Table of Contents Human Inheritance Human Genetic Disorders Advances in Genetics

Patterns of Human Inheritance Single genes with two alleles Ex: widow’s pick Figure 2 Punnett Square

Patterns of Human Inheritance Single genes with multiple alleles Ex: Inheritance of Blood Type Blood type is determined by a single gene with three alleles.fig3/146

Patterns of Human Inheritance Traits controlled by many genes Ex: human height Discovery activity/p144

The Sex Chromosomes - Human Inheritance The sex chromosomes carry genes that determine whether a person is male or female. They also carry genes that determine other traits.

The Sex chromosomes Sex-linked genes- genes on the X and Y chromosomes not always the same Can have dominant and recessive alleles Because males have only one X chromosome, male are more likely to have a sex linked trait that is controlled by recessive alleles. Female -2X Male 1X, 1Y

Colorblindness Punnett Square - Human Inheritance Colorblindness Punnett Square Red-green colorblindness is a sex-linked trait. A girl who receives only one recessive allele (written Xc) for red-green colorblindness will not have the trait. However, a boy who receives one recessive allele will be colorblind.

Identifying Main Ideas - Human Inheritance Identifying Main Ideas As you read the section “Patterns of Human Inheritance,” write the main idea in a graphic organizer. Then write three supporting details that further explain the main idea. Main Idea Human traits are controlled by single genes with two alleles, single genes with multiple alleles, and multiple genes. Detail Detail Detail Human traits controlled by single genes with two alleles have two distinctly different phenotypes. Though a single gene can have multiple alleles, a person can carry only two of these alleles. Multiple genes that control a trait act together to produce a single trait with a large number of phenotypes.

The effect of environment Many of a person’s characteristics are determined by an interaction between genes and the environment

Click the SciLinks button for links on genetics. - Human Inheritance Links on Genetics Click the SciLinks button for links on genetics.

End of Section: Human Inheritance

Human Genetic Disorders Genetic disorder- abnormal condition that a person inherits through genes or chromosomes Causes: Mutations in the DNA of genes Changes in the structure of chromosoms Changes in the number of chromosomes

Human Genetic Disorders Cystic Fibrosis- body produces abnormally thick mucus in the lungs or intestines Cause by a recessive allele on one chromosome as a result of a mutation in which three bases are removed from a DNA molecule

Human Genetic Disorders Sickle –Cell Disease Affects hemoglobin, a protein in the red blood cells that carries oxygen; cells clog blood vessels The allele is codominant with normal allele A person with two sickle cell alleles will have the disease

Human Genetic Disorders Hemophilia Person’s blood clots very slowly or nor at all Caused by a recessive allele on the X chromosome Sex-linked disorder/occurs more in male than in females

Human Genetic Disorders Down Syndrome A person’s cell have an extra copy of chromosome 21 ( 3 chromosomes) Occurs when chromosomes fail to separate properly during meiosis Effect: some degree of mental retardation; heart defects

A Pedigree - Human Genetic Disorders A pedigree is a chart or “family tree” that tracks which members of a family have a particular trait.

A Hemophilia Pedigree - Human Genetic Disorders The pedigree shows the inheritance of hemophilia, a sex-linked disorder in a family.

Managing Genetic Disorders Karyotypes- picture of all the chromosomes in a cell Genetic counseling- understand the chances of having a child with a particular genetic disorder Dealing with genetic disorders

Pedigree Activity - Human Genetic Disorders Click the Active Art button to open a browser window and access Active Art about pedigrees.

Comparing and Contrasting - Human Genetic Disorders Comparing and Contrasting As you read, compare and contrast the types of genetic disorders by completing a table like the one below. Disorder Description Cause Cystic fibrosis Body produces abnormally thick mucus. Recessive allele due to removal of three DNA bases Sickle-cell disease Red blood cells are sickle-shaped and have reduced ability to hold oxygen. Codominant allele Hemophilia Blood clots slowly or not at all. Recessive allele on X chromosome Down Syndrome Mental retardation and heart defects An extra copy of chromosome 21

Click the Video button to watch a movie about sickle-cell disease. - Human Genetic Disorders Sickle-Cell Disease Click the Video button to watch a movie about sickle-cell disease.

End of Section: Human Genetic Disorders

Advances in Genetics Selective Breeding: selecting organisms with desired traits to be parents of the next generation Inbreeding: crossing two individuals that have the similar Characteristics Hybridization: crossing two genetically different individuals; the offspring will have the best traits from both parents

Changing Rice Production - Advances in Genetics Changing Rice Production The graph shows how worldwide rice production changed between 1965 and 2000. New, hybrid varieties of rice plants are one factor that has affected the amount of rice produced.

Changing Rice Production - Advances in Genetics Changing Rice Production Reading Graphs: According to the graph, how did rice production change between 1965 and 2000? Rice production increased.

Changing Rice Production - Advances in Genetics Changing Rice Production Reading Graphs: How many metric tons of rice per hectare were produced in 1965? How many were produced in 2000? 2 in 1965; 4 in 2000

Changing Rice Production - Advances in Genetics Changing Rice Production Calculating: Calculate the approximate difference between rice production in 1965 and 2000. 2 metric tons/hectare

Changing Rice Production - Advances in Genetics Changing Rice Production Developing Hypotheses: What factors besides new varieties of plants might help account for the difference in rice production between 1965 and 2000? Possible answer: fertilizers and improved harvesting methods

Cloning Organism that have the exact genes as the organism from which it was produced Is cloning ethical?

Genetic Engineering - Advances in Genetics Scientists use genetic engineering to create bacterial cells that produce important human proteins such as insulin.

Asking Questions - Advances in Genetics Before you read, preview the red headings. In a graphic organizer like the one below, ask a question for each heading. As you read, write answers to your questions. Questions Answers What is selective breeding? Selective breeding is the process of selecting organisms with desired traits to be parents of the next generation. Why are organisms cloned? To produce offspring with desired traits What is genetic engineering? A process in which genes from one organism are transferred into the DNA of another organism What advance has helped us learn about human genetics? The Human Genome Project

Links on Genetic Engineering - Advances in Genetics Links on Genetic Engineering Click the SciLinks button for links on genetic engineering.

Click the Video button to watch a movie about selective breeding. - Advances in Genetics Selective Breeding Click the Video button to watch a movie about selective breeding.

End of Section: Advances in Genetics

Graphic Organizer Human traits controlled by such as Multiple alleles Sex-linked genes Single genes Many genes Widow's peak Blood type Height Colorblindness

End of Section: Graphic Organizer