Studied by 0 people
Inheritance – definitions and terms • Mendel and his pea plants • Punnett squares – Monohybrid – Dihybrid • Linkage • Incomplete dominance, codominance, pleiotropic traits • Sex linked traits, X inactivation • Diseases
Inheritance
The process in which genetic material is passed from parents to their offspring.
Genes
DNA segments that serve as the key functional units in hereditary transmission.
Allele
Different forms of a gene
Homozygous
Having two identical alleles for a particular gene (GG or gg)
Heterozygous
An organism that has two different alleles for a trait (Gg)
dominant allele
An allele whose trait always shows up in the organism when the allele is present.
recessive allele
An allele that is masked when a dominant allele is present
polygenic inheritance
An additive effect of two or more genes on a single phenotypic character.
Pleotropic
one gene affects many characteristics
P generation
Parental generation, the first two individuals that mate in a genetic cross True breeding parents
F1 generation
hybrid offspring of the P generation
F2 generation
Offspring resulting from interbreeding of the hybrid F1 generation.
carriers
heterozygous individuals who carry the recessive allele but are phenotypically normal
Phenotype
An organism's physical appearance, or visible traits.
Genotype
genetic makeup of an organism
monohybrid cross
A cross between individuals that involves one pair of contrasting traits
Genotypic ratio
the ratio of the genotypes that appear in offspring 1:2:1
Phenotypic ratio
the ratio of phenotypes produced by a cross 3:1
Law of Segregation
Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete
sex-linked alleles
-Y chromosome does not carry alleles for X-linked traits -Males always receive X from female parent, Y from male parent
independent assortment
One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes
Incomplete dominance
A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.
Codominance
situation in which both alleles of a gene contribute to the phenotype of the organism
Pleiotropy
The ability of a single gene to have multiple effects.
Epistasis
A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited.
A=aa
Ao
B=BB
Bo
AB
Ab
O
OO
A=B>O
O is able to go into each type
X inactivation
one of two X chromosomes is randomly inactivated and remains coiled as a Barr body
