Module 4—The Chromosomal Basis of Inheritance Flashcards
mendel’s 3rd law
law of dominance
does not reflect most traits
Schleiden & Schwann
cell theory
Walter Flemming
discovered chromosomes via microscopy
saw they were separated during mitosis
Sutton & Boveri
connected events of meiosis with Mendel’s laws
Thomas Hunt Morgan
fly lab
mapped first genes to specific chromosomes
found by Morgan not to exhibit Mendelian inheritance
sex-linked traits
hemizygous
describes males’ Y chromosome paired with X chromosome
reciprocal cross
cross of mutant father + wild type mother, AND cross of mutant mother + wild type father
homogametic
2 copies of same sex chromosome
female
heterogametic
sex chromosomes differ
male
__________ X chromosome has no effect on sons
paternal
in mammals, sex is determined by….
presence of Y chromosome
gene for testes development
SRY
how mammals deal with double dose of X chromosomes in females
___ bodies
X inactivation
Barr bodies - bound up X chromosome in heterochromatin
can become ovary or testis based on…
bipotential gonad
presence or absence of SRY gene
X-O system
XX is female
X0 is male
Z-W system
ZW is female
ZZ is male
haplo-diploid system
diploids are female
haploids are male
males have no fathers; develop from unfertilized eggs
genic sex determination
genes, not chromosomes, determine sex
environmental sex determination example
temperature determines ratio of males in all the eggs
(reptiles)
linked genes
located close together on same chromosome
gave evidence for recombination that separated linked genes
production of nonparental alleles in small numbers