A microsatellite null allele is an allele at a microsatellite locus that does not amplify to detectable levels in a polymerase chain reaction test. Divergence from the reference sequences from genetic mutations results in poor annealing of the primers so that the marker cannot be used, representative of a null allele. Strong evidence of null alleles was first seen in analysis of bears in Null alleles or genes have been studied in different organisms from the red pines of Minnesota to Drosophila melanogaster and mice.
Null alleles are difficult to identify because a heterozygous individual for one null allele and one active allele is phenotypically indistinguishable from a homozygous individual with both active alleles. Researchers have been able to work around this problem by using detailed Electrophoresis , gel assays, and chromosomal manipulation. An allele is one of two, or more, forms of a given gene variant.
Nearly every living human's phenotype for the ABO gene is some combination of just these six alleles. An allele is one of two, or more, versions of the same gene at the same place on a chromosome.
It can also refer to different sequence variations for several-hundred base-pair or more region of the genome that codes for a protein. Alleles can come in different extremes of size. At the lowest possible size an allele can be a single nucleotide polymorphism SNP. At the higher end, it can be up to several thousand base-pairs long.
Most alleles result in little or no observable change in the function of the protein the gene codes for. Microsatellites occur at thousands of locations within an organism's genome. They have a higher mutation rate than other areas of DNA leading to high genetic diversity. Microsatellites are often referred to as short tandem repeats STRs by forensic geneticists and in genetic genealogy, or as simple sequence repeats SSRs by plant geneticists.
In genetics, dominance is the phenomenon of one variant allele of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes autosomes and their associated traits, while those on sex chromosomes allosomes are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child.
Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant nor recessive. Additionally, there are other forms of dominance such as incomplete dominance , in which a gene variant has a partial effect compared to when it is present on both chromosomes, and co-dominance , in which different variants on each chromosome both show their associated traits. A gene knockout is a genetic technique in which one of an organism's genes is made inoperative.
However, KO can also refer to the gene that is knocked out or the organism that carries the gene knockout. Knockout organisms or simply knockouts are used to study gene function, usually by investigating the effect of gene loss. Researchers draw inferences from the difference between the knockout organism and normal individuals. Genetic variation is the difference in DNA among individuals or the differences between populations.
There are multiple sources of genetic variation, including mutation and genetic recombination. Mutations are the ultimate sources of genetic variation, but other mechanisms such as sexual reproduction and genetic drift contribute to it as well. A heterozygote advantage describes the case in which the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype.
The specific case of heterozygote advantage due to a single locus is known as overdominance. Overdominance is a condition in genetics where the phenotype of the heterozygote lies outside of the phenotypical range of both homozygote parents, and heterozygous individuals have a higher fitness than homozygous individuals.
Equine coat color genetics determine a horse's coat color. Many colors are possible, but all variations are produced by changes in only a few genes.
Extension and agouti are particularly well-known genes with dramatic effects. Differences at the agouti gene determine whether a horse is bay or black, and a change to the extension gene can make a horse chestnut instead. Most domestic horses have a variant of the dun gene which saturates the coat with color so that they are bay, black, or chestnut instead of dun, grullo, or red dun. A mutation called cream is responsible for palomino, buckskin, and cremello horses.
Pearl, champagne and silver dapple also lighten the coat, and sometimes the skin and eyes as well. Genes that affect the distribution of melanocytes create patterns of white such as in roan, pinto, leopard, white, and even white markings. Finally, the gray gene causes premature graying, slowly adding white hairs over the course of several years until the horse looks white. Some of these patterns have complex interactions. Non-Mendelian inheritance is any pattern of inheritance in which traits do not segregate in accordance with Mendel's laws.
These laws describe the inheritance of traits linked to single genes on chromosomes in the nucleus. In Mendelian inheritance, each parent contributes one of two possible alleles for a trait. If the genotypes of both parents in a genetic cross are known, Mendel's laws can be used to determine the distribution of phenotypes expected for the population of offspring.
There are several situations in which the proportions of phenotypes observed in the progeny do not match the predicted values. Pleiotropy occurs when one gene influences two or more seemingly unrelated phenotypic traits.
Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function. Conservation genetics is an interdisciplinary subfield of population genetics that aims to understand the dynamics of genes in populations principally to avoid extinction. Therefore, it applies genetic methods to the conservation and restoration of biodiversity.
Researchers involved in conservation genetics come from a variety of fields including population genetics, molecular ecology, biology, evolutionary biology, and systematics. Genetic diversity is one of the three fundamental levels of biodiversity, so it is directly important in conservation.
