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Turner Syndrome
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Chromosome disorder in females. a x chromosome is missing or part of one x is deleted. short stature and webbed neck.
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Thomas Hunt Morgan
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Dicovered that sometimes alleles for different traits do not assort independently and can be linked because they exist on the same chromosome. Discovered that sex-linked traits appear in different rates in males and in females because males need only one recessive allele to express the recessive trait.
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Monosomic
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A chromosomal condition in which a particular cell has only one copy of a chromosome, instead of the normal two; the cell is said to be ________ for that chromosome.
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Chromosome Theory of Inheritance
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A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.
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Cytogenetic Maps
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a chart of a chromosome that locates genes with respect to chromosomal features distinguishable in a microscope, by comparing this with a linkage map we can determine that the linear order is the same but the spacing between genes is not.
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Law of independent assortment
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Mendel's second law, stating that each allele pair segregates independently during gamete formation; applies when genes for two characteristics are located on different pairs of homologous chromosomes.
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Imprinting
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the process by which certain animals form attachments during a critical period very early in life
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Inversion
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An aberration in chromosome structure resulting from reattachment in a reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated.
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Miscarriage
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The spontaneous expulsion of a baby from the mother's body before week 20 of pregnancy
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Aneuploidy
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A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
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Down Syndrome
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A human genetic disease caused by presence of an extra chromosome 21; characterized by mental retardation and heart and respiratory defects. Often called Trisomy 21
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Translocation
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change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome
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Linked Genes
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genes located on the same chromosome that tend to be inherited together in genetic crosses, when following these genes they will deviate from the law of independent assortment
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X 0 System
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how gender is determined in grasshoppers and cockroaches, male has one X and a female has two X's
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Males
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Because _____ have only one locus, the term homozygous is useless(hemizygous) instead , any ____ receiving a recessive sex linked gene from the mother will inherit it.
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Hemizygous
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in a diploid organism, having only one allele for a given trait, typically the case for X-linked genes in male mammals and Z-linked genes in female birds
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Z W System
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birds, some fishes and insects; sex determined by eggs, female has ZW and male has ZZ (ex. rooster)
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Klinefelter Syndrome
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syndrome in males that is characterized by small testes and long legs and enlarged breasts and reduced sperm production and mental retardation
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Mary Lyon
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who suggests that early in the development of normal females one of the X chromosomes is inactivated in every somatic cell; random as to which is expressed: in some cell the material chromosome is expressed; in other cells the male chromosome is expressed (Females consist of a mosiac of two types of cells.
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Phenotype
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The physical traits that appear in an individual as a result of its gentic make up.
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Cytology
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the science which deals with the formation, structure, and function of cells
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Duplication
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An aberration in chromosome structure resulting from an error in meiosis or mutagens; duplication of a portion of a chromosome resulting from fusion with a fragment from a homologous chromosome.
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Crossing Over
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the exchange of genetic material between homologous chromosomes during meiosis; can result in genetic recombination
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Recombination Frequency
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percentage of recombinants, meaning percentage of of offspring that had traits from crossover. recombination frequencies are lower when alleles are closer together.
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Trisomic
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A chromosomal condition in which a particular cell has an extra copy of one chromosome, instead of the normal two; the cell is said to be _______ for that chromosome.
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Linkage Map
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A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes. The greater the frequency of recombination between two genetic markers, the farther apart they are assumed to be. See also genetic map.
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Hemophilia
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A human genetic disease caused by a sex-linked recessive allele; characterized by excessive bleeding following injury due to an absence of the essential proteins allowed for clot formation, treated with intravenous injections of the protein.
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CML
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What leukemia is characterized by Philadelphia chromosomal translocation (9;22); massive splenomegaly; peripheral leukocytosis (commonly > 100, 00); decreased LAP levels; and nonspecific symptoms of fatigue, malaise, weight loss, and anorexia?
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Extranuclear Genes
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Genes that are found in organlles in the cytoplasm; mitcohondria, chrlorplasts. Inherited maternally
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Map Units
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A measurement of the distance between genes; one map unit is equivalent to a 1 percent recombination frequency. Can be a maximun vaalue of 50%
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Barr Body
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A dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome, reactivated in the cells that give rise to the ova.
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Genetic Map
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an ordered list of genetic loci (genes or other genetic markers) along a chromosome
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Parental Types
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Offspring with a phenotype that matches one of the parental phenotypes.
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Genomic Imprinting
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a phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent
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Genotype
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the particular alleles at specified loci present in an organism
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Deletion
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(1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene.
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Sex linked Gene
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any gene that is located on a sex chromosome
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Haplo- Diploid system
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There are no sex chromosomes in most species of bees and ants. Females develop from fertilized eggs (diploid) and males develop from unfertilized eggs (haploid). No fathers
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SRY
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The gene on the Y chromosome whose product instructs the undifferentiated fetal gonads to develop into testes
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Philadelphia Chromosome
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a shortened chromosome produced when a large portion of chromosome 22 is exchanged with a small fragment from a tip of chromosome 9
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Anaphase 1
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The third phase of Meiosis where homologus pairs seperate and move to opposite poles
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Nondisjunction
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error in meiosis in which homologous chromosomes don't separate; gametes end up with wrong number of chromosomes
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XIST
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X is inactive in specific transcript. Transcribed only from the inactive X. It is located in teh XIC. RNa is 17kb lond, but never leaves the nucleaus and does not code for a protein. Non-coding RNa, that coats the inactive X. Required for X activation.
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IGF2
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one of the first imprinted genes to be identified. found in mice. encodes a growth hormone called insulin-like growth factor 2 that is needed for proper growth. lack of it results in dwarf.
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Polyploidy
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A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
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Recombinant Types
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Offspring who have inherited new combinations of genes and have phenotypes that don't match either parental phenotypes (usually 50%)
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Clot Formation
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Happens when cut tissue release thromboplastin-interacts with factor VII
prothrombin--> thrombin
fibrinogen--(thrombin)--> fibrin
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Mutant Phenotypes
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traits that are alternatives to the wild type are called ________ _____ because they are due to alleles assumed to have originated as changes (mutations) of the wild-type allele
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Mitochondrial Myopathy
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muscle weakeness, death of muscle cells, dysphagia, speech difficulties, affects muscles of eye
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Wild Type
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An individual with the phenotype most commonly observed in natural populations; also refers to the phenotype itself. +
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Alfred Sturtevant
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Constructed a gene map of the fruit fly using crossing over frequencies.
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Trisomy 21
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condition in which an individual has three number 21 chromosomes, resulting in Down syndrome
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Methylation
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process that plays a role in the control of genetic expression, initiation of DNA Replication, Protection against Viral infection, and Repair of DNA
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Syndrome
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a group of symptoms or signs that collectively characterize or indicate a disease, disorder, abnormality, etc.
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Genetic Recombination
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new combination of genetic information in a gamete as a result of crossing over during prophase I of meiosis
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