only 1 of the 2 gene copies present in an organism is distributed to each gamete that it makes and the allocation of the gene copies is random
occurs in anaphase 1
law of independent assortment:
inheriting an allele has nothing to do with inheriting an allele for any other trait
occurs during metaphase 1
monohybrid cross: heterozygous for one gene
dihybrid cross: heterozygous for two genes
independent events- the occurrence of one event does NOT affect the occurrence of another (rolling a 1 on the first dice and a 6 on the second dice)
mutually exclusive- two events cannot occur at the same time (rolling a 1 and 6 at the same time)
codominance: two alleles may be simultaneously expressed when both are present
ex. red and white flowers
incomplete dominance: two alleles may produce an intermediate phenotype when both are present
ex. pink flowers
sex linkage: genes carried on sex chromosomes, such as the X chromosome of humans
show different inheritance patterns than genes on autosomal (non-sex) chromosomes
epistasis: the alleles of one gene may mask or conceal the alleles of another gene
polygenic inheritance: characteristics that are controlled by a number of differentgenes
polygenic traits include height, skin color, hair color, and eye color
when doing punnett squares between males and females, the Y chromosome has NO ALLELE on it
X-linked human genetic disorders are much more common in males than in females due to the X-linkedinheritance pattern (the X chromosome from the mom is the ONLY allele that shows up in males)
hemizygous: males are hemizygous for X-linked genes because he has no other gene copy
even if the allele is recessive in females, the male will still express that allele
recombination frequency = (recombinants/total offspring) x 100%
autosomal chromosome: trait that is located on a NON-SEX chromosome (ex. Aa, RR)
autosomal dominant trait: present in every generation, not SEX-LINKED
x-linked recessive trait: not necessarily present in every generation, MORE MALES THAN FEMALES
the offspring inherits mitochondrial AND nuclear DNA from their MOTHER, while they ONLY inherit nuclear DNA from their FATHER
the larger the recombination frequency, the FURTHER the genes are
mitochondrial and chloroplast DNA are both inherited from the MOTHER
phenotypic plasticity: the ability of an organism to change its phenotype in response to environmental change
allows organisms to better fit a particular environment
euploid- contains chromosomes correctly organized into complete sets
aneuploid- missing one or more chromosomes
monosomy- 2n-1
trisomy- 2n+1
nondisjunction- when homologous chromosomes or sister chromatids fail to separate during meiosis I or II, or during mitosis
down syndrome- trisomy 21, 3 copies of chromosome 21
chromosomal rearrangement:
duplication- part is copied
deletion- part is removed
inversion- region is flipped around (opposite direction)
translocation- piece of one chromosome gets attached to another
reciprocal translocation- swapping of segments
horizontal gene transfer where genetic information is shared between organisms WITHOUTMATING