Genetics Vocab Exam 1(Chp. 1-4)

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DNA

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a macromolecule usually consisiting of antiparallel polynucleaotide chains held together by hydrogen bonds, in which sugar residues are deoxuribose. The primary carrier for genetic information.

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RNA

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a nucleic acid characterized by the sugar ribose and the pyrimidine uracil, usually a single-stranded polynucleotide. Several form are recognized, including ribosomal RNA, bessenger RNA, transfer RNA, and heterogeneous nuclear RNA.

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Protein

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a molecule composed of one or more polypeptides , each compsed on amino acids covalently linked together.

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Inheritance

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explains the transmission of genetic information controlling phenotypic traits

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Genomics

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the study of genomes, including nucleotide sequence, gene content, organization, and gene number

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Proteomics

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the study of the expressed proteins present in a cell at a given time.

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GMO(genetically modified organism)

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a plant or animal that carries a gene from another species transferred to its genome using remcombinant DNA technology, and where the gene is expressed to produce a gene product.

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rRNA: ribosomal RNA

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the RNA molecules that are the structural components of the ribosomal subunits. IN prokaryotes, these are the 16S, 23S, and 5S molecules.

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Ribosomes

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A ribonucleoprotien organelle consisiting of two ribosomal subunits, each contiaing RNA and protein. Ribosomes are the site of translation of mRNA codons into the amino acid sequence of the polypeptide chain.

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Karyotype

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the chromosome complement of a cell or an individual,. Often used to refer to the arrangement of metaphase chromosomes in a sequence according to length and position

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Conditional mutation

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A mutation that expresses under certain (permissive) conditions and a mutant phenotype under other (restrictive) conditions.

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Chromosome

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In prokaryontes, one or more DNA molecules containing the genome : in eukaryontes, a DNA molecule complexed with RNA and proteins to form a threadlike structure containing genetic information arranged in a linear sequence and visible during mitosis and meiosis.

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Chromatid

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One of the longitudinal subunits of a replicated chromosome: iris joined to its sister chromatid at the centromere.

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Sister chromatid

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post s- phase structures of replicated chromosomes they are genetically identical. They are originally attached at the centromere until anaphase of mitosis and anaphase II of meiosis.

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Synaptonemal complex

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an organelle consiting of a triparitie nucleoprotein ribbon that forms between the paired homologous chromosomes in the pachytene stage of the first meiotic division

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Equational division

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a division of each chromosome into longitudinal halves that are distributed into two daughter nuclei. Chromosome division in mitosis is an example of equational division.

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Bivalent

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synapsed homologous chromosomes in the first prophase of meiosis

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Homologous chromosome

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chromosomes that synapse or pair during meiosis. Chromosomes that are identical with respect to their genetic loci and centromere placement

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Synapse

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the pairing of homologous chromosomes during prophase I of meiosis

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Tetrad

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4 chromatids that make up paired homologs in the prophase of the first meiotic division. The four haploid cells produce by a single meiotic division.

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Chiasma

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the crossed strands of nonsister chromatids seen in diploteneof the first meiotic division. Regarded as the cytological evidence for exchange of chromosomal material, or crossing over.

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Cross-over

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the exchange of chromosomal material (parts of chromosomal arms) between homologous chromosomes by breakage and reunion. The exchange of material between nonsister chromatids during meiosis is the basis of genetic recombination.

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F1: F1 generation

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first filial generation the progeny resulting from the first cross in a series

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F2: F2 generation

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filial generation: the progeny resulting from a cross of the F! generation

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Heterozygous

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heteroaygoes are individuals with different alleles at one or more loci. Such an individual will produce unlike gamates and therefore will not breed true

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Genotype

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the specific allelic or genetic constitution of an organism: often, allelic composition of one or a limited number of genes under investigation

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Phenotype

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the observable properties of an organism that are genetically controlled

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Alleles

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are mutated genes that are distinguished from other by phenotypic effects.

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Gametes

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specialized reproductive cells with a haploid number of chromosomes.

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Homozygous

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individuals with identical alleles at one or more loci. These individuals will produce identical gamates and will therefore breed true.

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Test cross

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a cross between an individual whose genotype at one or more loci may be unknown and an individual who is homozygous recessive for the genes in question.

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Null hypothesis

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used ub statustucak tests, it states that there is no difference between the observed and expected data sets. Statistical method such as the chi-square analysis are used to test the probability of this hypothesis

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Pedigree

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in human genetics, a diagram showing the ancestral relationships and transmission of genetic traits over several generation in a family.

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Polymorphism

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the eexistence of two or more discontinuous, segregating phenotypes in a population.

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Antigen

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a molecule, often a cell-surface protein, that is capable of eliciting the formation of antibodies

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Heterochromatin

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the heavily staining , late-replicating regions of chromosomes that are condensed in interphase . Thought to be devoid of structural genes.

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Imprinting

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genomic imprinting is a process whereby a region of either the paternal or maternal chromosome is modified (marked ot imprinted), therbay affecting phenotypic expression. Expression therefore depends upon which parent contributes a mutant allele

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Reciprocal cross

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a paired cross in which the genotype of the female in the first criss is present as the genotype of the male in the second cross, and vice versa

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Penetrance

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the frequency , expressed as a percentage, with which individuals of a given genotype manifest at least some degree of a specific mutant phenotype associated with a trait.

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Expressivity

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the degree or range in which a phenotype fir a given trait is expressed.

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Epistatic(epistais)

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is the nonreciprocal interactionbetween genes such that one gene interferes with or prevents the expression of another gene. In Drosphila for example, the recessive gene eyeless, when homozygous, prevents the expression of eye color genes present in the genome.

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Position effect variegation

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change in expression if a gene associated with a change in the gene’s location within the genome

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P1: parental generation

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the original parents in a breeding experiment. A cross of these parents results in the F1 generation.

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Self fertilization

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when an individual fertilizes its own gamates. This is seen with the F1 generation plants in a breeding experiment (F1 cross). This results in a second generation of plants, the F2 generation.

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Punnett Square

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A visual representation of possible outcomes in breeding. Each of the possible gamets are assigned to and individual column or row. All possible combinations are recorded in boxes corresponding to one of each of the alleles of a gene.

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test cross

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Used when the genotype of an individual expressing a dominant phenotype is unknown. The individual is crossed with a homozygous recessive individual.

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proband

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in pedigree analysis, the individual who's phenotype first brought attention to the investigation.

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gene interaction

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a situation where a single phenotype is affected by more than one gene.