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| 2350174420 | The Chromosome Theory of Inheritance | All genes have specific loci along chromosomes, and these chromosomes are what undergo segregation and independent assortment; a specific gene is carried on a specific chromosome | 0 | |
| 2350174421 | Wild Type | The phenotype for a character most commonly observed in natural populations (e.g. for fruit flies, red eyes is the wild type, represented by w+) | 1 | |
| 2365147240 | Mutant Type | The phenotypes that are alternative to the wild type (e.g. for fruit flies, white eyes is a mutant type, represented by w) | 2 | |
| 2365157923 | Thomas Hunt Morgan | An experimental embryologist at Columbia University who bred fruit flies over many generations to research the placement of genes on chromosomes | 3 | |
| 2365161518 | Morgan's Fruit Fly Experiment | -Mated male mutants with female wild types -F1 generation all had red eyes (wild type) -F2 generation was 3:1 red:white, but only males had the white eyes -Showed that the mutant white eye allele is only located on the x chromosome, so only males had it because they would have one recessive white eye allele on their x chromosome and none on their y chromosome -Females couldn't have white eyes because they would have to homozygous recessive, but there were only red-eyed fathers in the F1 generation -Supports the chromosome theory of inheritance | 4 | |
| 2367736583 | Sex-Linked Gene | A gene that is located on either sex chromosome; those on the Y chromosome are called Y-linked genes, those located on the X chromosome are called X-linked genes | 5 | |
| 2367753227 | How is sex determined in an organism? | -All eggs in a female have one X chromosome -Half of the sperm in a male have one X chromosome, while the other half have one Y -50/50 chance, because half the time a Y sperm combines with an egg to get an XY male and half the time an X sperm combines with an egg to get an XX female | 6 | |
| 2367766605 | SRY Gene | "Sex-determining region of Y"; a gene on the Y chromosome that is required for the development of testes, so without this gene, the gonads of an embryo develop into ovaries | 7 | |
| 2367774762 | Y-Linked Genes | The Y chromosome is passed on basically intact from father to son, but there are very few Y-linked genes so not many disorders are transferred from the Y chromosome | 8 | |
| 2367785820 | X-Linked Genes | -Human X chromosome has over 1,000 genes -Fathers can only pass x-linked alleles to their daughters, but mothers can pass them to both sons and daughters, so most disorders are inherited from the mother -X-linked recessive traits can only be expressed in females if both of the mother's X chromosomes have it (homozygous recessive) | 9 | |
| 2367809901 | Hemizygous | A term used to describe male sex chromosomes; because very few X-linked genes have a Y-linked counterpart, males only need one recessive X-linked allele from the mother to express that trait in their phenotype; this is why X-linked recessive disorders are much more common in males than females | 10 | |
| 2367834064 | Color-Blindedness | An X-linked recessive disorder that, like all X-linked recessive disorders, is much more common in males than females | 11 | |
| 2367836775 | Duchenne Muscular Dystrophy | An X-linked recessive disorder that causes a progressive weakening of the muscle and loss of coordination; affected individuals rarely live past their early 20s | 12 | |
| 2367841139 | Hemophilia | An X-linked recessive disorder that causes the absence of one or more of the proteins needed for blood clotting; when an afflicted person is injured, the bleeding is prolonged because the clot forms too slowly, which can lead to pain | 13 | |
| 2367851319 | X-Chromosome Inactivation | Because females have twice as many X-linked genes as males, one of them must be inactivated so that the genes will only code for half as many proteins to be made; females with heterozygous X-linked genes will have half of their cells expressing the gene from the father and half expressing the gene from the mother | 14 | |
| 2367857095 | Barr body | The inactive, condensed X chromosome in a female that lies along the inside of the nuclear envelope; the genes in the Barr body X chromosome are not expressed; one of the two X chromosomes in a female is randomly inactivated during early embryonic development | 15 | |
| 2367880477 | How does an X-chromosome become a Barr body? | -There is a special region on every X chromosome that contains several genes involved in the inactivation process -During early embryonic development, the two regions from each X chromosome associate briefly -DNA and histone proteins are modified by the attachment of a methyl group (-CH3) to one of the nitrogenous bases of the DNA nucleotides -The XIST gene then becomes active only on the chromosome that will become the Barr body | 16 | |
| 2367893470 | XIST Gene | "X-inactive specific transcript"; the gene that is active on the X chromosome that will eventually become the Barr body because multiple copies of the protein that it codes for attach to the future Barr body and almost cover it; interaction of these proteins with the chromosome initiate the X inactivation | 17 | |
| 2367902078 | Linked Genes | Two or more genes on the same chromosome that tend to be inherited together; the presence of linked chromosomes decreases variation because these traits tend to be inherited together in the parental combination, so the offspring usually resemble the parental phenotypes | 18 | |
| 2367919346 | Parental Types | Phenotypes that resemble the parents (e.g. the parental types of fruit flies are gray body/normal wings and black body/vestigial wings) | 19 | |
| 2367923899 | Recombinant Types | Phenotypes that do not resemble the parents (e.g. the recombinant types of fruit flies are gray body/vestigial wings and black body/normal wings) | 20 | |
| 2367928974 | Genetic Recombination | The production of recombinant type offspring; when 50% of all offspring are recombinant types, then there is a 50% frequency of recombination; genes that are at loci farther away from each other are more likely to cross over so therefore have higher recombination frequencies | 21 | |
