GN 311 terms 1

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GN 311 terms 1
2010-09-08 13:29:19
Genetics test

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  1. Addition rule
    the probability of any 2 or more mutually exclusive events occurring is calculated by adding the probabilities of the individual events
  2. Allele
    one of 2 or more alternate forms of a gene
  3. Amniocentesis
    Procedure used for prenatal genetic testing to obtain a sample of amniotic fluid from a pregnant woman. A long sterile needle is inserted through the abdominal wall into the amniotic sac to obtain the fluid
  4. Anaphase
    stage of mitosis in which chromatids separate and move chromosomes the spindle poles
  5. Anaphase I
    stage of meiosis I. In anaphase II, chromatids separate and move toward the spindle poles
  6. Anaphase II
    stage of meiosis II. In anaphase II, chromatids separate and move toward the spindle poles
  7. Anticipation
    increasing severity or earlier age of onset of a genetic trait in succeeding generations. For example, symptoms of a genetic disease may become more sever as the trait is passed from generation to generation
  8. Archaea
    one of the 3 primary divisions of life. It consists of unicellular organisms with prokaryotic cells
  9. Autosome
    Chromosome that is the same in males and females; nonsex chromosome
  10. Backcross
    Cross between an F1 individual and one of the parental (P) genotypes
  11. Barr body
    Condensed, darkly staining structure that is found in most cells of female placental mammals and is an inactivated X chromosome
  12. Bivalent
    Refers to a synapsed pair of homologous chromosomes
  13. Blending inheritance
    Early concept of heredity proposing that offspring possess a mixture of the traits from both parents
  14. Cell cycle
    Stages through which a cell passes from one cell division to the next
  15. Cell theory
    All life is composed of cells, that cells arise only from other cells, and the cell is the fundamental unit of structure and function in living organisms
  16. centiMorgan
    Another name for map unit
  17. Checkpoint
    A key transition point at which progression to the next stage in the cell cycle is regulated
  18. Chromatin
    Material found in the eukaryotic nucleus; consists of DNA and proteins
  19. Chromosome theory of heredity
    States that genes are located on the chromosome
  20. Codominance
    Type of allelic interaction in which the heterozygote simultaneously expresses traits of both homozygotes
  21. Coefficient of coincidence
    Ratio of observed DCO to expected DCOs
  22. Cohesin
    Molecule that holds the 2 sister chromatids of a chromosome together. The breakdown of it at the centromeres enables the chromatids to separate in anaphase of mitosis and anaphase II of meiosis
  23. Complementation
    2 different mutations in the heterozygous condition are exhibited as the wild-type phenotype; indicates that the mutations are at different loci
  24. Complementation test
    Test designed to determine whether 2 diff mutations are at the same locus (allelic) or at diff loci (nonallelic). 2 individuals that are homozygous for the 2 independently derived mutations are crossed, producing F1 progeny that are heterozygous for the mutations. If the mutations are at the same locus, the F1 will have a mutant phenotype. If the mutations are at diff loci, the F1 will have a wild-type phenotype
  25. Concept of dominance
    Principle of heredity discovered by Mendel stating that, when 2 diff alleles are present in a genotype, only 1 allele may be expressed in the phenotype. The dominant allele is the allele that is expressed, and the recessive allele is not.
