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Gen Exam 1
Question | Answer |
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Genome | Complete set of genetic instructions for an organism |
Trnamission Genetics | Field of genetics that encompasses the basic principles of genetics and how traits are inherited |
Molecular Genetics | Study of the chemical nature of genetic information and how it is encoded |
Population Genetics | study of the genetic composition of populations and how a pop's collective group of genes changes with the passage of time |
Model Genetic Organism | an organism that is widely used in genetic studies because it has characteristics , such as short generation time and large numbers of progeny, that make it well suited to genetic analysis |
Pangenesis | Early concept of heredity proposing that particles carry genetic information from different parts of the body to the reproductive organs. |
Inheritance Of Acquired Characteristics | early notion of inheritance proposing that acquired traits are passed to descendants. |
Preformationism | early concept of inheritance proposing that a miniature adult resides in either the egg or the sperm and increases in size during developmentm with all traits beinf inherited from the parent that contributes to homunculus |
Blending Inheritance | early concept of heredity proposing that offspring possess a mixture of of the traits from both parents |
Cell theory | states that all life is composed of cells, that cells arise only from other cells, and that the cell is the fundamental unit of structure and function in livign organisms |
Germ-plasm theory | states that cells in the reproductive organs carry a complete set of genetic information |
Prokaryote | unicellular organism with a simple cell structure, include eubacteria and archea |
eukaryote | organism with a complex cell structure including a nuclear envelope and membrane bounded organelles. 1 of the 3 primary divsions of life, include unicellular and multicellular forms |
eubacteria | 1 of the 3 primary divisions of life. consists of unicellular organisms with prokaryotic cells and include most of common bacteria |
archaea | 1 of the 3 primary divisions of life. archaea consist of unicellular organisms with prokaryotic cells |
nucleus | space in eukaryotic cell that is enclosed by the nuclear envelope and contains the chromosomes |
histone | low-molecular-weight protein found in eukaryotes that complexes with DNA to form chromosomes |
Chromatin | material found in the eukaryotic nucleaus; consists of DNA and proteins. |
homologous pair | 2 chromosomes that are alike in structure and size and that carry genetic information for the same set of heredity characteristics. one inherited from the male parent and one from the female parent. |
diploid | possessing two sets of chromosomes (2 genomes) |
haploid | possessing a single set of chromosomes (one genome) |
telomere | stable end of a chromosome |
sister chromatid | 2 copies of a chromosome that are held together at the centromere. each chromatid consists of a single DNA molecule. |
cell cycle | stages through which a cell passes from one cell division to the next |
interphase | period in the cell cycle b/w the cell divisions. In interphase, the cell grows, develops, and prepares for cell division |
M Phase | period of active cell division; includes mitosis and cytokinesis |
mitosis | process by which the nucleus of a eukaryotic cell divides |
cytokinesis | process by which the cytoplasm of a cell divides |
prophase | stage of mitosis. In prophase, the chromosomes contract and become visible, the cytoskeleton breaks down, and the mitotic spindle begins to form |
metaphase | stage of mitosis, chromosomes algin in the center of the cell |
anaphase | stage of mitosis in which chromatids seperate and move toward the spindle poles |
telophase | stage of mitosis, chromosomes arrive at the spindle poles, the nuclear membrane re forms and the chromosomes relax and lengthen |
meiosis | process in which chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells. consists of 2 divisions meiosis I and II |
fertilization | fusion of gametes or sex cells to form a gamete |
prophase I | stage in meiosis I, chromosomes condense and pair, crossing over takes place, the nuclear membrane breaks down, and the spindle forms |
synapsis | close pairing of homologous chromosomes |
bivalent | refers to a synapsed pair of homologous chromosomes |
tetrad | the four products of meiosis; all 4 chromatids of a homologous pair of chromosomes |
crossing over | exchange of genetic material b/w homologous but nonsister chromatids |
metaphase I | stage of meiosis I, homologous pairs of chromosomes align in the center of the cell |
anaphase I | stage in meiosis I, homologous chromosomes seperate and move toward the spindle poles |
telophase I | stage of meiosis I chromosomes arrive at spindle poles |
Prophase II | stage of meiosis after interkinesis, chromosomes condense, the nuclear membrane breaks down, and the spindle forms |
metaphase II | stage of meiosis II, indivudual chromosomes align at the metaphase plate |
