Dominant & Recessive Genetic Disorders (11.1) State Standard 2C. Using Mendel’s laws, explain the role of meiosis in reproductive variability. 2D. Describe the relationships between changes in DNA and potential appearance of new traits

Recessive Genetic Disorders Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Recessive Genetic Disorders A recessive trait is expressed when the individual is homozygous recessive for the trait. A person who is heterozygous is called a carrier.

Common among caucasians Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Cystic Fibrosis (Recessive) Common among caucasians 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. Treatment includes physical therapy, medication, & special diets.

A normal woman marries a man with cystic fibrosis A normal woman marries a man with cystic fibrosis. If they have children, what ratio will be totally normal? Explain.

Sun’s ultraviolet radiation is especially dangerous Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Albinism (Recessive) Caused by altered genes, resulting in the absence of the skin pigment melanin in hair, skin, and eyes White hair Very pale skin Pink pupils Sun’s ultraviolet radiation is especially dangerous

Albinism (Recessive) Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Albinism (Recessive)

An albino man marries a woman who is a carrier An albino man marries a woman who is a carrier. Create a Punnett Square to show the possibilities of their offspring. Include genotypic & phenotypic ratios.

Recessive disorder on chromosome 15 Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Tay-Sachs Disease (Recessive) Recessive disorder on chromosome 15 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. Occurs predominantly in Jews of Eastern European descent.

A man & woman who are both Tay Sachs carriers get married & decide to have children. What percent chance is there of them having a purebred normal baby? Use a Punnett Square to determine your answer.

Galactosemia (Recessive) Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Galactosemia (Recessive) Recessive genetic disorder characterized by the inability of the body to digest galactose. These people must avoid milk products. Milk products will cause numerous complications, including mental disability.

Dominant Genetic Disorders Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Dominant Genetic Disorders Because these disorders are caused by a dominant allele, they affect people who are homozygous dominant and people who are heterozygous.

Huntington’s disease affects the nervous system. Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Huntington’s Disease (Dominant) Huntington’s disease affects the nervous system. Occurs in 1 in 10,000 humans. Symptoms first appear between the ages of 30 & 50. Symptoms include loss of brain function, uncontrollable movements, and emotional disturbances.

Huntington’s Disease (Dominant) Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Huntington’s Disease (Dominant)

A woman who is hybrid for Huntington’s marries a man who is normal A woman who is hybrid for Huntington’s marries a man who is normal. What will be the genotypic & phenotypic ratios of their children?

Most common form of dwarfism. Adult height of about four feet. Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Achondroplasia (Dominant) Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short. Most common form of dwarfism. Adult height of about four feet. Normal life expectancy.

A man & woman who are both heterozygous for Achondroplasia have children. Can they have a normal child? Explain

Chapter 11 Complex Inheritance and Human Heredity

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

Label each part of the diagram below

Pedigree Challenge On your first day interning in the office of a human geneticist, a man with purple ears walks in. You questioned the man and wrote down the following family history. The man's mother and one of his sisters also had purple ears, but his father, his brother, and two other sisters had normal ears. The man and his normal-eared wife had seven children, including four boys and three girls. Two girls and two boys had purple ears. Draw the family pedigree and indicate what form of inheritance that the purple-ear trait most likely follows. (Is it dominant or a recessive passed trait?)

Chapter 11 Complex Inheritance and Human Heredity 11.1 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.

Identify the disease characterized by the absence of melanin. Chapter 11 Complex Inheritance and Human Heredity Chapter Diagnostic Questions Identify the disease characterized by the absence of melanin. albinism cystic fibrosis galactosemia Tay-Sachs A B C D CDQ 1

An individual with Tay-Sachs disease would be Chapter 11 Complex Inheritance and Human Heredity Chapter Diagnostic Questions An individual with Tay-Sachs disease would be identified by which symptom? excessive mucus production an enlarged liver a cherry-red spot on the back of the eye vision problems A B C D CDQ 2

Under what circumstances will a recessive trait be expressed? Chapter 11 Complex Inheritance and Human Heredity Chapter Diagnostic Questions Under what circumstances will a recessive trait be expressed? A recessive allele is passed on by both parents. One parent passes on the recessive allele. The individual is heterozygous for the trait. There is a mutation in the dominant gene. A B C D CDQ 3

Which is the genotype of a person who is Chapter 11 Complex Inheritance and Human Heredity 11.1 Formative Questions Which is the genotype of a person who is a carrier for a recessive genetic disorder? DD Dd dd dE A B C D FQ 2

Chapter 11 Complex Inheritance and Human Heredity 11.1 Formative Questions Albinism is a recessive condition. If an albino squirrel is born to parents that both have normal fur color, what can you conclude about the genotype of the parents? at least one parent is a carrier both parents are carriers both parents are homozygous recessive at least one parent is homozygous dominant A B C D FQ 3

Chapter 11 Complex Inheritance and Human Heredity 11.2 Formative Questions When a homozygous male animal with black fur is crossed with a homozygous female with white fur, they have offspring with gray fur. What type of inheritance does this represent? dosage compensation incomplete dominance multiple alleles sex-linked A B C D FQ 4

Of the 23 pairs of chromosomes in human Chapter 11 Complex Inheritance and Human Heredity 11.2 Formative Questions Of the 23 pairs of chromosomes in human cells, one pair is the _______. autosomes Barr bodies monosomes sex chromosomes A B C D FQ 5

Chapter 11 Complex Inheritance and Human Heredity Chapter Assessment Questions Use the figure to describe what the top horizontal line between numbers 1 and 2 indicates. 1 and 2 are siblings 1 and 2 are parents 1 and 2 are offspring 1 and 2 are carriers A B C D CAQ 1

If a genetic disorder is caused by a dominant Chapter 11 Complex Inheritance and Human Heredity Standardized Test Practice If a genetic disorder is caused by a dominant allele, what is the genotype of those who do not have the disorder? heterozygous homozygous dominant homozygous recessive A B C STP 1

RR Rr rr Standardized Test Practice Chapter 11 Complex Inheritance and Human Heredity Standardized Test Practice Analyze this pedigree showing the inheritance of a dominant genetic disorder. Which would be the genotype of the first generation father? A B C RR Rr rr STP 2