AP Bio 5-4 vocab terms; Heredity

Pedigree

A diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations.

Multifactorial

Referring to a phenotypic character that is influenced by multiple genes and environmental factors.

Polygenic Inheritance

An additive effect of two or more genes on a single phenotypic character.

True breeding

Referring to organisms that produce offspring of the same variety over many generations of self-pollination.

Sickle-cell Disease

A recessively inherited human blood disorder in which a single nucleotide change in the B-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms in afflicted individuals.

Character

An observable heritable feature that may vary among individuals.

Incomplete dominance

The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.

Deletion

(1)A deficiency in a chromosome, resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene.

Linkage map

A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes.

Non disjunction

an error in meiosis or mitosis in which members of a pair of homologous chromosomes or sister chromatids fail to separate properly from each other.

Map units

A unit of measurement of the distance between genes. One map unit is equivalent to a 1% recombination frequency.

Chromosome theory of inheritance

A basic principle in biology stating that genes are located at specific positions (loci) on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

Barr body

A dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome.

Parental types

An offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotype itself.

Trisomic

Referring to a diploid that has three copies of a particular chromosome instead of the normal two.

Wild type

The phenotype most commonly observed in natural populations; also refers to the individual with that phenotype.

Sex-linked gene

A gene located on either sex chromosome. Most sex-linked genes are on the X chromosome and show distinctive patterns of inheritance; there are very few genes on the Y chromosome.

Hemophilia

A human genetic disease caused by a sex-linked recessive allele, resulting in the absence of one or more blood-clotting proteins; characterized by excessive bleeding following injury.

Inversion

An aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated.

Recombinant types

An offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself.