LZHS H Bio I Topic 8 Inheritance of Traits

Chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins.

Somatic Cells

any cell of a living organism other than the reproductive cells, diploid (2n)

Gametes

a mature haploid (n) male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

Independent Assortment

the random distribution of the pairs of genes on different chromosomes to the gametes

Meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

XX Chromosomes

female sex chromosomes

XY Chromosomes

male sex chromosomes

Mutation

A change in a gene or chromosome.

Deletion

removes a chromosomal segment

Insertion

A mutation involving the addition of one or more nucleotide pairs to a gene.

Substitution

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

Germ Mutation

mutation or mistake in a germ or reproductive cell, can be passed to offspring

Somatic Cell Mutation

change within cells of the body, cannot be transmitted

Environmental Mutations

damage to DNA and chromosomes caused by environmental factors

Environmental Factors

Those "nonbiological" factors that are involved in a person's surroundings such as the nature of the person's parents, the person's friends, and the person's behavioral choices.

Pollutant

A material found in air, water, or soil that is harmful to humans or other organisms, can cause an environmental mutation

Crossing Over

exchange of genetic material between homologous chromosomes during prophase I of meiosis

Genetic Variation in Meiosis

Results in cells that are genetically different as the result of crossing over and independent assortment

Nondisjunction in Meiosis I

Homologous chromosomes do not separate properly (all cells abnormal); usually occurs during Anaphase 1

Trisomy

3 copies of a chromosome; occurs when chromosomes fail to separate properly