Students will learn about genes and how they affect important traits such as growth, reproduction, disease resistance, and behavior. Students will also discover the responsibilities of an animal geneticist.
Brahman Beef Cattle Photograph
Angus Beef Cattle Photograph
Brangus Beef Cattle Photograph
4-sided dice, 1 per student
Have You Any Wool? handout, 1 per student
Cattle Call handout, 1 per student
Essential Files (maps, charts, pictures, or documents)
offspring: the descendants of a person, animal, or plant
gene: a unit of heredity that is transferred from parent to offspring and determines some characteristic of the offspring
heredity: the transmission of genetic characters from parents to offspring
trait: observable, physical characteristic obtained through genetic inheritance
Did you know? (Ag Facts)
Geneticists study genes, heredity, and variations of living things. They could work as a researcher or a professor at a university.1
Biology, chemistry, and mathematics are important subjects for an animal geneticist to understand.2
Most animal geneticists have a master's degree or doctorate degree.2
Background Agricultural Connections
Interest Approach – Engagement
Brainstorm physical features, such as eye color and hair, which make students look different from each other.
Explain that these characteristics are called traits. A trait is a physical characteristic or feature, obvious and observable, which is inherited from one or more parent.
Ask the students if animals also possess traits. Brainstorm physical characteristics found in animals. Examples could include coat color or pattern, size of the animal, the presence or absence of horns, etc.
Explain that like people, animals also have specific traits that distinguish them. These traits are a result of their genetic makeup. At the completion of this lesson, students will:
consider how genes affect traits; and
discover the role of an animal geneticist.
Review the concept of probability and related terms such as chance, likely, unlikely, possible, and impossible with the students.
Instruct the students to raise their hand if they’ve ever been told they look like a family member. Allow a few students to share about their personal experience. Explain that traits are passed from parents to their children through DNA. The piece of DNA that carries the trait is called a gene. Clarify that traits may be dominant or recessive. A dominant trait is displayed if one or both parents carry the trait. A recessive trait is displayed only when both parents carry the trait.
Tell the students that traits are also passed on in the animal world. For example, livestock geneticists have been able to improve a breed’s traits through selective breeding programs. For example, breeders were able to cross Brahman beef cattle (show students the Brahman Beef Cattle photograph) and Angus beef cattle (show students Angus Beef Cattle photograph). Have students describe some of the obvious physical traits of each breed. Explain that the breed created from the two breeds is called a “Brangus” (show students the Brangus Beef Cattle photograph). Encourage students to identify the physical traits inherited from the Brahman and the Angus breeds. Explain that geneticists purposefully developed the breed to create a superior animal. Brahman cattle are tolerant to hot climates, and outstanding mothers. Angus cattle have excellent meat quality. The Brangus has the characteristics of both breeds.
Distribute the Have You Any Wool? handout to students and project a copy onto a large screen. Read the sheep’s genetic background aloud and define any unknown scientific terms. Explain that the Punnett square is a diagram that helps geneticists predict the outcome of breeding two animals.
Explain that the class is going to use the Punnett square to determine what color wool the sheep’s offspring will have. Dominant traits are expressed with a capital letter and recessive traits are expressed with a lowercase letter. If dominant and recessive traits are combined, the dominant trait will always overpower the recessive trait. Complete the Punnett square in front of the class while explaining the process.
Remind the students that probability is the likelihood that a particular event, or outcome, will occur. It is expressed as a fraction with the numerator being the total number of favorable outcomes and the denominator being the total number of possible outcomes. In this scenario, two quadrants have dominant genes for white wool and two quadrants have recessive genes for black wool; thus the lamb has a 2 out of 4 chance of inheriting white wool and a 2 out of 4 chance of inheriting black wool. Have every student roll a die to determine the breeding outcome. Instruct students to sketch a portrait of the lamb in the box provided at the bottom of the handout.