Genetic variability influences both the health and long-term survival of populations because decreased genetic diversity has been associated with reduced fitness, such as high juvenile mortality, diminished population growth, reduced immunity, and ultimately, higher extinction risk. Haploinsufficiency in genetics describes a model of dominant gene action in diploid organisms, in which a single copy of the wild-type allele at a locus in heterozygous combination with a variant allele is insufficient to produce the wild-type phenotype.
Haploinsufficiency may arise from a de novo or inherited loss-of-function mutation in the variant allele, such that it produces little or no gene product. If the mutation calls for a color to be rolled, roll 1d6 and refer to the following: [1] Red , [2] Orange , [3] Yellow , [4] Green , [5] Blue , [6] Violet Neutral Mutations Advanced Aging: You advance in age by one age category.
Your life span is effectively shortened; your biological and chronological age effectively are advanced to the next stage of life.
If you are already venerable in age, you simply gain the benefits of becoming venerable again. You become genderless, converting your remaining organs into a cloaca to fulfill your other biological needs.
Agility: You feel your body shudder as you become more nimble. However, you take a -2 penalty to your Constitution score as your body thins out and accommodates your newfound flexibility. Albinism: Your skin drains of all pigment, and your eyes become a bloody red. Anxiety Disorder: While primed for combat, you are just as easily spooked when it starts. Aquatic Adaptation: You sprout gills and webbed digits. You gain the amphibious template. Aura of Flies: You secrete a chemical that seems to attract flies, causing them to swarm around you, constantly buzzing in your ears tirelessly.
This bestows a -4 penalty to Listen, Move silently, and Hide checks. Autism Disorder: You develop the neurodevelopmental disorder Autism. The effects of the disorder vary depending on the severity of your disorder. Roll 1d6 to determine where you fall on the spectrum: Low Functioning: You take a -4 penalty to your beauty score, and a -4 penalty to all social checks.
Bioluminescence: Part of your body generates a cold, softly glowing light. Roll to determine the color of the bioluminescence, and roll 1d6 to determine the conditions required to trigger the glow. At will.
However, if you are subject to a critical hit you rage unwillingly. If you are unable to rage, then you automatically become fatigued instead. If you already have a Rage or similar ability, you instead gain an additional daily usage from it.
Brain or Brawn? Bulbous Nose: Your nose swells to be large, red, and bulbous. Creatures who can see you cannot take you seriously, bestowing a -2 penalty to Diplomacy and Intimidate checks.
Bulging Eyes: Your eyes become exceptionally bulbous, conferring no bonuses or penalties.. Burrower: Your hands warp and sharpen to become more shovel-like.
You lose no functionality with your hands but you do gain a burrow speed of 10ft in soft earth, and leave a trail large enough for 3 creatures of your size to follow closely behind. However, the bright light of the surface world is too much for you to handle. You gain Light Sensitivity. Carnivorous: You become a true carnivore, subsisting solely on animal tissue for your diet.
This can include fish and insects. You gain little or no sustenance from devouring plant matter. Chitin: A chitinous membrane forms over your skin. The chitin is rather inflexible, however, bestowing a -2 penalty to your Dexterity score. Cold Blooded: You can't stand the cold; freezing takes half as long and in cold environments you become Slowed. However, hot environments do not bother you.
In hot environments, you become Hasted. Complex Mouthparts: You gain additional complex parts around your mouth, much like an arthropod. This can include external chelicerae, mandibles, maxillae, a proboscis, a radula, or other parts. Crystalline Body: Your body begins to shine in the light as take on the texture of glass. You no longer feel hungry, tired, and no longer need to breathe. Your type changes to Construct and you gain the Living Construct subtype. Cyclopian: Your eyes merge into one large eye.
You take a -2 penalty to ranged attack rolls, but your larger eye allows you to see better in the dark. You gain Low-Light vision; if you already have low-light vision from another source then the range doubles instead.
De-Aging: You de-age by one age category physically. Your life span does not change; your biological and chronological age effectively are rolled back to the previous stage of life.
You reverse all the benefits and detriments of having advanced in age category. If you are an adult who de-ages, you become a child. If you are a child, you return to a fetal state that dies in one minute if not preserved.
Death Rattle: Your body becomes rigged to explode when you die, dealing 2d6 explosive and acid damage per level in a 20 ft. Diurnal: You become active during the day and dormant during the night. Divisive Reproduction: Your reproductive organs wither and fall from your body.
