1/17/2024 - Genetics

• STEM
• 7-9 Grade
• 9-12 Grade

 Genetics

What does the term Genetics mean to you?

Who is the founder of Genetics?

1. Charles Darwin
2. Marie Curie
3. Louis Pasteur
4. Gregor Mendel

What plant did Mendel use for his genetic experiment?

1. Tomato plant
2. Sunflower plant
3. Rose plant
4. Pea plant

In genetics, what is a dominant trait?

1. A trait that is always inherited
2. A trait that only affects males
3. A trait influenced by the environment
4. A trait that masks recessive traits

What is the characteristic of a dominant trait?

1. It is only passed down from the father
2. It is represented by a capital letter
3. It is always visible in the phenotype
4. It is present in homozygous recessive individuals

How is a recessive trait expressed?

1. When an individual carries only one recessive allele for the trait
2. When an individual carries both dominant and recessive alleles for the trait
3. When an individual carries two recessive alleles for the trait.
4. When an individual carries two dominant alleles for the trait

What is phenotype?

1. The genetic code of an organism.
2. The behavior of an organism.
3. The habitat of an organism.
4. The physical or observable traits of an organism.

What is an example of a phenotype?

1. The speed of a moving car.
2. The orbit of a planet.
3. The acidity of a solution.
4. Eye color in humans.

Doggy Genetics

A dog's coat color is determined by which genes are inherited from the dog's parents and grandparents.  The black coat color is a dominant gene, meaning that it is stronger than the opposite gene within two strands of DNA.  The yellow coat color is a recessive gene, meaning that it is weaker than the opposite gene within two strands of DNA. 

Doggy Genetics

To represent the dominant black coat gene, we will use a capital B.

To represent the recessive yellow coat gene, we will use a lowercase b. 

When a dog has both the B and the b gene we will write it as Bb, but because B is dominant the dog's coat will be black.  A dog can only have a yellow coat if it's having the genes bb. 

On the next slide we are going to figure out the different generations of dogs in one family.  Both parents will have the gene expression Bb.

B

b

B

b

Complete the Punnett Square below.  Both parents have black coats and the gene Bb. 

B B

Bb

bb

bb

What colors of coats do the offspring have from your Punnett square? How many colors of each coat?

1st Generation grandparent

1st Generation grandparent

1st Generation grandparent

1st Generation grandparent

2nd Generation parent - gene expression is BB

2nd Generation parent - gene expression is bb

3rd Generation child Drag the options from the right to the boxes below

3rd Generation child

options

Dog Family Tree

What do you notice about the dog family tree on the previous slide?

What have you learned about Genetics and Gene Expression?

Can genetic or environmental factors affect the chances of getting a certain disease?

Materials

Four different desks

8 Bowls 

Skittles (24 of each color:  red, green, yellow, purple)

six-sided dice

Background Information

Our immune systems are made up of different cells and organs that normally defend us against pathogens (harmful microorganisms that can make us sick). The immune system goes through a process called the immune response to fight off a pathogen. Most of the work is done by white blood cells. There are several different types of white blood cells, including B cells and T cells; collectively, the different types of white blood cells are also called leukocytes. White blood cells must find the pathogen in the body, tell it apart from the body's regular cells, then make antibodies, which are tiny particles specifically designed to only attach, or bind, to the pathogen. Once bound to the pathogen, antibodies get help from white blood cells to destroy the pathogen.

Background Information

The process by which the immune system tells pathogens apart from own body cells is called self/nonself-recognition (Figure 1). If it fails, it can cause autoimmune disease or an infection. When the immune cells accidentally make an antibody that binds to its own body cells, it is called autoimmunity, or an autoimmune response, while the antibody is called an autoantibody. Autoimmunity is common and usually not serious, but if it is not stopped by the body, it can turn into an autoimmune disease, which is when the immune system chronically attacks healthy cells in the body. A person's genetics can make them predisposed, or more likely, to get an autoimmune disease. For example, some mutations within specific genes can cause an autoimmune disease. Environmental factors, such as where a person lives, what a person eats, and things that a person is exposed to, can also affect whether a person gets an autoimmune disease.

