Unit 5 - Meiosis, Genetics, & Pedigrees Flashcards
Meiosis
daughter cells with 1/2 numbers of chromosomes from parent cells
Meiosis phases
P I: homologous chromosomes
M I: crossing over
A I: full chromosome pairs separated
T I and cytokinesis: ends with haploid cells
Recombinant chromosomes
non sister chromatids but the same trait is switched
Dihybrid cross
F1 hetero - 9:3:3:1
shows independent assortment: the factors controlling the traits are inherited independent of one another
Autosomal Dominant
parent is most likely affected
Autosomal Recessive
parent is most likely unaffected
X-linked traits
Males are more affected than females
Multiple Alleles
More than one allele for a trait (blood type)
Codominance
More than one allele is dominant; two alleles are dominant to one other
spots on a cow
Incomplete Dominance
mix of the traits
a red and white flower have a pink offspring
Non-nuclear inheritance
Mitochondrial DNA
- Inherited from mother’s egg
- Passed on by mother to each child
- Males and females can be equally affected by characteristics passed on this way
Genetically Linked
genes located near each other on the same chromosome tend to be inherited together
Linked: Recombinant < 50%; less likely for crossing over
Unlinked: 50% parental phenotype, 50% recombinant; more likely for crossing over
Epistasis
phenotypic expression of a gene at one place on chromosome (locus) will effect a gene at another locus
1 gene codes for pigment and another will determine if the pigment shows up or not
Polygenetic Inheritance
effect of 2 or more genes acting on one phenotype
height, human skin color – a spectrum
Disjunction
chromosomes fail to separate properly in meiosis anaphase I/II