Tell the students that now that they know how to use the Punnett square to predict what animals will look like, they will practice being an animal geneticist by creating their own breed of cattle. Distribute the Cattle Call handout to students. Students will use the information provided about the bull and cow to determine the physical attributes of their offspring. Explain that the traits used as examples are not necessarily real cattle traits, but the traits will help students understand the main concepts of heredity. Instruct students to complete the Cattle Call handout. Review the handout and allow students to share their artwork.
Concept Elaboration and Evaluation
After conducting these activities, review and summarize the following key concepts:
An animal geneticist studies the genetic makeup of animals. They can help farmers and ranchers select and promote desirable traits in their animals. As animals improve, they are better able to provide meat, milk, and eggs to our diet.
The Punnett square is a tool used to predict the likelihood of an animal inheriting a specific trait.
The work of an animal geneticist benefits both producers (farmers and ranchers) and consumers.
Introduce genetics through an educational video on heredity. Check out the video “Heredity” on BrainPOPor search YouTube using the term “Punnett Square.”
Students work on the project individually, with a partner, in small groups, or as a class.
Students research actual phenotypes expressed in breeds of cattle. They create new variations of cattle by crossing actual breeds with the imaginary cattle featured in the Cattle Callhandout.
While leading students through the Have You Any Wool? handout, allow students time to think and respond to questions.
Throughout the lesson ELL students can be partnered with students that are proficient or advanced English speakers.
Students can define new terms like genes and alleles in their science journal or on a classroom word wall for future reference.
We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!
Instruct student groups to select a cattle breed to research. Have each group create a visual aid that illustrates the genetic history of their breed, including countries of origin, breed characteristics, and genetic selection over time.
Invite a local breeder to speak to the class about how they utilize genetics to improve their herd.
Have students research the educational background and skills required to be an animal geneticist.
Observe pictures of Hereford and Brahman cattle, and predict what a Braford would look like. Repeat with other breeds of Beef Cattle.
This lesson was funded in 2012 by the United States Department of Agriculture’s National Institute of Food and Agriculture through the Secondary Education, Two-Year Postsecondary Education, and Agriculture in the K-12 Classroom Challenge Grants Program (SPECA). Graphics submitted by California Foundation for Agriculture in the Classroom.
Executive Director: Judy Culbertson Illustrator: Erik Davison Layout and Design: Nina Danner
Mandi Bottoms & Sherrie Taylor Vann
California Foundation for Agriculture in the Classroom
Make sense of problems and persevere in solving them. Students start by explaining to themselves the meaning of a problem and looking for entry points to its solution. They analyze givens, constraints, relationships, and goals. They make conjectures about the form and meaning of the solution and plan a solution pathway rather than simply jumping into a solution attempt. They consider analogous problems, and try special cases and simpler forms of the original problem in order to gain insight into its solution. They monitor and evaluate their progress and change course if necessary. Students check their answers to problems using a different method, and they continually ask themselves, “Does this make sense?” They can understand the approaches of others to solving complex problems and identify correspondences between different approaches.
Reason abstractly and quantitatively. Students make sense of quantities and their relationships in problem situations. They bring two complementary abilities to bear on problems involving quantitative relationships: the ability to decontextualize—to abstract a given situation and represent it symbolically and manipulate the representing symbols as if they have a life of their own, without necessarily attending to their referents—and the ability to contextualize, to pause as needed during the manipulation process in order to probe into the referents for the symbols involved. Quantitative reasoning entails habits of creating a coherent representation of the problem at hand; considering the units involved; attending to the meaning of quantities, not just how to compute them; and knowing and flexibly using different properties of operations and objects.
Model with mathematics. Students can apply the mathematics they know to solve problems arising in everyday life, society, and the workplace. Students who can apply what they know are comfortable making assumptions and approximations to simplify a complicated situation, realizing that these may need revision later. They are able to identify important quantities in a practical situation and map their relationships using such tools as diagrams, two-way tables, graphs, flowcharts and formulas. They can analyze those relationships mathematically to draw conclusions.
3-LS3: Heredity: Inheritance and Variation of Traits