Bio test 4 ch 15

emmajohnson's version from 2015-04-29 01:12

Section 1

Question Answer
chromosome theory of inheritanceA 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.
wild typeThe phenotype most commonly observed in natural populations; also refers to the individual with that phenotype.
sex-linked geneA gene located on either sex


Question Answer
X-linked geneA gene located on the X chromosome; such genes show a distinctive pattern of inheritance.
Duchenne muscular dystrophyA human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue.
hemophiliaA 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.
Barr bodyA dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome.

Section 2

Question Answer
linked genesGenes located close enough together on a chromosome that they tend to be inherited together.
genetic recombinationGeneral term for the production of offspring with combinations of traits that differ from those found in either parent.
parental typeAn offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotype itself.
recombinant types (recombinants)An offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself.
crossing overThe reciprocal exchange of genetic material between non-sister chromatids during prophase I of meiosis.
genetic mapAn ordered list of genetic loci (genes or other genetic markers) along a chromosome.
linkage mapA genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes.
cytogenic mapsA map of a chromosome that locates genes with respect to chromosomal features distinguishable in a microscope.

Section 3

Question Answer
nondisjunctionAn 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.
aneuploidyA chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
monosomicReferring to a diploid cell that has only one copy of a particular chromosome instead of the normal two.
trisomicReferring to a diploid cell that has three copies of a particular chromosome instead of the normal two.
polyploidyA chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division.
deletion(1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene.
duplicationAn aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated.
inversionAn aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated.
translocation(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 nutrients in the phloem of vascular plants.
Down syndromeA human genetic disease usu- ally 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.
genetic imprintingA phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.

Section 4