Chapter 15 Flashcards
Wild type
Phenotype most commonly observed in natural populations
When does signs of sex begin to emerge in fetus
2 months
Sex-linked genes
Gene located on a sex chromosome
Where are most sex-linked chromosomes found
X chromosomes
X-linked genes
Genes found on X chromosomes
Y-linked
Genes found on Y chromosomes
Hemizygous
Only have 1 locus for an allele. Applies to male sex chromosomes
Barr body
Highly condensed inactivated X chromosome
Linked genes
Genes located close enough together on a chromosome that they tend to be inherited together
Genetic recombination
Production of offspring with combination of traits that differ from those found in either parent
Parental types
An offspring with a phenotype that matches one of the true-breeding phenotypes
Recombinant types
Offspring whose phenotype differs from that of the true breeding P generation parents
Frequency of recombination of unlinked genes
50%
Genetic map
Ordered list of genetic loci along a chromosome
Linkage map
A genetic map based on frequencies of recombination between markers during cross over of homologs
Map units
Unit of measurement of the distance between genes.
Nondisjunction
An error in meiosis or mitosis in which members of a pair of chromosomes fail to separate
Aneuploidy
A chromosomal alteration where one or more chromosomes have extra copies or deficient in number
Monosomic
Diploid cell that has only one copy of a particular chromosome
Trisomic
Diploid cell that has 3 copies of a particular chromosome
Polyploidy
Chromosomal alteration where the organism possesses more than one chromosome sets
Deletion
Deficiency in a chromosome resulting from loss of a fragment through breakage
Duplication
Alteration in chromosome structure due to fusion with fragment from a homolog
Inversion
Alteration of chromosome from reattachment of chromosomal fragment in a reverse orientation to the chromosome from the original
Translocation
Alteration in chromosome from attachment of a chromosomal fragment to a non homologous chromosome
Genomic imprinting
expression of an allele in offspring depends on whether the allele is inherited from male or female parent
Result of genomic imprinting
Silencing of allele of a gene
When does genomic imprinting occur
Gamete formation (meiosis)
Extranuclear genes
Genes found outside the nucleus