There are three checkpoints that the immune system follows in order to stop an autoimmune response from becoming an autoimmune disease (note that these steps are simplified).

Background Information

Checkpoint 1: Sometimes, white blood cells (specifically B cells, which are made in the bone marrow, or T cells, which are made in the thymus) are made that have autoimmunity, meaning their antibodies bind to healthy body cells. The body must destroy them before they escape from the bone marrow or thymus, or they can cause an autoimmune disease.

Checkpoint 2: Right before an immune response is triggered to fight a pathogen, white blood cells (called regulatory T cells) make sure that other white blood cells are not accidentally attacking the body's own cells. They need to do their job correctly to prevent an autoimmune disease.

Checkpoint 3: After a pathogen is destroyed in the body, white blood cells (specifically activated T cells and B cells) must destroy themselves (through a process called apoptosis) to stop the immune response, or it could lead to an autoimmune disease.

Background Information

One common autoimmune disease that you could discuss with your students is diabetes mellitus type 1, more commonly known as type 1 diabetes. Type 1 diabetes is caused when the immune system attacks and destroys beta cells in the pancreas that normally make insulin. Before the effects of type 1 diabetes become visible, autoantibodies can be detected. Even if a person has autoantibodies, they are not guaranteed to get type 1 diabetes, but they do have an increased likelihood of developing diabetes over their lifetime. The more types of autoantibodies that are present, the greater the risk.

The incidence varies from about 0.013% of people in Northern Europe and the United States, to a high of 0.035% of people in Scandinavia and a low of 0.001% of people in Japan and China. There is a genetic component to this condition, but it is not completely genetic—environmental factors also matter. If it were completely genetic, then if one identical twin had diabetes, the other twin would also get it; however, medical records show that if one identical twin has diabetes, the other twin is only 30–50% likely to also get it. This, among other medical evidence, shows that both genetics and environment matter.

In this activity, students will use M&M's candies and a die to model the immune system and find out how a person's predisposition (genetics and other factors) affect whether they get an autoimmune disease or not.

Instructions for the Experiment

Step one:  Everyone will select one skittle (color) to be designated as "self".

Step two:  Students will move through the 1st checkpoint and select a skittle (without looking).  If the color matches your 1st skittle you will role a die.  Numbers 1-5 means you move to Checkpoint number 2.  Rolling a 6 means you have acquired an autoimmune disease. 

If the color is a different color than your 1st skittle you will move to checkpoint number 2. 

Instructions for the Experiment

Students who have acquired an autoimmune disease will not move to the next checkpoint.  They will move to the side of the room designated for autoimmune disease. 

Students that did not acquire an autoimmune disease will move through the next checkpoint and repeat the step 2 with the next checkpoint.  

Step 2 will be repeated until a student acquires an autoimmune disease or has completed all the check points. 

At checkpoint 2, if the you select your own color, then you roll the die as you did at checkpoint one.  If you roll a 6 you have acquired and autoimmune disease.  You will roll a second die, 2-6 means you are predisposed to an autoimmune disease.  If you orginally rolled a 1-5, you will roll a second die.  If you roll a 1 you are predisposed to an autoimmune disease, however, you will move through the next checkpoint. This step will be repeated through the next checkpoint. 

How many students acquired an autoimmune disease? How many did not?

Did all predisposed people with a higher risk of getting an autoimmune disease actually get one, or were there any who did not?

What is the immune system's response in autoimmune disease?

1. Produces extra antibodies
2. Kills foreign invaders only
3. Halts all immune activity
4. Attacks the body's own cells and tissues

What is a potential cause of autoimmune diseases?

1. Genetic predisposition and environmental factors
2. Excessive vitamin intake
3. Lack of sleep
4. Poor diet and exercise habits

Which of the following factors may contribute to the development of autoimmune diseases?

1. Physical activity
2. Environmental triggers
3. Genetic predisposition
4. Dietary habits

How can environmental factors potentially impact the risk of acquiring an autoimmune disease?

1. By enhancing the body's defense mechanisms
2. By triggering the immune system to attack healthy cells
3. By reducing inflammation