  26. Concordance
    % of twin pairs in which both twins have a particular trait
  27. Consanguinity
    Mating btw related individuals (double line)
  28. Continuous characteristic
    Displays a large # of possible phenotypes that are not easily distinguished (height)
  29. Coupling (cis) configuration
    Arrangement in which 2 or more wild-type genes are on 1 chromosome and their mutant alleles are on the homologous chromosome
  30. Crossing over
    Exchange of genetic material btw homologous but nonsister chromatids
  31. Cytokinesis
    Process by which the cytoplasm of a cell divides
  32. Cytoplasmic inheritance
    Inheritance of characteristics encoded by genes located in the cytoplasm. B/c the cytoplasm is usually contributed entirely by only 1 parent, most cytoplasmically inherited characteristics are inherited from a single parent
  33. Dihybrid cross
    A cross btw 2 individuals that differ in 2 characteristics--more specifically, a cross btw individuals that are homo for diff alleles at the 2 loci (AABBxaabb); also refers to cross btw hetero at 2 loci (AaBbxAaBb)
  34. Dioecious organism
    Belongs to a species whose members have either male or female reproductive structures
  35. Diploid
    Processing 2 sets of chromosomes (2 genomes)
  36. Discontinuous characteristic
    Exhibits only a few, easily distinguished phenotypes. Ex. a seed shape in which seeds are either round or wrinkled
  37. Dizygotic twins
    Nonidentical twins that arise when 2 diff eggs are fertilized by 2 diff sperm (fraternal twins)
  38. Dominant
    Refers to an allele or a phenotype that is expressed in homo (AA) and in hetero (Aa)
  39. Dosage compensation
    Equalization in males and females of the amt of protein produced by X-linked genes. In placental mammals, it is accomplished by the random inactivation of 1 X chromosome in the cells of females
  40. Epigenetics
    Phenomena due to alterations to DNA that do not include changes in the base sequence; often affect the way in which the DNA sequences are expressed. Such alterations are often stable and heritable in the sense that they are passed from one cell to another
  41. Epistasis
    Type of gene interaction in which a gene at one locus masks or suppresses the effects of a gene at a diff locus
  42. Epistatic gene
    Masks or suppresses the effect of a gene at a diff locus
  43. Eubacteria
    1 of the 2 primary divisions of life. It consists of unicellular organisms w/ prokaryotic cells and include most of the common bacteria
  44. Eukaryote
    Organism w/ a complex cell structure including a nuclear envelope and membrane-bounded organelles. 1 of the 3 primary divisions of life, they include unicellular and multicellular forms
  45. Expressivity
    Degree to which a trait is expressed
  46. F1 (filial 1) generation
    Offspring of the initial parents (P) in a genetic cross
  47. F2 (filial 2) generation
    Offspring of the F1 generation in a genetic cross; the 3rd generation of a genetic cross
  48. Fertilization
    Fusion of gametes, or sex cells, to form a zygote
  49. Gene
    Genetic factor that helps determine a trait; often defined at the molecular level as a DNA sequence that is transcribed into an RNA molecule
  50. Gene interaction
    Interactions btw genes at diff loci that affect the same characteristic
  51. Genetic counseling
    Educational process that attempts to help patients and family members deal w/ all aspects of a genetic condition
  52. Genetic map
    Map of the relative distances btw genetic loci, markers, or other chromosome regions determined by rates of recombination; measured in % recombination or map units
  53. Genetic maternal effect
    Determines the phenotype of an offspring. an offspring inherits genes for the characteristics from both parents, but the offspring's phenotype is determined not by its own genotype but by the nuclear genotype of its mother
  54. Genic blance system
    Sex-determining system in which sexual phenotype is controlled by a balance btw genes on the X chromosome and genes on the autosomes
  55. Genic sex determination
    Sex determination in which the sexual phenotype is specified by genes at 1 or more loci, but there are no obvious diff in the chromosomes of males and females
  56. Genome
    Complete set of genetic instructions for an organism
  57. Genomic imprinting
    Differential expression of a gene that depends on the sex of the parent that transmitted the gene. If the gene is inherited from the father, its expression is diff from that if it is inherited from the mother
  58. Genotype
    The set of genes possessed by an individual organism
  59. Germ-plasm theory
    Cells in the reproductive organs carry a complete set of genetic info
  60. Goodness-of-fit chi-square test
