Click on a lesson name to select. Section 1: Basic Patterns of Human Inheritance Section 2: Complex Patterns of Inheritance Section 3: Chromosomes and Human Heredity Chapter 11 Complex Inheritance and Human Heredity AHSGE CONTENT STANDARD #7: Apply Mendel’s laws to determine phenotypic and genotypic probabilities of offspring.

Basic Patterns of Human Inheritance (Section 11.1) MAIN IDEA: The inheritance of a trait over several generations can be shown in a pedigree.

Click on a lesson name to select Basic Patterns of Human Inheritance Objectives Analyze genetic patterns to determine dominant or recessive inheritance patterns. Summarize examples of dominant and recessive disorders. Construct human pedigrees from genetic information.

Click on a lesson name to select. Review Vocabulary genes – segments of DNA that control the production of proteins. dominant – Mendel’s name for a specific trait that appeared in the F1 generation. (Webster’s: commanding, controlling, or prevailing over all others) recessive – Mendel’s name for a specific trait hidden or masked in the F1 generation.

Click on a lesson name to select. New Vocabulary carrier pedigree

11.1 Basic Patterns of Human Inheritance Complex Inheritance and Human Heredity Chapter 11 Recessive Genetic Disorders  A recessive trait is expressed when the individual is homozygous recessive for the trait.

Complex Inheritance and Human Heredity 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 Basic Patterns of Human Inheritance Chapter 11

Cystic Fibrosis (recessive genetic disorder)

Approximately 1 in 20 people are carriers of the Cystic Fibrosis gene and when two carriers parent a child there is a 1 in 4 chance of the child being born with Cystic Fibrosis.

Complex Inheritance and Human Heredity 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 11.1 Basic Patterns of Human Inheritance Chapter 11

Albinism (recessive genetic disorder)

Complex Inheritance and Human Heredity 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 Basic Patterns of Human Inheritance Chapter 11

Tay-Sachs Disease (recessive genetic disorder) Affects 1 in 2500 people in the United States. (affects people of Jewish descent)

Tay-Sachs Disease (recessive genetic disorder) Tay-Sachs Disease is often identified by a cherry-red spot on the back of the eye.

Complex Inheritance and Human Heredity Galactosemia  Recessive genetic disorder characterized by the inability of the body to digest galactose Basic Patterns of Human Inheritance Chapter 11

Galactosemia (recessive genetic disorder)

Complex Inheritance and Human Heredity 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 Basic Patterns of Human Inheritance Chapter 11

Achondroplasia (DOMINANT genetic disorder) How is achondroplasia inherited? People with achondroplasia may pass on the condition to their children. If one parent is affected, each child has a one- in-two chance of having achondroplasia, and a one-in- two chance of being average height. Those born with achondroplasia may pass the condition on to their own children, while those of average height will not.

Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity Chapter 11

Complex Inheritance and Human Heredity Pedigrees  A diagram that traces the inheritance of a particular trait through several generations 11.1 Basic Patterns of Human Inheritance Chapter 11

Complex Inheritance and Human Heredity 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 Basic Patterns of Human Inheritance Chapter 11

Section 11.1 Summary Genetic disorders can be caused by dominant or recessive alleles. Cystic fibrosis is a genetic disorder that affects mucus and sweat secretions. Individuals with albinism do not have melanin in their skin, hair, and eyes. Huntington’s disease affects the nervous system. Achondroplasia sometimes is called dwarfism. Pedigrees are used to study human inheritance patterns.

Complex Patterns of Inheritance (Section 11.2) MAIN IDEA: Complex inheritance of traits does not follow inheritance patterns described by Mendel.

Complex Patterns of Inheritance (Section 11.2) Objectives Distinguish between various complex inheritance patterns. Analyze sex-linked and sex-limited inheritance patterns. Explain how the environment can influence the phenotype of an organism.

Review Vocabulary gamete – a mature sex cell (sperm or egg) with haploid number of chromosomes.

New Vocabulary incomplete dominance codominance multiple alleles epistasis sex chromosome autosome sex-linked trait polygenic trait

11.2 Complex Patterns of Inheritance Complex Inheritance and Human Heredity Incomplete Dominance  The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes. Chapter 11

Complex Inheritance and Human Heredity Codominance  Both alleles are expressed in the heterozygous condition Complex Patterns of Inheritance Chapter 11 Incomplete Dominance …from a different perspective

Complex Inheritance and Human Heredity Sickle-cell Disease  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 Normal red blood cell 7766x 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Multiple Alleles  Blood groups in humans  ABO blood groups have three forms of alleles Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Coat Color of Rabbits  Multiple alleles can demonstrate a hierarchy of dominance.  In rabbits, four alleles code for coat color: C, c ch, c h, and c Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Coat Color of Rabbits Light gray Dark gray Himalayan Albino Chinchilla 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Epistasis  Variety is the result of one allele hiding the effects of another allele. No dark pigment present in fur Dark pigment present in fur eebb eeB_ E_bbE_B_ 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Sex Determination  Sex chromosomes determine an individual’s gender Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity 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.  Chromosome inactivation  Barr bodies 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Sex-Linked Traits  Genes located on the X chromosome  Red-green color blindness  Hemophilia 11.2 Complex Patterns of Inheritance Chapter 11 Sex-Linked Traits

Complex Inheritance and Human Heredity Polygenic Traits  Polygenic traits arise from the interaction of multiple pairs of genes Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity Environmental Influences  Environmental factors  Diet and exercise  Sunlight and water  Temperature 11.2 Complex Patterns of Inheritance Chapter 11

Complex Inheritance and Human Heredity 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 Complex Patterns of Inheritance Chapter 11

Section 11.2 Summary Some traits are inherited through complex inheritance patterns, such as incomplete dominance, codominance, and multiple alleles. Gender is determined by X and Y chromosomes. Some traits are linked to the X chromosome. Polygenic traits involve more than one pair of alleles. Both genes and environment influence an organism’s phenotype. Studies of inheritance patterns of large families and twins give insight into complex human inheritance.

Chromosomes and Human Heredity (Section 11.3) MAIN IDEA: Chromosomes can be studied using karyotypes.

Chromosomes and Human Heredity (Section 11.3) Objectives Distinguish normal karyotypes from those with abnormal numbers. Define and describe the role of telomeres. Relate the effect of nondisjunction to Down syndrome and other abnormal chromosome numbers. Assess the benefits and risks of diagnostic fetal testing.

Click on a lesson name to select. Review Vocabulary mitosis – a process in the nucleus of a dividing cell, including prophase, metaphase, anaphase, and telophase (PMAT!!!).

Click on a lesson name to select. New Vocabulary karyotype telomere nondisjunction

 Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size Chromosomes and Human Heredity Complex Inheritance and Human Heredity Karyotype Studies  Images of chromosomes stained during metaphase  Chromosomes are arranged in decreasing size to produce a micrograph. Chapter 11

Complex Inheritance and Human Heredity Telomeres  Telomere caps consist of DNA associated with proteins.  Serves a protective function for the structure of the chromosome Chromosomes and Human Heredity Chapter 11

Complex Inheritance and Human Heredity Nondisjunction  cell division during which sister chromatids fail to separate properly  Down syndrome 11.3 Chromosomes and Human Heredity Chapter 11 Visualizing Nondisjunction

Complex Inheritance and Human Heredity Chapter 11

Section 11.3 Summary Karyotypes are micrographs of chromosomes. Chromosomes terminate in a cap called a telomere. Nondisjunction results in gametes with an abnormal number of chromosomes. Down syndrome is a result of nondisjunction. Tests for assessing the possibility of genetic and chromosomal disorders are available.