Selective Breeding

Genetics & Heredity

Selective Breeding

• Open up your classwork notebooks– Title: Selective Breeding– Date: 04/20/23

Objectives for today

• 1. Define selective breeeding

• 2. Differentiate between the types of selective breeding.

• 3. Define inbreeding, cloning, genetic engineering, and hybridization.

Warm-Up

• When we created our children (either SpongeBob of Sesame Street genetics), were you able to select which male gamete fertilized the female gamete?

• Why or why not?

• Is it possible for parents to select which male gamete will fertilize which female gamete/

Warm-Up Activity

• Take the next few minutes to think about what selective breeding means.

• When you think you have a definition for selective breeding write it down in your notebook.

• After your definition write down a few examples of selective breeding.

Definition

• Selective Breeding- the process of selecting organisms with desired traits to be parents of the next generation.

• This definition is rather technical so let’s come up with a definition that is more user-friendly.

Examples of Selective Breeding

• What are some of the examples of selective breeding that you were able to come up with?

• As we go over these examples make sure to write them down in your notebooks.

Examples of Selective Breeding

• Images from: google.com

Types of Selective Breeding

• For example: A farmer might cross a male and female turkey that are both plump and grow quickly.

• Why would a farmer choose to cross these two turkeys?

• What could be the down side of crossing these two birds, if they are genetically similar?

Types of Selective Breeding

• Cloning- creating organisms that have exactly the same genes as the organism from which it was produced.

• What is an example of cloning that’s occurred in the past 20 years?

Dolly the Sheep

• In 1996, a group of scientists were able to clone a sheep.

• The resulting cloned sheep was named Dolly.

• Dolly was remarkable because she was the first mammal to be succesfully cloned.

How they cloned Dolly

Image from www.science.howstuffworks.com

Issues with Dolly

• Dolly was able to produce 5 offspring in her lifetime.• However, in 2001 Dolly developed arthritis. This onset of

arthritis was early for a normal sheep.• In 2003, Dolly was euthanized because of her arthritis

and a progressive lung disease.• Dolly’s breed of sheep typically live up to 11-12 years

old, where Dolly only lived to be 6 years old.• Scientists are unsure if Dolly developed these symptoms

because she was a clone or due to some other factor.

Issues with Cloning

• What could be some possible issues with cloning, scientifically speaking?

• Think of Dolly’s early onset of arthritis.

• Cloning is common occurrence in plants and bacteria.

• Image from starwars.wikia.com

Types of Selective Breeding

• Genetic Engineering- genes from one organism are transferred into the DNA of another organism.

• This technique is used to help produce medicines and improve food crops.

• Example: scientists have been able to insert genes into tomato and rice plants that enable the plants to survive in cold temperatures or poor soils.

• What could be the benefit for genetic engineering, in the case of the plants?

Genetic Engineering

• Genetic engineering is on the forefront for medical treatments.

• Doctors have used the practice of gene therapy, inserting copies of a gene directly into a person’s cells, to treat diseases.

• For example, doctors could be able to treat hemophilia by replacing the defective allele on the X-chromosome.

Issues with Genetic Engineering

• People are concerned with the long term effects of genetic engineering.

• They fear that genetically engineered crops might not be safe, they may cause harm to the environment or cause health issues in humans.

• How would scientists be able to adress these concerns?

Types of Selective Breeding

• Hybridization- the crossing of two genetically different individuals.

• A hybrid organism is formed to have the best traits from both parents.

• What is an example of hybridization that you have learned about in the past few years?

Extend your knowledge

• We have now covered four different forms of selective breeding.

• In your notebooks write a paragraph on whether or not you agree with selective breeding. Make sure to have at least 2 pros and cons supporting your reasoning.

• Make sure to use your genetics and heredity vocabulary terms.

Back to Hybridization

• The American Chestnut Project

• What is the main goal of the American Chestnut Foundation (ACF)?

• Image from gatacf.org

American Chestnut

• What caused a decline in American Chestnut trees? (There are multiple reasons)

• What two species of Chestnuts are being crossed?

• What are the desirable traits that the ACF are trying gain from both species of Chestnuts?

• What steps are currently being taken to help revive this tree species?

American Chestnut

• You will be given an exit ticket on the American Chestnut project.

• This sheet must be filled out before you can leave the classroom.