    Statistical test used to evaluate how well a set of obs values fit the exp values. The probability associated w/ a calculated chi-square value is the probability that the diff btw the obs and exp values may be due to chance
  61. Haploid
    Possessing a single set of chromosomes (1 genome)
  62. Hemizygosity
    Possession of a single allele at a locus. Males of organisms w/ XX-XY sex determination are __ for X-linked loci, b/c their cells possess a single X chromosome
  63. Hermaphroditism
    Condition in which an individual organism possesses both male and female reproductive structures. True __ produce both male and female gametes
  64. Heterogametic sex
    The sex (male or female) that produces 2 types of gametes wrt sex chromosomes. Ex. in the XX-XY sex-determining system, the male produces both X-bearing and Y-bearing gametes
  65. Heterozygous
    An individual organism that possessed 2 diff alleles at a locus
  66. Histone
    Low-molecular-weight protein found in eukaryotes that complexes w/ DNA to form chromosomes
  67. Homogametic sex
    The sex (male or female) that produces gametes that are all alike w/ regard to sex chromosomes. Ex. in the XX-XY sex determining system, the female produces only X-bearing gametes
  68. Homologous pair
    2 chromosomes that are alike in structure and size and that carry genetic info for the same set of hereditary characteristics. 1 chromosome of it is inherited from the male and other from the female parent
  69. Homozygous
    An individual organism that possesses 2 identical alleles at a locus
  70. Hypostatic gene
    Gene that is masked or suppressed by the action of a gene at a diff locus
  71. Incomplete dominance
    the phenotype of a heterozygote that is intermediate btw the phenotypes of the 2 homos
  72. Incomplete penetrance
    Refers to a genotype that does not always express the expected phenotype. Some individuals possess the genotype for a trait but do not express the phenotype
  73. Inheritance of acquired characteristics
    Early notion of inheritance proposing that acquired traits are passed to descendents
  74. Interchromosomal recombination
    Recombination among genes on diff chromosomes
  75. Interference
    Degree to which 1 crossover interferes w/ additional crossovers
  76. Interkinesis
    Period between meiosis I and meiosis II
  77. Interphase
    Period in the cell cycle between the cell divisions. The cell grows, develops, and prepares for cell division
  78. Intrachromosomal recombination
    Recombination among genes located on the same chromosome
  79. Klinefelter syndrome
    Human condition in which cells contain 1 or more Y chromosomes along w/ multiple X chromosomes (most commonly XXY but may also be XXXY, XXXXY, or XXYY). They are male in appearance but freq possess small testes, some breast enlargement, and reduced facial and pubic hair; often taller than normal and sterile; normal intelligence
  80. Lethal allele
    Causes the death of an individual organism, often early in development, and so the organism does not appear in the progeny of a genetic cross. Recessive __ kill individual organisms that are homo for the allele; dominant __ kill both hetero and homo
  81. Linkage group
    Genes located together on the same chromosome
  82. Linked genes
    Genes located on the same chromosome
  83. Locus
    Position on a chromosome where a specific gene is locatec
  84. Lyon hypothesis
    In 1961, this proposes that 1 X chromosome in each female cell becomes inactivated (a Barr body) and suggests that which X becomes inactivated is random and varies from cell to cell
  85. M (mitotic) phase
    Period of active cell division; includes mitosis (nuclear division) and cytokinesis (cytoplasmic division)
  86. Map unit (m.u.)
    Unit of measure for distances on a genetic map; 1 __=1% recomb
  87. Mapping function
    Relates recombination frequencies to actual physical distances between genes
  88. Meiosis
    Process in which chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells. Consists of 2 divisions
  89. Metaphase
    Stage of mitosis where chromosome align in the center of the cell
  90. Metaphase I
    Stage of meiosis I where homo pairs of chromosomes align in the center of the cell
  91. Metaphase II
    Stage of meiosis II where individual chromosomes align on the metaphase plate
  92. Mitosis
    Process by which the nucleus of a eukaryotic cell divides
  93. Model genetic organism
    An organism that is widely used in genetic studies b/c it has characteristics, such as short generation time and large # of progeny, that make it well suited to genetic analysis
  94. Molecular genetics
    Study of the chemical nature of genetic info and how it is encoded, replicated, and expressed
  95. Monoecious organism
