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Definition
| a dense object lying along the inside of a nuclear envelope in cells of female mammals, representing highly condensed, inactivated X chromosome |
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Definition
| a linking enzyme essential for DNA replication; catalyzes the covalent bonding of the3' end of one DNA fragment (such as an Okazaki fragment) to the 5' end of another DNA fragment (such as a growing DNA chain) |
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Definition
| an enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3' end of an existing chain. There are several different DNA polymerases; DNA polymerase iii and DNA polymerase i play major roles in DNA replication in E. coli |
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Definition
| the process by which a DNA molecule is copied; also called DNA synthesis |
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Definition
| a human genetic disease usually caused by the presence of an extra chromosome 21; characterized by developmental delays and heart and other defects that are generally treatable and non-life-threatening |
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Term
| Duchenne muscular dystrophy |
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Definition
| a human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue |
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Definition
| the first filial, hybrid (heterozygous) offspring arising from a parental (P generation) cross |
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Definition
| a human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms |
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Definition
| a short segment of DNA synthesized awat from the replication fork on a template strand during DNA replication. Many such segments are joined together to make up the lagging strand of the newly synthesized DNA |
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Definition
| the true-breeding (homozygous) parent individuals from which F1 hybrid offspring are derived in studies of inheritance; P stands for "parental." |
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Definition
| a human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and mental performance usually become manifest a few months after bitch, followed by death within a few years |
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Definition
| a rule of probability stating that the probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilities |
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Definition
| any of the alternative versions of a gene that may produce distinguishable phenotypic effects |
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Definition
| a technique associated with prenatal diagnosis in which amniotic fluid is obtained by aspiration from needle inserted into the uterus. the fluid and the fetal cells it contains are analyzed to detect certain genetic and congenital defects in the fetus |
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Definition
| a chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number |
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Definition
| referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5'- 3' directions). |
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Definition
| a virus that infects bacteria; also called a phage |
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Definition
| in genetics, an individual who is heterozygous at a given genetic locus for a recessively inherited disorder. The heterozygote is generally phenotypically normal for the disorder but can pass on to the recessive allele to offspring |
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Definition
| an observable heritable feature that may vary among individuals |
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Definition
| the complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope |
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Term
| chromosome theory of inheritance |
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Definition
| a basic principle in biology stating that genes are located at specific positions (loci) on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns |
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Term
| choronic villus sampling (CVS) |
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Definition
| a technique associated with prenatal diagnosis in which a small sample of the fetal portion of the placenta is removed for analysis to detect certain genetic and congenital defects in the fetus |
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Definition
| the situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways |
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Definition
| the situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable |
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Term
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Definition
| the reciprocal exchange of genetic material between nonsister chromatids during prophase 1 of meiosis |
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Definition
| a map of chromosomes that locates genes with respect to chromosomal features distinguishable in a microscope |
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Definition
(1) a deficiency in a chromosome resulting from the loss of a fragment through breakage.
(2) a mutational loss of one of more nucleotide pairs from a gene |
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Term
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Definition
| an organism that is heterozygous with respect to two genes of interest. All the offspring from a cross between parents doubly homozygous for different alleles are dihybrids. For example. parents of genotypes AABB and aabb produce a dihybrid of genotype AaBb. |
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Definition
| a cross between two organisms that are each heterozygous for both of the characters being followed (or the self-pollination of a plant that is heterozygous for both characters). |
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Definition
| an allele that is fully expressed in the phenotype of a heterozygote |
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Definition
| the form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape |
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Definition
| an aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated |
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Definition
| a type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene |
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Definition
| the less condensed form of eukaryotic chromatin that is available for transcription |
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Definition
| the offspring resulting from interbreeding (or self-pollination) of the hybrid F1 generation |
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Term
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Definition
| an ordered list of genetic loci (genes or other genetic markers) along a chromosome |
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Term
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Definition
| general term for the production of offspring with combinations of traits that differ from those found in either parent |
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Term
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Definition
| 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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Definition
| the genetic makeup, or set of alleles, of an organism |
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Definition
| an enzyme that untwists the double helix of DNA at replication forms, separating the two stands and making them available as template strands |
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Definition
| a human genetic disease caused by a sex-linked recessive allele resulting in the absence of one or more blood-clotting proteins; characterized by excessive bleeding following injury |
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Definition
| eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed |
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Definition
| having two different alleles for a different gene |
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Definition
| having two identical alleles for a given gene |
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Term
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Definition
| in genetics, the mating, or crossing, of two true-breeding varieties |
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Term
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Definition
| the situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele |
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Term
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Definition
| an aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated |
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Term
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Definition
| a discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5'-3' direction away from the replication fork |
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Term
| law of independent assortment |
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Definition
| Mendel's second law, stating that each pair of alleles segregated, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes |
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Term
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Definition
| Mendel's first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation |
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Term
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Definition