anaphase II | stage of meiosis II, chromatids se[erate and move toward spindle poles |
telophase II | stage of meiosis II, chromosomes arrive at spindle poles |
recombination | sorting of alleles into new combinations |
spermatogenesis | sperm production in animals |
oogenesis | egg production in animals |
gene | genetic factor that helps determine a trait. often defined at teh molecular level as a DNA sequence that is transscribed into an RNA molecule |
allele | one of two or more alternate forms of a gene |
Locus | Position on a chromosome where a specific gene is located |
genotype | the set of genes possessed by an individual organism |
homozygous | refers to an individual organism that posseses two identical alleles at a locus |
heterozygous | refers to an individual organism that posseses two different alleles at a locus |
phenotype | appearance of a characteristic |
monohybrid cross | A cross b/w 2 individuals that differ in a single characteristic, a cross b/w individuals that are homo. for different alleles at the same locus (AA x aa) or (Aa x Aa) |
P (parental) generation | first set of parents in a genetic cross |
F1 (First Filial) generation | offspring of the initial parents in a genetic cross |
F2 (Second Filial) generation | offspring of the F1 generation ina genetic cross |
dominant | refers to an allele or a phenotype that is expressed in homozygous (AA) and in heterozygous (Aa) |
recessive | refers to an allele or phenotype that is expressed only when homozygous |
principle of segregation | important princicple of heredity discovered by Mendel that states that each diploid individual posseses 2 alleles at a locus and that these 2 alleles seperate when gametes are formed, 1 allele to each gamete |
Concept of Dominance | Principle of heredity discovered by Mendel, when 2 different alleles are present in a genotype, only one allele may be expressed in the phenotype. The dominant allele is the allele that is expressed, amd recessive is not |
Chromosome theory of inheritance | al |
Backcross | Cross b/w an F1 individual and one of the parental genotypes |
Punnett Square | shorthand method of determining the outcome of a genetic cross. the gametes of one parent are written along the upper edge and the gametes of the other parent are written on left edge. |
probability | likelihood of a particular event occuring; the number of times that a particular event occurs divided by the number of all possible outcomes. Prob. values range from 0 to 1 |
Multiplication rule | states that the probablity of 2 or more independent events occuring together is calculated by multiplying the probabilities of each of the independent events |
addition rule | states that the probablity of any of 2 or more mutually exclusive events occuring is calculated by adding the probablities of the indiviidual events |
test cross | a cross b/w an individual with an unknown genotype and an individual with the homozygous recessive genotype |
incomplete dominance | refers to the phenotype of a heterozygous that is intermediate b/w the phenotypes of the two homozygotes |
wild type | the trait or allele that is most commonly found in natural populations |
Dihybrid cross | a cross b/w 2 individuals that differ in 2 characteristics, a cross b/w individuals that are homozygous for differnt alleles at the 2 loci (AABB x aabb) or ( AaBb x AaBb) |
principle of independent assortment | genes encoding differnt characteristics seperate independently; applies only to genes located on different chromosomes or to genes far apart on the same chromosomes |
goodness-of-fit chi-square | statistical test used to evaluate how well a set of observed values fit the expected values. The probablitly associated with chi value is the prob. that the differences b/w the observed and the expected values may be due to chance |
pedigree | pictoral representation of a family history outlining the inheritance of one or more traits or diseases |
proband | a person with a trait or disease for whom a pedigree is constructed |
consanguinity | mating b/w related individuals |
sex | male or female |
sex determination | specification of sex. sex determining mechanisms include chromosomal, genic, and environmental sex-determing systems |
sex chromosome | chromosomes that differ morphologically or in number in males and females |
autosome | chromosome that is the same in males and females; nonsex chromosome |
heterogametic sex | the sex that produces 2 types of gametes with respect to sex chromosomes. |
homogametic sex | the sex that produces gametes that are alike with regard to sex chromosomes |
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 teh chromosomes of male or female |
genic balance system | sex-determining system in which sexual phenotype is controlled by a balance b/w genes on the X chromosome and genes on the autsomes |
X:A ratio | ratio of the number of X chromosomes to the number of haploid autosomal sets of chromosome; determines sex in fruit flies |
turner syndrome | human condition where cells contain a single X chrom. and no Y chrom.(XO) They are female in appereance but do not undergo puberty and have poorly developed female secondary sex characteristics; most are sterile but have normal intelligence |