    Individual organism that has both male and female reproductive structures
  96. Monohybrid Cross
    A cross btw 2 individuals that differ in a single characteristic-homo for diff alleles at the same locus (AAxaa); or that are both hetero for 2 alleles at a single locus (AaxAa)
  97. Monozygotic twins
    Identical twins that arise when a single egg fertilized by a single sperm splits into 2 separate embryos
  98. Morgan
    100 map units
  99. Multifactorial characteristic
    Determined by multiple genes and environmental factors
  100. Multiple alleles
    Presence in a group of individuals of more than 2 alleles at a locus. Although, for the group, the locus has more than 2 alleles, each member of the group has only 2 of the possible alleles
  101. Multiplication rule
    States that the probability of 2 or more independent events occurring together is calculated by multiplying the probabilities of each of the individual events
  102. Nondisjunction
    Failure of homo chromosomes or sister chromatids to separate in meiosis or mitosis
  103. Nonrecombinant (parental) gamete
    Contains only the original combinations of genes present in the parents
  104. Nonrecombinant (parental) progeny
    Possesses the original combination of traits possessed by the parents
  105. Norm of reaction
    Range of phenotypes produced by a particular genotype in diff environmental conditions
  106. Nucleus
    Space in eukaryotic cells that is enclosed by the nuclear envelope and contains the chromosomes
  107. Oogenesis
    Egg production in animals
  108. Origin of replication
    Site where DNA synthesis is initiated
  109. P (parental) generation
    First set of parents in a genetic cross
  110. Pangenesis
    Early concept of heredity proposing that particles carry genetic info from diff parts of the body to the reproductive organs
  111. Pedigree
    Pictorial representation of a family history outlining the inheritance of 1 or more traits or diseases
  112. Penetrance
    % of individuals w/ a particular genotype that express the phenotype expected of that genotype
  113. Phenocopy
    Phenotype that is produced by environmental effects and is the same as the phenotype produced by a genotype
  114. Phenotype
    Appearance or manifestation of a characteristic
  115. Physical map
    Map of physical distances btw loci, genetic markers, or other chromosome segments; measured in base pairs
  116. Pleiotropy
    A single genotype influences multiple phenotypes
  117. Polygenic characteristic
    Encoded by genes at many loci
  118. Population genetics
    Study of the genetic composition of populations (groups of members of the same species) and how a population's collective group of genes changes w/ the passage of time
  119. Preformationism
    Early concept of inheritance proposing that a mini adult (homunculus) resides in either the egg or the sperm and increases in size during development, w/ all traits being inherited from the parent that contributes the homunculus
  120. Primary spermatocyte
    Spermatogonium that has entered prophase I
  121. Principle of independent assortment (Mendel's 2nd law)
    Important principle of heredity that states that genes encoding diff characteristics (genes at diff loci) separate independently; applies only to genes located on diff chromosomes or to genes far apart on the same chromosome
  122. Principle of segregation (Mendel's 1st law)
    Important principle of heredity that states that each diploid individual possesses 2 alleles at a locus and that these 2 alleles separate when gametes are formed, 1 allele going into each gamete
  123. Probability
    Likelihood of a particular event occurring; the # of times a particular event occurs/the # of all possible outcomes
  124. Proband
    A person w/ a trait or disease for whom a pedigree is constructed
  125. Prokaryote
    Unicellular organism w/ a simple cell structure. Include eubacteria and archaea
  126. Prometaphase
    Stage of mitosis where the nuclear membrane breaks down and the spindle microtubules attach to the chromosomes
  127. Prophase
    Stage of mitosis; chromosomes contract and become more visible, the cytoskeleton breaks down, and the mitotic spindle begins to form
  128. Prophase I
    Stage of meiosis I: chromosomes condense and pair, CROSSING OVER takes place, the nuclear membrane breaks down, and the spindle form
  129. Prophase II
    Stage of meiosis II after interkinesis: chromosomes condense, the nuclear membrane breaks down, and the spindle forms
  130. Pseudoautosomal region
    Small region of the X and Y chromosomes that contain homo gene sequences
  131. Punnett square
    Shorthand method of determining the outcome of a genetic cross. The alleles in the gametes are combined to form genotypes of offspring