Your reproductive system changes so that you may reproduce asexually. By cultivating enough mass reach maximum weight score, eating more than you need to , you increase in size category by one stage. You do not control your new spawn, but it is generally friendly towards you. You are unable to speak unless it is in rhyme. Dormant Blight: Your body begins to release debilitating chemicals while you sleep. Whenever you rest for more than 4 hours, plants around you wither and shrivel in a ft radius.
This effect is similar to that of the Diminish Plant prune growth spell. When possible, you leave a trail of dry, dead plants in your wake. Dromedary Hump: You gain a camel-like hump that impedes your ability to wear armor, but allows you to store food and water in it for days at a time.
If you overeat for a full week, you can store the nutrients for up to 1 day per point of Constitution. Armor must be specially made to adjust your hump, and even then you take a -1 penalty to your AC and the armor check penalty increases by Dwarfism: You shrink down to half the size of a creature typical of your race. Your height is halved and your weight is quartered as your size category is lowered by one to a minimum of Tiny.
Ear Holes: Your ears become simple ear holes. This does not impede their functionality. Egghead: Your head takes on a distinctly egg shape, and your muscles seem to atrophy. Eidetic Memory: You can remember everything that has happened to you, and you can recall episodes and events from memory in complete form.
This includes both good and bad memories. Eyestalks: Your eyes extend from your sockets on stalks. Any lost eyes will be regrown as new in 1d10 days. Fast Metabolism: You must eat twice as much of what you would normally eat, but you heal twice as fast when resting including hitpoint regeneration and ability score recovery , fast healing or regeneration effects are either doubled or last twice as long when applicable , and your weight score decreases by 1 every month you do not carefully monitor your diet.
Fivehead: your hairline recedes and your head elongates slightly, making your forehead appear much larger than before. Flippers: Your feet mutate into duck-like paddle feet. Force or Finesse? Foul Odor: You grow additional glands just under the skin that secrete an oily musk-like chemical. You gain the Stench ability, as a Troglodyte. Fruit: You produce a biological product in a form that can be safely harvested. Once plucked, a fruit lasts for 1d4 days before it loses its potency.
You may roll 1d10 to determine what type of fruit grows on a daily basis: Anti-radiation medication. Immune system booster. Mental booster. Poison antidote.
Sedative or tranquilizer. Tasty food. Toxic poison. Two properties or other effects. Gastrodontus: Your stomach folds, ripples, and tears as you gain a gnarly maw on your stomach. You can consume and speak through it just as well as with your normal mouth. Genderswapped: Your body changes before your very eyes, changing into that of the opposite sex.
Genetic Cesspool : Your aberrant genetic structure mimics features from other races. You gain a beneficial feature, detrimental feature, and neutral feature from different races. The exact features are to be determined by the DM. Genetic Normality: The genes that determine your ability scores blend together before separating.
Add your ability scores together and average them out, rounding up to determine your new ability scores. Genetic Soup: You feel your body shudder as your form ripples and quakes. You become a sentient slime person. You gain the gelatinous template from the savage species book Page with one exception; your mind retains its intellect, instead of dropping to 1.
Genomorph: You can alter your biological makeup to change your sex at will. You may choose to be biologically female, male, hermaphroditic, or agendered.
Changing sexes is a standard action. If you become pregnant as a biological female you are unable to change into a biological male or agendered form until you either give birth or otherwise terminate the pregnancy. Gigantism: You grow to double the size of a creature typical of your race. Your height is doubled and your weight is quadrupled as your size category is increased by one to a maximum of colossal. Green Father: Your body begins to release enriching nutrients while you sleep. Whenever you rest for more than 4 hours, plants around you begin to grow wildly in a ft radius.
This effect is similar to that of the Plant Growth overgrowth spell. When possible, a trail of flowers grows in your footsteps. Hairless: Your skin becomes uncomfortably smooth as every single hair falls out of your pores. You become completely hairless. Hairy: Your skin becomes nearly completely covered in body hair, taking on an almost sasquatch look.
Your hair grows at twice the rate and thickness, and any current hair you have doubles in length and volume. Hammerhead: Your head shifts and contorts into the shape of a hammerhead shark.
You can shake your head as a swift action to detect electrical fields in living creatures. However, because of the positioning of your eyes you take a -2 penalty to Spot checks. However, you feel impending doom at all times, and are shaken during combat encounters. Hemihypertrophy: One side of your body is significantly larger than the other, resulting in an unattractive lack of symmetry. Limbs on one side are longer and stronger than those on the other side, and facial features are distorted.
Double handed weapons do not gain the bonus of the reach, but gain half the bonus to damage.
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