PGX lecture 2

• the entire complement of genetic material in a chromosome set.
• an organism’s unique and complete set of genetic
• information (DNA)

a linear end-to -end arrangement of genes and other DNA, sometimes with associated protein and RNA

the fundamental physical and functional unit of heredity, which carries information from one generation to the next; a segment of DNA composed of a transcribed region and a regulatory sequence that makes transcription possible

• deoxyribonucleic acid
• a chain of linked nucleotides (having deoxyribose as their sugars). Two such chains in double helical form are the fundamental substance of which genes are composed.

a cell having one chromosome set or an organism composed of such cells

a cell having two chromosome sets or an individual organism having two chromosome sets in each of its cells

the basic unit of eukaryotic chromosome structure; a ball of eight histone molecules that is wrapped by two coils of DNA

• the substance of chromosomes; now known to include DNA and chromosomal proteins.
• condense chromatin = chromosome

• densely staining condensed chromosomal regions, believed to be for the most part genetically inert.
• dense packing, dark staining, generally inactive

• a less-condensed chromosomal region, thought to contain most of the normally functioning genes.
• looser packing, lighter staining, more active (transcriptionally)

• a specialized region of DNA on each eukaryotic chromosome that acts as a site for the binding of kinetochore proteins.
• dense chromatin near “center” ofchromosome

• the tip, or end, of a chromosome.
• the “tips” of a chromosome, also somewhat dense – think of it as the knots that keep a chromosome from unraveling

• any chromosome that is not a sex chromosome.
• autosomal chromosome --> 22 pairs --> does not differ male to female

• a chromosome whose presence or absence is correlated with the sex of the bearer; a chromosome that plays a role in sex determination.
• sex linked --> the XX or XY pair

• aka intervening sequence
• a segment of largely unknown function within a gene. This segment is initially transcribed, but the transcript not found in the functional mRNA.
• The non-expressed (transcribed but not translated) portion of the coding sequence of a gene.

• any nonintron section of the coding sequence of a gene; together, the exons correspond to the mRNA that is translated into protein.
• the expressed (transcribed and translated) portion of the coding sequence

The space between genes. Not transcribed or translated but may serve a regulatory function.

• one of the different forms of a gene that can exist at a single locus.
• a form or variant of a gene. Usually comes in “wild type” and “mutant(s)”. Wild type is usually defined as the most common form (and is often dominant to any variants/mutants). In a population there can be multiple alleles.

refers to the state of carrying a pair of identical alleles at one locus

refers to the state of carrying a pair of different alleles at one locus

• (1) the form taken by some character (or group of characters) in a specific individual. (2) the detectable outward manifestations of a specific genotype.
• Observable expression of genotype. Morphological, biochemical, physiological or behavioral trait. Changes throughout life; influenced by environment & development.
• Phenotype = genotype x environment x development

• the specific allelic composition of a cell - either of the entire cell or, more commonly, of a certain gene or a set of genes.
• Gene(s) associated with a given trait. Essentially a fixed character of an organism (except for rare mutations).

• a type of nuclear division (occurring at cell division) that produces two daughter nuclei identical with the parent nucleus.
• “conservative” division mother and daughter cells identical

• two successive nuclear divisions (with corresponding cell divisions) that produce gametes (in animals) or sexual spores (in plants and fungi) that have one-half of the genetic material of the original cell.
• “reductive” division mother and daughter cells different

• (1) four homologous chromatids in a bundle in the first meiotic prophase and metaphase. (2) the four haploid product cells from a single meiosis.
• Four homologous chromatids in a bundle in the first meiotic prophase and metaphase

a pair of sister chromatids joined at the centromere, as in the first division of meiosis.

• one of the two side-by-side replicas produced by chromosome division.
• together in the "x" formation

• a member of a pair of homologous chromosome.
• The two members of a chromosome pair in a cell

a gene present in only one copy in a diploid organism - for example, an X-linked gene in a male mammal.

• equal numbers of progeny genotypes attributable to the separation of two alleles of one gene at meiosis.
• Mendel's first law:
• the two members of a gene pair segregate from each other in meiosis; each gamete has an equal probability of obtaining either member of the gene pair

• Mendel's second law:
• unlinked or distantly linked segregating gene paris assort independently at meiosis.
• gene pairs on different chromosome pairs assort independently at meiosis

• (1) in general, any process in a diploid or partly diploid cell that generates new gene or chromosomal combinations not previously found in that cell or in its progenitors. (2) at meiosis, the process that generates a haploid product of meiosis whose genotype is different from either of the two haploid genotypes that constituted the meiotic diploid.
• Meiosis generates recombinants, which are haploid meiotic products with new combinations of the alleles/chromosomes than carried by the haploid genotypes that united to form the meiocyte.

• aka multiple factor hypothesis
• a hypothesis that explains quantitative variation by assuming the interaction of a large number of genes (polygenes), each with a small additive effect on the character.
• QTL: a gene affecting the phenotypic variation in continuous varying traits such as heigh and weight, among others