| the new complimentary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5'-3' direction |
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Definition
| a genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes |
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Term
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Definition
| genes located close enough together on a chromosome that they tend to be inherited together |
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Term
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Definition
| a unit of measurement of the distance between genes. One map unit is equivalent to a 1% recombination frequency |
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Term
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Definition
| the cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides |
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Term
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Definition
| a cross between two organisms that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant) |
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Term
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Definition
| an organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. For example, parents of genotype AA and aa produce a monohybrid of genotype Aa |
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Term
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Definition
| referring to a diploid cell that has only one copy of a particular chromosome instead of the normal two |
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Term
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Definition
| referring to a phenotypic character that is influenced by multiple genes and environmental factors |
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Term
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Definition
| a rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities |
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Definition
| an error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other |
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Term
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Definition
| the range of phenotypes produced by a single genotype, due to environmental influences |
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Term
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Definition
| an enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides |
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Term
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Definition
| a non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated |
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Term
| nucleotide excision repair |
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Definition
| a repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide |
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Term
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Definition
| site where the replication of DNA molecule begins, consisting of a specific sequence of nucleotides |
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Term
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Definition
| an offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotype itself |
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Term
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Definition
| a diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations |
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Term
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Definition
| the observable physical and physiological traits of an organism, which are determined by its genetic makeup |
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Term
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Definition
| the ability of a single gene to have multiple effects |
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Term
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Definition
| an additive effect of two or more genes on a single phenotypic character |
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Term
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Definition
| a chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division |
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Term
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Definition
| an enzyme that joins RNA nucleotides to make a primer during DNA replication |
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Term
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Definition
| a short stretch of RNA with a free 3' end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication |
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Term
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Definition
| a diagram used in the study of inheritance to show the predicted genotypic results of random fertilization in genetic crosses between the individuals of known genotype |
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Term
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Definition
| a heritable feature that varies continuously over a range rather than in an either-or-fashion |
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Term
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Definition
| an allele whose phenotypic effect is not observed in a heterozygote |
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Term
| recombinant type (recombinant) |
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Definition
| an offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself |
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Term
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Definition
| a Y-shaped region on a replicating DNA molecule where the parental stands are being unwound and new strands are being synthesized |
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Term
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Definition
| type of DNA replication in which the replicated double helix consists of one old strand, derived from the parental molecule, and only one newly made strand |
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Term
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Definition
| a gene located on either sex chromosome. Most sex-linked genes are on the X chromosome and show distinctive patterns of inheritance; there are very few genes on the Y chromosome. |
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Term
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Definition
| a recessively inherited human blood disorder in which a single nucleotide change in the B-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symtoms in afflicted individuals |
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Term
| single-strand binding protiens |
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Definition
| a protein that binds to the unpaired DNA strands during DNA replication, stabilizing them and holding them apart while they serve as te,plated for the synthesis of complementary strands of DNA |
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Term
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Definition
| an enzyme that catalyzes the lengthening of telemores in eukaryotic germ cells |
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Term
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Definition
| the tandemly repetitive DNA at the end of a eukaryotic chromosome's DNA molecule. Telomeres protect the organism's genes from being eroded during successive rounds of replication. See also repetitive DNA |
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Term
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Definition
| breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring reveals the unknown genotype |
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Term
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Definition
| a protein that breaks, swivels, and rejoins DNA strands. During DNA replication, topoisomerase helps to relieve strain in the double helix ahead of the replication fork |
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Term
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Definition
| one of two more detectable variants in a genetic character |
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Term
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Definition
(1) the conversion of a normal animal cell to a cancerous cell
(2) a change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer |
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Term
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Definition
(1) an aberration in chromosome structure resulting from attachment of a chromosomal fragment to a non-homologous chromosome
(2) during protien synthesis, the third stage in the elongation cycle, when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome
(3) the transport of organic nutrients in the phloem of vascular plants |
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Term
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Definition
| referring to a diploid cell that has three copies of a particular chromosome instead of the normal two |
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Definition
| referring to organisms that produce offspring of the same variety over many generations of self-pollination |
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Definition
| an infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope |
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Definition
| the phenotype more commonly observed in natural populations; also refers to the individual with that phenotype |
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Term
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Definition
| a gene located on the x chromosome; such genes show distinctive pattern of inheritance |
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