Chapter 12 Flashcards
A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number
Aneuploidy
A dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome
Barr body
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
Chromosome theory of inheritance
The reciprocal exchange of genetic material between no sister chromatids during prophase 1 of meiosis
Crossing over
A map of a chromosome that located genes with respect to chromosomal features distinguishable in a microscope
Cytogenetic map
(1) A deficiency in a chromosomes resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene
Deletion
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 or non life threatening
Down syndrome
A human genetic disease caused by a sex linked recessive allele; characterized by progressive weakening and a loss of muscle tissue
Duchenne muscular dystrophy
An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated
Duplication
An ordered list of genetic loci (genes or other genetic markers) along a chromosome
Genetic map
General term for the production of offspring with combination of traits that differ from those found in either parent
Genetic recombination
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
Hemophilia
An aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated
Inversion
A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes
Linkage map
Genes located close enough together on a chromosome that they tend to be inherited together
Linkage genes
A unit of measurement of the distance between genes. One map is equivalent to a 1% recombination frequency
Map unit
Referring to a diploid cell that has only one copy of a particular chromosome instead of the normal two
Monosomic
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or sister chromatids fail to separate properly from each other
Nondisjunction
An offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotypes itself
Parental type
A chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division
Polyploidy
An offspring whose phenotype differs from that of the true-breeding P generation parents; also refers the the phenotype itself
Recombinant type
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
Sex-linked gene
(1) An aberration in chromosome structure resulting from attachment of a chromosomal fragment to a non homologous chromosome (2) During protein 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 nutrient in the phloem of vascular plants
Translocation
Referring to a diploid cell that had three copies of a particular chromosome instead of the normal two
Trisomic
The phenotype most commonly observed in natural populations; also refers to the individual with that phenotype
Wild type
A gene located on the X chromosome; such genes show a distinctive pattern of inheritance
X-linked gene