| 2367962078 | Crossing Over | The process that physically breaks apart linked genes and recombines them to different chromosomes; replicated homogenous chromosomes are paired during prophase of meiosis I, and the corresponding segments of one maternal and one paternal chromatid and exchanged, so the end portions of two nonsister chromatids trade places and the once-linkde genes are split up | 22 | |
| 2367981876 | Chapter Summary: what processes increase variation in species? | 1. Sexual reproduction (two parents) 2. Random mating--more traits for gene pool 3. Meiosis--random assortment in metaphase I and crossing over recombines genes into different types 4. Mutation | 23 | |
| 2367985840 | Chapter Summary: what processes decrease variation in species? | 1. Asexual reproduction (one parent) 2. Nonrandom mating--same traits available for gene pool 3. Linked genes--same traits in offspring | 24 | |
| 2367989337 | Genetic Map | An ordered list of the genetic loci along a particular chromosome; the farther apart two genes are on a chromosome, the more likely that crossover will occur and there will be a higher recombination frequency | 25 | |
| 2367999888 | Linkage Map | A genetic map of chromosomes based on recombination frequencies | 26 | |
| 2368007112 | Map Units | Used to express distance between genes in a linkage map; one map unit is equal to a 1% recombination frequency | 27 | |
| 2368012029 | Genetically Unlinked Genes | Though they are physically linked on the same chromosome, they are not genetically linked because they have the maximum recombination frequency (50%), which is the same as that of two genes on different chromosomes | 28 | |
| 2368018398 | Cytogenetic Map | Maps of chromosomes that locate genes with respect to chromosomal features, such as stained bands, that can be seen in the microscope; these are different from linkage maps because they express the physical distance between genes, rather than the difference in recombination frequencies | 29 | |
| 2368026099 | Nondisjunction | An error in meiosis that causes one daughter gamete to have two of the same chromosome and one to not have that chromosome at all (aneuploidy); occurs either in meiosis I when the pair of homologous chromosomes do not separate properly or in meiosis II when the sister chromatids fail to separate; more common in the eggs of elder women | 30 | |
| 2373624876 | Aneuploidy | When a zygote has an abnormal number of a particular chromosome because it was created by the fertilization of a normal gamete with one that has gone through nondisjunction; large-scale chromosomal number alterations can lead to developmental disorders or miscarriage | 31 | |
| 2373632834 | Monosomy | When a zygote is aneuploid by having 2n-1 chromosomes, because it involved the fertilization of a normal gamete with one that was missing a chromosome; this usually results in miscarriage | 32 | |
| 2373638509 | Trisomy | When a zygote is aneuploid by having 2n+1 chromosomes, as a result of either nondisjunction (normal gamete + gamete with extra chromosome) or translocation; trisomy is the cause of Down syndrome along with other disorders | 33 | |
| 2373647792 | Polyploidy | When an organism has more than two complete chromosome sets in all of its somatic cells; this is true for many plants and has been key in the evolution of plants including bananas (3n), wheat (6n), and strawberries (8n) | 34 | |
| 2373660611 | Triploidy | When an organism has three complete chromosome sets in all of its somatic cells (3n); could result by the fertilization of an abnormal diploid gamete (2n because all of its chromosomes underwent nondisjunction) | 35 | |
| 2373661648 | Tetraploidy | When an organism has four complete chromosome sets in all of its somatic cells (4n) | 36 | |
| 2373683355 | What are the four possible chromosomal mutations? | 1. Deletion 2. Duplication 3. Inversion 4. Translocation All of the above are caused by either errors in meiosis (usually during synapsis) or damage from agents such as radiation that leads to chromosomal breakage | 37 | |
| 2373684970 | Deletion | A lethal chromosomal mutation that occurs when a fragment of a chromosome is lost, so this chromosome is missing several genes |  | 38 |
| 2373692656 | Duplication | A harmful chromosomal mutation that occurs when an extra chromosome fragment broken off from deletion attaches itself to a sister/homologous nonsister chromatid, so there are now two identical copies of certain genes in that chromosome |  | 39 |
| 2373699527 | Inversion | A phenotype-altering chromosomal mutation that occurs when an extra chromosome fragment broken off from deletion reattaches itself to that chromosome but in reverse orientation |  | 40 |
| 2373703812 | Translocation | A harmful (or phenotype-altering) chromosomal mutation that occurs when an extra chromosome fragment broken off from deletion attaches itself to a nonsister, nonhomologous chromatid |  | 41 |
| 2373719949 | How do deletions and duplications occur during synapsis/meiosis? | When the different chromatids are crossed, they often exchange unequal lengths of gene fragments, so one has deletion and one has duplication for those certain genes | 42 | |
| 2373728088 | Syndrome | A specific set of traits characteristic of the type of aneuploidy that a cell has | 43 | |
| 2373730514 | Down Syndrome | AKA trisomy 21; a type of aneuploid disorder in which there is an extra chromosome 21, so each somatic cell has a total of 47, rather than 46, chromosomes | 44 | |
| 2373747037 | Klinefelter Syndrome | A disorder in males in which there is an extra X chromosome (XXY); those affected are usually sterile and can show signs of female body characteristics | 45 | |
| 2373757512 | Turner Syndrome | AKA monosomy X; a disorder in females in which there is only only X chromosome (X0); those affected are still phenotypically female yet they are sterile because their sex organs do not mature | 46 | |
| 2373768868 | Cri Du Chat Syndrome | "Cry of the cat"; a disorder resulting from a specific deletion in chromosome 5; those affected are intellectually disabled, have a small head, and usually die in infancy or early childhood | 47 | |
| 2373774380 | Chronic Myelogenous Leukemia (CML) | A certain strain of bone marrow cancer that results from a translocation in white blood cells, which activates a genes that leads to uncontrolled cell cycle progression | 48 | |
| 2373778802 | Philadelphia Chromosome | A shortened version of chromosome 22 because a large fragment of it was translocated with a small fragment of chromosome 9, causing CML | 49 |
