Heredity

Use the text All in the Family by Dona Herweck Rice. Project on the whiteboard and read as a class. Then have students use text tools to identify key words and find examples of stated concepts.

Students plan, write, edit and revise a narrative story about an animal with certain inherited traits who is placed in an unusual new environment.

Visit the Where Did I Come From? lesson site. Students create a PowerPoint presentation showing heredity vocabulary words and appropriate illustrations for the words.

Count how many students in the class have a certain trait (eye color or hair color). Compare groups to see which trait is most common.

Using this heredity lesson, students make observations of traits and graph them. On Day 1, students count how many of each color are in the population, and make bar graphs. On Day 2, students graph their generation 2 data and compare to the first day's data.

Discuss variation in traits. Students measure and record the hand span from thumb to pinky (in centimeters) of ten classmates. Calculate the mean, median, and range of the distribution. Graph the data, labeling both axes.

Example of observations could include: leaves from the same kind of plant are the same shape but can differ in size, and a particular breed of dog looks like its parents but is not exactly the same. Individuals of the same kind of plant or animal are recognizable as similar but can also vary in many ways.

The environment also affects the traits that an organism develops. Some characteristics that result from individuals' interactions with the environment can range from diet to learning. Many characteristics involve both inheritance and the environment. Examples of the environment affecting a trait could include normally tall plants grown with insufficient water are stunted, and a pet dog that is given too much food and little exercise can become overweight.

Many characteristics of organisms are inherited from their parents. Patterns are the similarities and differences in traits shared between offspring and their parents, or among siblings. Different organisms vary in how they look and function because they have different inherited information.

Humans have the capacity to influence certain characteristics of organisms by selective breeding. One can choose desired parental traits determined by genes, which are then passed on to offspring. Emphasis is on synthesizing information from reliable sources about the influence of humans on genetic outcomes in artificial selection (such as genetic modification, animal husbandry, gene therapy) and, on the impacts these technologies have on society as well as the technologies leading to these scientific discoveries.

Emphasis is on using concepts of natural selection like overproduction of offspring, passage of time, variation in a population, selection of favorable traits, and heritability of traits. Traits that support successful survival and reproduction become more common, while those that do not become less common.

Variations of inherited traits between parent and offspring arise from genetic differences that result from the subset of chromosomes (and therefore genes) inherited. In sexually reproducing organisms, each parent contributes half of the genes acquired (at random) by the offspring. Individuals have two of each chromosome and hence two alleles of each gene, one acquired from each parent. These versions may be identical or may differ from each other. Emphasis is on using models such as Punnett squares, diagrams, and simulations to describe the cause and effect relationship of gene transmission from parents to offspring and resulting genetic variation.

Genes are located chiefly in the chromosomes of the cells, with each chromosome pair containing two variants of each of many distinct genes. Each distinct gene chiefly controls the production of specific proteins, which in turns affects the traits of the individual. In addition to variations that arise from sexual reproduction, genetic information can be altered because of mutations. Though rare, changes (mutations) to genes can result in changes to the structure and function of the proteins and the organism and thereby change traits. Some changes are beneficial, others harmful, and some neutral to the organism. Emphasis is on conceptual understanding that changes in genetic material may result in making different proteins.