Chapter 4, Lesson 4: Chromosomes and Heredity

Flashcards from Chapter 1, Lesson 1 of McGraw Hill Anatomy and Physiology, Ninth Edition, by Kenneth S. Saladin.

Heredity

The transmission of genetic characteristics from parent to offspring

Karyotype

The chart of all 46 chromosomes by sides; shows 23 pairs of homologous chromosomes

Homologous chromosomes

Same chromosomes in pairs with one inherited from each parent

Autosomes

Chromosomes that look alike and carry the same genes

Sex chromosomes

Chromosomes that determine gender; men have one X and one Y chromosomes while women have homologous X chromosomes

Diploid

Any cell with 23 pairs of chromosomes; somatic (non-reproductive) cells are an example

Haploid

Cells with half as many chromosomes as somatic cells; ones in humans contain 23 unpaired chromosomes such as sperm and egg cells to restore regular pairing

Locus

The location of a particular gene on a chromosome

Allele

Different form of a particular gene; found at the same locus on homologous chromosomes

Dominant allele

An allele that expresses a protein in an individual

Recessive allele

An allele that does not express in an individual if it is paired with a dominant allele; only appears when recessive on both homologous chromosomes

Genotype

The allele an individual possesses for a particular gene; visualized using Punnet square

Phenotype

An observable trait

Genetic counselors

Perform genetic testing and advise couples on genetic diseases

Gene pool

The genetic makeup of the whole population

Multiple alleles

More than two allelic forms of a gene; seen in A, B, and O blood types

Codominance

Both alleles equally dominant and phenotypically expressed; seen in AB blood types

Incomplete dominance

Heterozygous individual shows phenotype between traits each allele would have produced alone

Polygenic inheritance

Genes at two or more loci contribute to a single trait

Pleiotropy

One gene produces multiple phenotypic effects

Sex-linked traits

Traits carried on the X or Y chromosomes; men inherit more than the other due to having only one X chromosome

Penetrance of allele

Percentage of population exhibiting expected phenotype; allele may not fully express in population or can be modified by the environment

Epigenetics

Field examining nongenetic changes that alter gene expression and can be passed to offspring

Carcinogens

Environmental cancer-causing agents that can damage DNA; they can be found in radiation, chemicals, and viruses and cause uncontrolled cell growth