Genetic Disorders

Recessive Genetic Disorders

Your physical characteristics are not the only traits that can be inherited from your parents.  Many genetic disorders are inherited as either dominant or recessive alleles.  Changes in the DNA cause defects in particular genes, which have deleterious effects in the offspring. Recessive disorders, such as phenylketonuria, Tay-Sachs disease, and cystic fibrosis are all caused by an offspring inheriting both defect alleles from their parents. In this interactivity, learn about these three recessive genetic disorders. Click the player button to begin.

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Dominant Genetic Disorders

A person only needs one defective allele to inherit a dominant genetic disorder. Most people with dominant genetic disorders are heterozygous for the trait because homozygous dominant inheritance generally results in miscarriage during pregnancy. In this interactivity, explore two different dominant genetic disorders. Click the player button to begin.

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Chromosome Disorders

The study of inheritance is not limited to just examining an organism’s genes. Whole chromosomes can be studied to determine if there are any inherited genetic disorders. In order to study chromosomes, geneticists study a karyotype. A karyotype is the arrangement of chromosomes in the cell nuclei of an organism or species. The sex chromosomes make up the twenty-third pair. Karyotypes are produced from cells that are cultured in a laboratory setting and stained to reveal identifying bands on homologous chromosomes. The chromosomes are then arranged from increasing to decreasing size. The sex chromosomes make up the twenty-third pair.

Nondisjunction occurs when chromosomes do not separate correctly during meiosis, which causes the newly formed cells to have the wrong number of chromosomes. Either homologous chromosomes do not separate in meiosis I, or sister chromatids do not separate during meiosis II. The end result is gametes that have only one copy of a particular chromosome, called monosomy, or that have three of the same type of chromosome, called trisomy. In this interactivity, learn more about some genetic disorders caused by chromosomal issues.

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Genetic Disorders Review

Now that you investigated genetic disorders, review your knowledge. In this non-graded interactivity, read each statement and determine if it is true of false. Click the player button to get started.