Unit A Lesson 14: Other Types of Inheritance
Completion requirements
Unit A Lesson 14: Other Types of Inheritance |
Learning Targets |
Inquiry Question: Can a leopard (or chicken!) change its spots?
Sometimes traits are not "all or nothing". There might be part of a trait observed, or two traits might combine to make something completely different.
Sometimes traits are not "all or nothing". There might be part of a trait observed, or two traits might combine to make something completely different.
At the end of this inquiry, you should be able to answer the following questions:
- What is incomplete dominance?
- What is co-dominance?
- What traits are heritable?
- What traits are non-heritable?
Pages 28, 53 and 54 in your textbook will help you answer these questions about other types of inheritance.
Introduction
For some traits, one allele does not have complete dominance over another allele.
As a result, when the gene-pair is heterozygous (hybrid) you will either see a blending of the traits (incomplete dominance) or both traits are fully expressed (co-dominance). The pink rose would be an example of incomplete dominance when a red and a white rose are bred.
The red and white colours blend to make a pink colour. The red and white flower would be an example of co-dominance. The red and white colours are both expressed. Incomplete dominance and co-dominance is the backbone to the unique colours that you see in flowering plants. Gardeners and florists delight in the unusual plant colours that come on the market each spring.
As a result, when the gene-pair is heterozygous (hybrid) you will either see a blending of the traits (incomplete dominance) or both traits are fully expressed (co-dominance). The pink rose would be an example of incomplete dominance when a red and a white rose are bred.
The red and white colours blend to make a pink colour. The red and white flower would be an example of co-dominance. The red and white colours are both expressed. Incomplete dominance and co-dominance is the backbone to the unique colours that you see in flowering plants. Gardeners and florists delight in the unusual plant colours that come on the market each spring.
Human Connection
Curly hair is dominant over straight hair. However, individuals that are hybrids will have hair that is wavy. This would be an example of incomplete dominance, because there is a blending of the two traits.
Curly hair is dominant over straight hair. However, individuals that are hybrids will have hair that is wavy. This would be an example of incomplete dominance, because there is a blending of the two traits.
Watch
Watch "Co-dominance - Incomplete Dominance" to review what you have learned.
Blood type is an example of co-dominance in humans. It is a more complex example because it also involves three alleles (A, B and O) where A and B are co-dominant, but O is recessive. An individual with an AB blood type is an example of co-dominance, both traits are fully expressed.
Heritable and Non-Heritable Traits
The concept of which traits are inherited and which traits are not was introduced in lesson 8. You are now revisiting this topic since you have gained an understanding of patterns of inheritance.
The concept of which traits are inherited and which traits are not was introduced in lesson 8. You are now revisiting this topic since you have gained an understanding of patterns of inheritance.
Some heritable traits, such as blue eyes, cannot be influenced by the environment. If a child inherits blue eyes from their parents, they will have blue eyes.
Not all traits or characteristics are inherited, some are acquired, such as a scar. Can you think of other characteristics or traits that can be acquired instead of inherited? Acquired traits are referred to as non-heritable. These
traits will not be passed on to offspring.
Many traits contain both a heritable component and can be influenced by the environment. How many cavities do you have? How many fillings do your parents have? Does brushing and diet affect the health of teeth?
Connections
Connections: Health
>> Thalidomide
In the 1950s, pregnant mothers with morning sickness were given a medication called thalidomide. These mothers gave birth to babies born with missing or deformed limbs. These babies grew up to have typical children, which meant their DNA was normal and that the missing limbs were due to the environment while they were in their mother’s womb. Deformed limbs was a non-heritable trait caused by the mothers taking thalidomide.
Many countries around the world, including Canada, approved the drug for use. Hundreds of affected of Canadians were awarded payments from the Canadian government in 2015 for their suffering.
>> Thalidomide
In the 1950s, pregnant mothers with morning sickness were given a medication called thalidomide. These mothers gave birth to babies born with missing or deformed limbs. These babies grew up to have typical children, which meant their DNA was normal and that the missing limbs were due to the environment while they were in their mother’s womb. Deformed limbs was a non-heritable trait caused by the mothers taking thalidomide.
Many countries around the world, including Canada, approved the drug for use. Hundreds of affected of Canadians were awarded payments from the Canadian government in 2015 for their suffering.
Watch
The video "Spain Thalidomide Victims Seek Compensation" covers this historic issue.