klinefelter syndrome | human condition in which cells contain one or more Y chromosomes along with mutliple X chromosomes, people are male in appearance but frequently have small testes, slight breast enlargement, and reduced facial and pubic hair. |
Triplo-X syndrome | human condition in which cells contain 3 X chromosomes. People with this have a female phenotype w/o dinstinctive features other than a tendency to be tall and thin. |
sex-determining region gene | On the Y chromosome, a gene that triggers male development; also known as the testes deter. gene |
sex-linked characteristic | char. develop. by a gene or genes on a sex chromosome |
x-linked characteristic | char. deter. by a gene or genes on the x chrom. |
Y-linked characteristic | char. deter. by a gene or genes on the Y chromosomes |
hemizygosity | possession of a single allele at a locus. Males of organisms with XX-XY sex determination are hemizygous for X-linked loci,because their cells possess a single X chromosome. |
dosage compensation | equalization in males and femaled of the amount of protein produced by X-linked genes. |
barr body | condensed, darkly staining structure that is found in most cells of female placental mammals and is an inactivated X chromosome |
lyon hypothesis | prposed by mary Lyon in 1961, this proposes that one X-chromosome in each female cell becomes inactivated (barr body) and suggests that which X becomes inactivated is random and varies from cell to cell. |
Codominaance | type of allel interaction in which the heterzygote simultaneously expresses traits of both homozygotes |
incomplete penetrance | refers to a genotype that does not always express teh expected phenotype. some individuals possess the genotype for a trait but do not express the phenotype. |
penetrance | percentage of individuals with a particular genotype that express the phenotype expected of that genotype. |
expressivity | degree to which a gene os expressed |
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 genetis cross. recessive lethal alleles kill individual organisms rhat are homozygous for the allele; dominant lethals kill |
lethal allle cont. | both heterzygous and homozygotes |
multiple alleles | presence in a group of individuals of more than two allels at a locus. although, for the group the locus has more than 2 alleles, each member of the group has only two of the possible alleles. |
gene interaction | interaction b/w genes at a differnt loci that affct the same characteristic. |
epistatsis | type of gene interaction in which gene at one locus masks or supresses the effects of a gene at a differet locus. |
epistatic gene | masks or supresses the effect of a gene at a different locus |
hypostatic gene | gene that is masked or supressed by the action of a gene at a different locus |
complementation test | test designed to deter. whether two differnt mutations are at the same locus. 2 individuals that are homozygous for 2 independently derived mutations are crossed. |
complementation | 2 different mutations in the heterzygous condotion are exhibited as the wild-type phenotype; indicates that the mutations are at a differnt loci. |
sex-influenced charcteristic | encoded by autosomal genes that are more readily expressed in one sex. for example, 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 |
sex-limited charcterisitc | encoded by autosomal genes and expressed in onyl one sex. Both males and females carry genes for sex-limited char., but the char. appear in only one of the sexes. |
cytoplasmic inheritance | inheritance of characteristics encoded by genes located in the cytoplasm. Because the cytoplasm is usually contributed entirely by only one parent, most cytoplasmically inherited char. are inherited from a single parent |
genetic maternal effect | determines the phenotype of the offspring. with genetic maternal effect, an offspring inherits genes for the characteristics fvrom both parents, but hte offspring's phenotype is determined not by its own genotype but by the nuclear genotype of its mother. |
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 differnt from that if it is inherited from the mother |
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 from one cell to the other. |
temperature-sensitive allele | expressed only at certain temps |
phenocopy | phenotype that is produced by environmental effects and is the same as the phenoycopy produced by a genotype |
discontinous characteristic | exhibits only in a few, easily distinguished phenotypes. An example is seed shape in which seeds are either round or wrinkled |
continous characteristic | displays a large number of possible phenotypes that are not easily distinguished, such as human height |
quantitative characteristic | continous charcteristic; displays a large nu,ber of possible phenotypes, which must be described by a quantitative measurement |
polygenic characteristic | encoded by genes at many loci |
pleitropy | a single genotype influences many phenotypes |
multifactoral characteristic | determined by many multiple genes and environmental factors. |