Note to teacher: Students will be working individually and in groups of 3 for the activities today.
Script: Welcome to the Ingenia Biology Lab. Today you will be biology apprentices and you will be participating in the study of genetic traits and how they are passed along from generation to generation. We will begin by exploring observable traits. Traits are observable characteristics that are passed down from parent to child. An individual will have many traits they share in common with others. An individual’s overall combination of traits makes them unique. Some traits are more common in a population than others. Let’s explore the traits we have represented in our classroom.
Students take an inventory of their own easily-observable genetic traits and compare those inventories with other students in their groups and also in the class as a whole. Ask students to complete the Inventory of My Traits worksheet making note of any observable traits they have.
Use the slides to go through some of the observable traits and demonstrate to students as needed. The traits are:
Earlobe Attachment: If earlobes hang free, they are detached. If they connect directly to the sides of the head, they are attached. Earlobe attachment is a continuous trait: while most earlobes can be neatly categorized as attached or unattached, some are in-between.
Tongue Rolling: Some people can curl up the sides of their tongue to form a tube shape. In 1940, Alfred Sturtevant observed that about 70% of people of European ancestry could roll their tongues and the remaining 30% could not. However, as Sturtevant observed, people can learn to roll their tongue as they get older, suggesting that environmental factors—not just genes—influence the trait.
Dimples: Dimples are small, natural indentations on the cheeks. They can appear on one or both sides, and they often change with age. Some people are born with dimples that disappear when they’re adults; others develop dimples later in childhood. Dimples are highly heritable, meaning that people who have dimples tend to have children with dimples—but not always.
Handedness: Handedness describes our preference for using either our left or right hand for activities such as writing and throwing a ball. Overall, about 10% of people are left-handed, but the number varies among cultures from 0.5% to 24%
Freckles: Freckles are small, concentrated spots of a skin pigment called melanin. Most fair-skinned, red-haired people have them. Freckles show a dominant inheritance pattern: parents who have freckles tend to have children with freckles.
Curly Hair: Round hair follicles make straight hair, flattened or c-shaped hair follicles make curly hair, and oval hair follicles make wavy hair. Hair texture is a continuous trait, meaning that hair can be straight or curly or anywhere in between. Multiple genes control hair texture, and different variations in these genes are found in different populations. For instance, curly hair is common in African populations, rare in Asian populations, and in-between in Europeans.
Hairline Shape: If your hairline forms a point at the center of the forehead, you have a widow's peak. If not, you have a straight hairline.
Hand Clasping: Without thinking about it, fold your hands together by interlocking your fingers. Which thumb is on top—your left or your right? One study found that 55% of people place their left thumb on top, 45% place their right thumb on top, and 1% have no preference.
Red/Green Colorblindness: Red-green colorblindness is caused by a single gene located on the X-chromosome. This gene codes for a protein in the eye that detects certain colors of light and can cause the eye to not differentiate between red and green.
After students complete the survey, have them tally their group information on the data table (page 2) and draw a bar graph (page 3) of the worksheet.
Script: What similarities and differences are you noticing between you and your teammates? Now you may be tempted to think more common traits are “better” but that is not the case. Sometimes some traits show up more frequently than others in the human population.
Script: Let’s learn more about the way that characteristics can be passed down from one generation to the next generation. Let’s watch a video: Generation Genius: Intro to Traits (www.generationgenius.com) (show video until minute 7:00)
In this hands-on activity students track and record the passage of colored "pompom traits" through three generations of ginger-bread people. In doing so, students learn that traits are passed from parents to offspring and that siblings may or may not receive the same traits from their parents.
Script: Complete the discussion worksheet with your group members. Will the four kids look identical to (have the same traits as) their parents? Did all four children inherit exactly the same traits or is there some variation? . How many of the four children inherited a trait from each one of the grandparents? Is there a child that didn’t inherit a particular trait? If so, which trait (color) was it?
There are few key points I want you to know about traits:
In this activity, students create and decode a "DNA recipe" for a pet dog to observe how variations in DNA lead to the inheritance of different traits. Strips of paper (representing DNA) are randomly selected and used to assemble a DNA molecule. Students read the
DNA recipe to create a drawing of their pet, and compare it with others in the class to note similarities and differences.
*Activity adapted from: https://teach.genetics.utah.edu/
Script: Every organism inherits a unique combination of traits. DNA is a set of instructions that specifies the traits of an organism. Information in the DNA molecule is divided into segments (called genes). Differences in the DNA “alphabet” are what make differences in traits (just like a different sequence of letters makes different words, and a different recipe).
Note to Teacher: Are any two dogs alike? Point out that every dog shares some traits in common with others, but each has an overall combination of traits that is unique. Variations in each DNA strand (the sequence of symbols) led to the inheritance of different traits.
Script: Lastly, let us talk about how some traits are acquired and not inherited. Some of the traits animals and plants have, they got from their parents. They were inherited. But other traits come from the environment. For example, flamingos are pink because of what they eat. When flamingos are born, they are gray. But they eat a lot of shrimp that has beta carotene and that beta carotene gives them their pink color. Another example are hydrangeas. Hydrangeas are flowers that can have different colors depending on the level of acidity in the soil. If the soil is acidic, the hydrangeas will be blue. If the soil is more alkaline or neutral, the hydrangeas will be pink.
Let’s learn more about inherited and acquired traits:
VIDEO: Inherited & Acquired Traits (www.youtube.com/@HaneyScience)
What was one interesting fact that you learned from the video? Share with a person near you.
Have students work with a partner to explain to each other the difference between inherited and acquired traits and give some examples of each.
Complete the inventory of traits with your parents and/or siblings and see if you can determine who you inherited your traits from and which ones you might have in common with siblings.
Sources: The lesson is adapted from Introduction to Heredity and Genetics from Teach Genetics Curriculum from the Genetic Science Learning Center at the University of Utah.
