Complex Inheritance and Human Heredity Section 1 Basic

Complex Inheritance and Human Heredity Section 1: Basic Patterns of Human Inheritance Section 2: Complex Patterns of Inheritance Section 3: Chromosomes and Human Heredity Click on a lesson name to select.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Recessive Genetic Disorders § A recessive trait is expressed when the individual is homozygous recessive for the trait.

Section 1 Complex Inheritance and Human Heredity Table 11. 2 Recessive Genetic Disorders in Humans

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Cystic Fibrosis § Affects the mucus-producing glands, digestive enzymes, and sweat glands § Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat. § Without sufficient chloride ions in the cells, a thick mucus is secreted.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Albinism § Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes § White hair § Very pale skin § Pink pupils

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Tay-Sachs Disease § Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides § Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Galactosemia § Recessive genetic disorder characterized by the inability of the body to digest galactose. § Results in: § a lack of energy (lethargy), § a failure to gain weight and grow as expected § yellowing of the skin and whites of the eyes (jaundice), § liver damage, § abnormal bleeding.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Dominant Genetic Disorders § Huntington’s disease affects the nervous system. § Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance

Section 1 Complex Inheritance and Human Heredity

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Pedigrees § A diagram that traces the inheritance of a particular trait through several generations

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Inferring Genotypes § Knowing physical traits can determine what genes an individual is most likely to have. Predicting Disorders § Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Incomplete Dominance § The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Codominance § Both alleles are expressed in the heterozygous condition. § Sickle-cell disease is one example.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sickle-cell Disease Normal red blood cell § Changes in hemoglobin cause red blood cells to change to a sickle shape. § People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell 7766 x

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Multiple Alleles § Blood groups in humans § ABO blood groups have three forms of alleles.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Coat Color of Rabbits § Multiple alleles can demonstrate a hierarchy of dominance. § In rabbits, four alleles code for coat color: C, cch, and c.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Epistasis § Variety is the result of one allele hiding the effects of another allele.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sex Determination § Sex chromosomes determine an individual’s gender.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Dosage Compensation § The X chromosome carries a variety of genes that are necessary for the development of both females and males. § The Y chromosome mainly has genes that relate to the development of male characteristics. § In females, one X chromosome is inactivated in each cell. The inactivated X chromosome is visible in stained cells as a Barr body.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sex-Linked Traits § Genes located on the X chromosome § Red-green color blindness § Hemophilia Sex-Linked Traits

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Polygenic Traits § Polygenic traits arise from the interaction of multiple pairs of genes.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Environmental Influences § Environmental factors influence an organism’s phenotype § Diet and exercise § Sunlight and water § Temperature

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Twin Studies § Helps scientists separate genetic contributions from environmental contributions § Traits that appear frequently in identical twins are at least partially controlled by heredity. § Traits expressed differently in identical twins are strongly influenced by environment.

Section 3 Complex Inheritance and Human Heredity Chromosomes and Human Heredity Karyotype Studies § Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size. § Images of chromosomes stained during metaphase § Chromosomes are arranged in decreasing size to produce a micrograph.

Section 3 Complex Inheritance and Human Heredity Chromosomes and Human Heredity Telomeres § Telomere caps consist of DNA associated with proteins. § Serves a protective function for the structure of the chromosome

Section 3 Complex Inheritance and Human Heredity Chromosomes and Human Heredity Nondisjunction § Cell division during which sister chromatids fail to separate properly § Down syndrome, also called trisomy 21