Rivers Biology Chpt 9 Genetics
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50 terms
Terms | Definitions |
|---|---|
 Gregor Mendel | Austrian Monk who grew garden peas and studdied their genetics; came up with many genetic laws |
| True-Breeding | individuals in which offspring produced in self fertilization are identical to the parents |
| Self-fertilization | When the sperm and egg cells of a zygote come from the same original parent |
| Gene | hereditary information consisting of a sequence of nucleotides; they determine an individual's phenotype |
| Allele | the alternative forms of a gene |
| Gene Locus (Loci) | specific locations of genes on a chromosome |
| Dominance | when two alleles in a pair, this is the one that ultimately determines the characteristic of the individual |
| Recessive | When the two alleles in a pair differ, this is the one that is not shown in the individual's characteristics |
| Genotype | an individual's genetic makeup |
| Phenotype | the physical traits of an individual |
| cross-fertilization | the fertilization of one plant by the gamete of another plant (aka a genetic cross) |
| Hybrid | the offspring of 2 different true-breeding varieties |
| P Generation | the first cross in a sequence of crossing 2 true-breeding plants (this is the cross of the 2 true-breeding plants themselves); the "parental" generation |
| genetic cross | cross-fertilization (between 2 parents) |
| F1 Generation | the hybrid offspring of the P generation |
| F2 Generation | the offspring of F1 generation plants |
| Gametes | egg and sperm cells (haploid) |
| Punnett Square | a chart which shows the offspring of 2 parents based on their genotypes |
| Monohybrid cross | the parents of the cross differ in only one characteristic |
| Dihybrid cross | the parents of the cross differ in 2 characteristics |
| Multiple alleles | the idea that there are many alternate forms of genes and traits (idea of Mendel) |
| Meiosis | the creation of gametes from diploid individuals |
| Homozygous | when a gene has 2 of the same allele, an individual is this for that trait |
| Heterozygous | when an organism has 2 different alleles for a certain gene |
| Law of Segregation | Mendel's idea that we get one allele for each trait from our father, and one from our mother |
| Law of Independant assortment | Mendel's idea that each pair of alleles sorts independantly of the other pairs during gamete formation |
| Test Cross | the mating of an individual a known phenotype, but unknown genotype with a homozygous recessive individual to find the unknown genotype |
| Rule of Multiplication | the rule that the probability of 2 events happening together is the same as the product of their individual probabilities |
| Wild-Type traits | those traits seen most often in nature |
| Pedigree | family tree; genetic ancestory |
| Carrier | an individual with one allele for a recessive dissorder, but does therefore not display the disorder (but can pass the allele on to the next generation) |
| Autosomal Recessive disorder | examples are cystic fiberosis, a certain type of deafness, Albinism, Galactosemia, Phenylketonuria, Sickle-Cell disease, and Tay Sachs disease |
| Cystic Fiberosis | autosomal recessive disorder in which there is excessive mucus in the lungs, liver, and digestive tract;causes susceptability to infection |
| Tay Sachs Disease | autoaomal recessive disorder in which the individual has lipid accumulation in brain cells causing early death, mental defficiency, and blindness |
| Dominant Disorder | examples are Achondroplasia, Alzheimer's, and Huntington's |
| Achondroplasia | autosomal dominant disorder; dwarfism |
| Huntington's disease | autosomal dominant disorder; mental deterioration and uncontrollable movements; strikes in middle age, so often goes undetected for a long time and is passed on to the next generation |
| Incomplete dominance | the trait caused by a heterozygous individual is somewhere between that caused by a homozygous dominant and a homozygous recessive individual (EX: Hypercholesterolemia ) |
| Hypercholesterolemia | an incomplete dominance, recessive disorder; causes extremely high levels of cholesterol in the blood because of a lack of receptors on cells that "clean up" cholesterol |
| Codominance | In a heterozygous individual, both the dominant and recessive traits show through equally (example bloodtype) |
| Bloodtype | is determined by the type of carbohydrate that is found on one's red blood cells; shows codominance (can be A, B, O or AB) |
| Pleiotropy | the impact of a single gene on more than one trait (EX: Sickle cell disease) |
| Sickle cell disease | an example of pleiotropy and a recessive disorder; causes abnormal hemoglobin molecules that do not carry oxygen efficiently and abnormally shaped red blood cells (also connected to malaria in a special way) |
| inbreeding | mating of close relatives; increases the chances of having a child homozygous for a harmful trait |
| Polygenic Inheritence | When many genes affect one trait (EX: skin color) |
| Chromosomal Theory of inheritance | the idea that genes are located at specific locations oon chromosomes and the behavior of chromosomesduring meiosis & fertilization accounts for inheritance patterns |
| Linked genes | genes that tent to be inherited together as a set (EX: grey body & long wings of a fly and black body & short wings |
| recombinant frequency | the percentage of recombinant (different from the parental genotype) offspring among the total |
| Sex-Linked gene | any gene located on a sex chromosome (has affect of traits of offspring depending on male/female or X/Y); EX: red-green color blindness & Duchenne muscular distrophy |
| Duchenne muscular distrophy | sex-linked dissorder; causes progressive weakening & loss of muscle tissue (was prevolent in the royal families of Europe) |
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