Single Gene Inheritance I & Ii (Foundations Final Exam)

Front 1

segregation

Back 1

two alleles for each trait separate during gamete formation, and then unite at random, one from each parent, at fertilization

Front 2

independent assortment

Back 2

during gamete formation, different pairs of alleles segregate independently of each other

Front 3

inbreeding

Back 3

occurs when both members of a reproducing couple have a common ancestor
- increases the chances of a rare recessive allele appearing in homozygous condition
expected in:
geographically isolated demes
socially isolated demes

Front 4

locus

Back 4

position of a gene on a chromosome

Front 5

proband

Back 5

the individual through whom the genetic disorder is first ascertained

Front 6

genetic heterogeneity

Back 6

term used to describe the phenomenon where the same phenotype is caused by different genotypic abnormalities

Front 7

allelic heterogeneity

Back 7

occurs when abnormal phenotype is caused by different mutations at the same locus

Front 8

locus, or nonallelic, heterogeneity

Back 8

used to describe the situation where a particular phenotype can be the result of mutations at 2 or more separate loci

Front 9

autosomal dominant disorders

Back 9

- vertical transmision
- all affected people have an affected parent
- 1/2 of offspring of affected person are affected
- no gender bias
examples: marfan's, neurofibromatosis I, renal cysts

Front 10

expressivity

Back 10

- the degree to which phenotype reflects genotype
- variable expressivity
- manifestations in people with the same genotype
- most striking in autosomal dominant

Front 11

penetrance

Back 11

- all or none phenomenon
- person with abnormal genotype does not manifest
- # of person with disorder / # of persons with abnormal genotype
- age dependent penetrance

Front 12

pleiotropy

Back 12

mutant genes usually produce their effects on multiple organ systems and functions

Front 13

autosomal recessive inheritance

Back 13

- horizontal inheritance
- may affect numerous members of a sibship
- parents may be unaffected carriers
- no gender bias

Front 14

dosage compensation

Back 14

- X-linked genes are expressed at the same level in females
- results from X inactivation
- may result in variable expression

Front 15

X-linked recessive inheritance

Back 15

- no male-to-male transmission
- carrier females unaffected
- 1/2 of sons of female carriers affected

Front 16

X-linked dominant inheritance

Back 16

- no male-to-male transmission
- carrier females variably affected
- 1/2 of offspring of female carriers affected