  132. Quantitative characteristic
    Continuous characteristic; displays a large # of possible phenotypes, which must be described by a quantitative measurement
  133. Recessive
    Refers to an allele or phenotype that is expressed only when homo (not expressed in hetero)
  134. Reciprocal crosses
    Crosses in which the phenotypes of the male and female parents are reversed. Ex. a tall male is crossed w/ short female, and in other cross short male cross w/ tall female
  135. Recombinant gamete
    Possesses new combinations of genes
  136. Recombinant progeny
    Possesses new combinations of traits formed from recombinant gametes
  137. Recombination
    Sorting of alleles into new combinations
  138. Recombination frequency
    Proportion of recombinant progeny produced in a cross
  139. Repulsion (trans) configuration
    Arrangement in which each chromosome contains 1 wild-type (dominant) gene and 1 mutant (recessive) gene. "repulsion"
  140. Secondary spermatocyte
    Product of meiosis I in male
  141. Sequential hermaphroditism
    Phenomenon in which the sex of an individual organism changes in the course of its lifetime; the organism is male at one age or developmental stage and female at a diff age or stage
  142. Sex
    Male or female
  143. Sex chromosome
    Chromosomes that differ morphologically or in number in males and females
  144. Sex determination
    Specification of sex; __ mechanisms include chromosomal, genic, and environmental __ systems
  145. Sex-determining region Y (SRY) gene
    On the Y chromosome, a gene that triggers male development (aka testis-determining factor (TDF) gene
  146. Sex-influenced characteristic
    Encoded by autosomal genes that are more readily expressed in one sex. Ex, an autosomal dominant gene may have higher penetrance in males than in females or an autosomal gene may be dominant in males but recessive in females
  147. Sex-limited characteristic
    Encoded by autosomal genes and expressed in only one sex. Both males and females carry genes for __ but the characteristics appear in only one of the sexes
  148. Sex-linked characteristic
    Characteristic determined by a gene or genes on sex chromosomes
  149. Sister chromatid
    2 copies of a chromosome that are held together at the centromere. Each __ consists of a single DNA molecule
  150. Spermatid
    Immediate product of meiosis II in spermatogenesis; matures to sperm
  151. Spermatogenesis
    Sperm production in animals
  152. Spermatogonium
    Diploid cell in the testis; capable of undergoing meiosis to produce a sperm
  153. Synapsis
    Close pairing of homo chromosomes
  154. Telomere
    Stable end of a chromosome
  155. Telophase
    Stage of mitosis: the chromosomes arrive at the spindle poles, the nuclear membrane re-forms, and chromosomes relax and lenghten
  156. Telophase I/II
    Stage in meiosis: chromosomes arrive at spindle poles
  157. Temperature-sensitive allele
    Expressed only at certain temps
  158. Testcross
    A cross btw an individual w/ an unknown genotype and an individual w/ the HOMO RECESSIVE genotype
  159. Tetrad
    The 4 products of meiosis; all 4 chromatids of a homo pair of chromosomes
  160. Three-point testcross
    Cross btw an individual HETERO at 3 loci and an individual HOMO for RECESSIVE alleles at those loci
  161. Transmission genetics
    Field of genetics that encompasses the basic principles of genetics and how traits are inherited
  162. Triplo-X syndrome
    Human condition in which cells contain 3 X chromosomes. A person w/ __ has a female phenotype q/o distinctive features other than a tendency to be tall and thin; a few such women are sterile, but many menstruate reg and are fertile
  163. Turner syndrome
    Human condition in which cells contain a single X chromosome and no Y chromosome (XO). They are female in appearance but do not undergo puberty and have poorly developed female secondary sex characteristics; most are sterile but have normal intelligence
  164. Two-point testcross
    Cross btw an individual HETERO at 2 loci and an individual HOMO for RECESSIVE alleles at those loci
  165. Ultrasonography
    Procedure for visualizing the fetus. High-freq sound is beamed into the uterus. Sound waves that encounter dense tissue bounce back and are transformed into a pic of the fetus
  166. Wild type
    The trait or allele that is most commonly found in natural (wild) populations
  167. X-linked characteristic
    Characteristic determined by a gene or genes on the X chromosome
  168. X:A ratio
    Ratio of the # X chromosomes to the # of haploid autosomal sets of chromosomes; determines sex in fruit flies
  169. Y-linked characteristic
    Characteristic determined by a gene or genes on the Y chromosome