweet pea, he chose seven traits, such as round vs wrinkled peas, and tall vs short pla ...

Gene duplication

Gene duplication is any duplication of a region of DNA that contains a gene. Gene duplication is important in supplying raw genetic material – new genes – to biological evolution. This has been recognized since the 1930s. Recent genomic sequence ...

Genetic linkage

Genetic linkage occurs when alleles at different loci do not segregate at random. Mendels second law is thus broken. Genes are linked when they are on the same chromosome. They then tend to stay together during meiosis. Alleles for genes on diffe ...

Genotype

The genotype is the genetic constitution of an organism, mainly its genome. The term is contrasted with the term phenotype, as follows: genotype + environment → phenotype The terms were invented by Wilhelm Johanssen to distinguish between inherit ...

Heterozygote advantage

Heterozygote advantage is the situation where, at a gene locus, the heterozygote has greater fitness than either homozygote. p205 It is a type of balancing selection.

Inbreeding

Inbreeding is a term in genetics, meaning the crossing of closely related animals or plants. Self-fertilisation in plants is the most extreme kind of inbreeding. It is quite widespread in plants which carry both male and female flowers on the sam ...

Mendelian inheritance

Mendelian inheritance is a set of rules about genetic inheritance. The basic rules of genetics were first discovered by a monk named Gregor Mendel in the 1850s, and published in 1866. For thousands of years, people had noticed how traits are inhe ...

Mosaic (genetics)

In genetics, a mosaic means the presence of two different genotypes in an individual which developed from a single fertilized egg. As a result, the individual has two or more genetically different cell lines derived from a single zygote. Mosaicis ...

Complete Genomics

Complete Genomics, Mountain View, California, is a life sciences company which analyses DNA as a commercial service. CG has developed a commercial DNA sequencing platform for human genome sequencing and analysis. In March 2013 Complete Genomics w ...

DNA construct

A DNA construct is an artificially constructed segment of nucleic acid which is going to be transplanted into a target tissue or cell. It often contains a DNA insert, which contains the gene sequence encoding a protein of interest. The DNA insert ...

DNA repair

DNA repair means the processes by which a cell identifies and corrects damage to its DNA molecules. In cells, normal metabolic activities and environmental factors such as UV light and radiation damage DNA. There are as many as a million molecula ...

Molecular cloning

Molecular cloning is a type of work in molecular biology. It is used to assemble recombinant DNA molecules, and to direct their replication within host organisms. The use of the word cloning means a DNA molecule from a single living cell is used ...

Non-coding DNA

Non-coding DNA sequences are those parts of an organisms DNA that do not code for protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules, while others are not transcribed or give rise to RNA transcripts of ...

Promoter (genetics)

In genetics, a promoter is a section of DNA which starts the transcription of a gene. Promoters are near the genes they transcribe. They are on the same strand of DNA and are upstream. Promoters can be about 100–1000 base pairs long.

Pseudogene

Pseudogenes are genes that have lost their function. They have lost their gene expression in the cell or their ability to code protein. The term was coined in 1977. Pseudogenes can result from mutations in a gene whose product is not needed for t ...

Satellite DNA

Satellite DNA has many sections of repeating, non-coding DNA. Satellite DNA is a type of tandem repeat. The repeats sit next to each other, in tandem. These are multiple copies of the same base-pair sequence lying end-to-end. Tandem repeats also ...

Selfish DNA

Selfish DNA is a term for sequences of DNA that have two distinct properties: The DNA sequence spreads by forming additional copies of itself within the genome, and. It makes no specific contribution to the reproductive success of its host organi ...

Tandem repeat

Tandem repeats occur in DNA when a pattern of nucleotides is repeated. The repeats sit next to each other, in tandem. These are multiple copies of the same base-pair sequence lying end-to-end. An example would be: ATTCG in which the sequence ATTC ...

Genetic disorder

A genetic disorder is an illness caused by abnormalities in the genome. They are heritable, and are passed down from the parents genes. If a genetic disorder is present from birth, it is a type of congenital defect. Some only show up in later lif ...

Achondroplasia

Achondroplasia is a form of Dwarfism. It is part of the chondrodystrophies or osteochondrodysplasias family which makes bones in a humans skeleton be too short or grow too slowly. It often affects the femur and humerus. It is caused by a dominant ...

Albinism

Albinism is a condition some people and animals are born with. This condition is caused by a lack of pigment in their hair, eyes, and skin. A person or animal with albinism is called an albino. Many albino people prefer to be called a "person wit ...

Dwarfism

Dwarfism is used to describe a person of short stature, less than 4 feet, 10 inches. This is often, though not always, because of a medical condition. People with this condition are called dwarves or little people. A similar term for short people ...

Hemoglobin Lepore syndrome

Hemoglobin Lepore syndrome is a kind of blood disorder that is caused by a genetic mutation. It was first found in an Italian-American family named Lepore. When a genetic mutation runs in families it is known as a trait. The Hb Lepore trait is fo ...

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Pino - logical board game which is based on tactics and strategy. In general this is a remix of chess, checkers and corners. The game develops imagination, concentration, teaches how to solve tasks, plan their own actions and of course to think logically. It does not matter how much pieces you have, the main thing is how they are placement!

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