Table of Contents • Human Inheritance • Human Genetic Disorders • Advances in Genetics
- Human Inheritance Inheritance of Blood Type • Blood type is determined by a single gene with three alleles. This chart shows which combinations of alleles result in each blood type.
- Human Inheritance The Sex Chromosomes • The sex chromosomes carry genes that determine whether a person is male or female. They also carry genes that determine other traits.
- 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.
- 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.
- Human Inheritance Links on Genetics • Click the SciLinks button for links on genetics.
- Human Genetic Disorders A Pedigree • A pedigree is a chart or “family tree” that tracks which members of a family have a particular trait.
- Human Genetic Disorders A Hemophilia Pedigree • The pedigree shows the inheritance of hemophilia, a sex-linked disorder in a family.
- Human Genetic Disorders Pedigree Activity • Click the Active Art button to open a browser window and access Active Art about pedigrees.
Cystic fibrosis Body produces abnormally thick mucus. Recessive allele due to removal of three DNA bases Red blood cells are sickle-shaped and have reduced ability to hold oxygen. Sickle-cell disease 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 - 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
- Human Genetic Disorders Sickle-Cell Disease • Click the Video button to watch a movie aboutsickle-cell disease.
- 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.
Rice production increased. Reading Graphs: According to the graph, how did rice production change between 1965 and 2000? - Advances in Genetics Changing Rice Production
2 in 1965; 4 in 2000 Reading Graphs: How many metric tons of rice per hectare were produced in 1965? How many were produced in 2000? - Advances in Genetics Changing Rice Production
2 metric tons/hectare Calculating: Calculate the approximate difference between rice production in 1965 and 2000. - Advances in Genetics Changing Rice Production
Possible answer: fertilizers and improved harvesting methods Developing Hypotheses: What factors besides new varieties of plants might help account for the difference in rice production between 1965 and 2000? - Advances in Genetics Changing Rice Production
- Advances in Genetics Genetic Engineering • Scientists use genetic engineering to create bacterial cells that produce important human proteins such as insulin.
- Advances in Genetics Asking Questions • 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
- Advances in Genetics Links on Genetic Engineering • Click the SciLinks button for links on genetic engineering.
- Advances in Genetics Selective Breeding • Click the Video button to watch a movie aboutselective breeding.
Humantraits controlled by such as such as such as such as Graphic Organizer Sex-linked genes Multiple alleles Single genes Many genes Widow's peak Blood type Height Colorblindness