Vocabulary Vocabulary ReviewReview

Ch 12 Ch 12

Inheritance Inheritance Patterns and Patterns and

Human GeneticsHuman Genetics

One of the pair of chromosomes that determine the sex

of an individual

Sex Chromosome

Any chromosome that is not a sex

chromosome

Autosome

A trait that is determined by a gene found on one of the sex chromosomes,

such as the X chromosome or the Y

chromosome in humans

Sex-linked Trait

One of a pair of genes that tend to

be inherited together

Linked Gene

A diagram of gene positions on a chromosome

Chromosome map

In chromosome mapping, an

increment of 1 percent in the frequency of crossing-over

Map unit

Mutation that occurs in an organism’s gametes

Germ-cell mutation

A mutation that occurs in a body

cell

Somatic-cell mutation

A gene or chromosomal mutation

that influences the development of an

organism in such a way that the organism

cannot survive

Lethal mutation

The loss of a part of DNA from a chromosome

Deletion

A reversal in the order of the

genes, or of a chromosome

segment, within a chromosome

Inversion

The movement of a segment of DNA from one chromosome to another, which results in a change

in the position of the segment; also the

movement of soluble nutrients from one part of

a plant to another

Translocation

The failure of homologous

chromosomes to separate during

meiosis I or the failure of sister chromatids to

separate during mitosis or meiosis II

Nondisjunction

A mutation in which only one nucleotide or

nitrogenous base in a gene is

changed

Point mutation

A mutation in which a nucleotide or a codon in DNA is replaced with a

different nucleotide

Substitution

A mutation, such as the insertion or deletion of a

nucleotide in a coding sequence, that results in

the misreading of the code during translation because of a change in

the reading frame

Frameshift mutation

A mutation in which one or more

nucleotides are added to a gene

Insertion mutation

A diagram that shows the

occurrence of a genetic trait in

several generations of a

family

Pedigree

In genetics, an individual who has

one copy of a recessive autosomal

allele that causes disease in the homozygous

conditionCarrier

An inherited disease or

disorder that is caused by a

mutation in a gene or by a

chromosomal defectGenetic disorder

Describes a characteristic that

is influenced by many genes

Polygenic

A character such as skin color that

is influenced strongly by both genes and the environment

Complex character

More than two alleles (versions of

the gene) for a genetic trait

Multiple allele

A condition in which both alleles for a gene are fully

expressed

Codominance

A condition in which a trait in an individual is

intermediate between the phenotype of the

individual’s two parents because the dominant

allele is unable to express itself fully

Incomplete dominance

An autosomal trait that is influenced by the presence of male or female sex

hormones

Sex-influenced trait

A rare hereditary disease of the brain

characterized by involuntary

movements of the limbs or face,

decreasing mental abilities, and eventual

deathHuntington’s disease

A procedure used in fetal diagnosis in which amniotic fluid is removed

from the uterus of the pregnant

womanAmniocentesis

A procedure in which the

chorionic villi are analyzed to

diagnose fetal genotypes

Chorionic villi sampling

The process of testing and informing potential

parents about their genetic makeup and the likelihood that they will

have offspring with genetic defects or

hereditary diseases

Genetic counseling

A technique that places a gene into a cell to correct a hereditary disease or to improve the

genome

Gene therapy