chapter 4
Order by
56 terms
English | Math / Symbols |
|---|---|
 meiosis produces | haploid gametes |
| fertilization produces | diploid zygotes |
| autosomes | nonsex chromosomes |
| the letter O signifies the | absence of a sex chromosome |
| heterogametic sex | when males produce two different types of gametes with respect to the sex chromosomes |
| homogametic sex | when females produce gametes that are all the same with respect to the sex chromosomes |
| pseudoautosomal region | small region of the X and Y chromosomes that contains homologous gene sequences |
| genic sex determination | sex determination in which the sexual phenotype is specified by genes at one or more loci, but there are no obvious differences in the chromosomes of males and females |
| 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 different from that if it is inherited from the mother |
| genic balance system | sex determining system in which sexual phenotype is controlled by a balance between genes on the X chromosome and genes on the autosomes |
| Turner Syndrome | 1. females 2. underdeveloped secondary sex characteristics 3. sterile 4. chromosome complement - XO |
| Klinefelter Syndrome | 1. feminine males 2. small testes, sterile 3. reduced facial hair 4. chromosome complement - cells have one or more y chromosome, XXY, XXXY, XXYY |
| Poly-X females | 1. females 2. few are sterile, most menstruate regularly 3. severity of mental retardation increases with the amount of X chromosomes 4. chromosome complement - XXX+ |
| Barr Body | condensed, darkly staining structure that is found in most cells of female placental mammals and is an inactivated X chromosome |
| When does random X inactivation takes place? | Early in development, within the first weeks of development |
| dominance | the idea that an individual organism possesses two different alleles for a characteristic, but the trait encoded by only one of the alleles is observed in the phenotype |
| incomplete dominance | an intermediate phenotype between two homozygotes |
| codominance | the heterozygote expresses the phenotypes of both homozygotes (think AB blood type) |
| Dominance | Phenotype of the heterozygote is the same as the phenotype of one of the homozygotes. |
| Incomplete Dominance | Phenotype of the heterozygote is intermediate (falls within the range) between the phenotypes of the two homozygotes |
| Codominance | Phenotype of the heterozygote includes the phenotypes of both homozygotes |
| dominance is an __________ ______________ | allelic interaction |
| an allelic interaction is | the interaction between the products of genes |
| Incomplete Penetrance | Refers to a genotype that does not always express the expected phenotypes. When an individual will possess the genotype but does not always express the phenotype - EX. polydactyly |
| Penetrance | Percentage of individuals with a particular genotype that express the phenotype expected of that genotype |
| Expressivity | the degree to which a character is expressed |
| (T or F) Incomplete Penetrance and variable expressivity are due to the effects of other genes and to environmental factors that can alter or completely suppress the effect of a particular gene. | T |
| 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 lethal alleles kill individual organisms that are homozygous for the allele; dominant lethals kill both heterozygotes and homozygotes |
| An example of a dominant lethal allele is: | Huntington's Disease |
| Multiple Alleles | presence in a group of individuals of more than two alleles at a locus |
| gene interaction | type of interaction between the effects of genes at different loci (genes that are not allelic) |
| epistatic gene | a gene that does the masking |
| epistasis | type of gene interaction in which a gene at one locus masks or suppresses the effects of a gene at a different locus |
| hypostatic gene | gene that is masked or suppressed by the action of a gene at a different locus |
| when a probability associated with the chi-square value is >.05 | there is a good fit between the observed results and the ratio |
| complementation test | test designed to determine whether two different mutations are at the same locus (are allelic) or at different loci (are nonallelic). |
| complementation | two different mutations in the heterozygous condition are exhibited as the wild-type phenotype; indicates that the mutations are at different loci |
| cytoplasmic inheritance | inheritance of characteristics encoded by genes located in the cytoplasm, because cytoplasm is usually contributed entirely by only one parent, most cytoplasmically inherited characteristics are inherited from a single parent |
| sex-influenced characteristics | encoded by autosomal genes that are more readily expressed in one sex. |
| sex-limited characteristics | characteristic determined by a gene or genes on sex chromosomes |
| genetic maternal effect | determines the phenotype of an offspring. 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 |
| epigenetics | Phenomena due to alterations to DNA that do not include changes in the base sequence; often affect the way in which DNA sequences are expressed. Alterations are often stable and heritable in the sense that they are passed from one cell to another |
| Norm of Reaction | range of phenotypes produced by a particular genotype in different environmental conditions |
| Sex-linked characteristics | Genes located on the sex chromosome |
| Sex-influenced characteristics | Genes on autosomal chromosomes that are more readily expressed in one sex |
| Sex-limited characteristics | Autosomal genes whose expression is limited to one sex |
| Genetic maternal effect | Nuclear genotype of the maternal parent |
| Cytoplasmic inheritance | Cytoplasmic genes, which are usually inherited entirely from only one parent |
| Genomic imprinting | Genes whose expression is affected by the sex of the transmitting parent |
| Phenocopy | phenotype that is produced by environmental effects is the same as the phenotype produced by a genotype |
| discontinuous (meristic) characteristics | have a few easily distinguished phenotypes (blood type) |
| continuous characteristics | characteristics that exhibit a continuous distribution of phenotypes (height, weight) |
| continuous characteristics are also called | quantitative characteristics |
| polygenic characteristics | characteristics that are encoded by genes at many loci |
| pleiotropy | one gene affects multiple characteristics |
| multifactorial characteristics | many continuous characteristics both polygenic and influenced by environmental factors |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.