About This Chapter
How It Works:
- Identify the lessons in the Holt McDougal Biology Extending Mendelian Genetics chapter with which you need help.
- Find the corresponding video lessons with this companion course chapter.
- Watch fun videos that cover the extending Mendelian genetics topics you need to learn or review.
- Complete the quizzes to test your understanding.
- If you need additional help, rewatch the videos until you've mastered the material or submit a question for one of our instructors.
You'll learn all of the biology topics covered in the textbook chapter, including:
- Recessive, dominant and lethal alleles
- Sex linked and sex limited traits
- Codominance and incomplete dominance
- Definition of polygenetic traits
- Gene linking and mapping
- Pedigree analysis
- Karyotype disorders
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1. Lethal Alleles: Definition & Examples
Some alleles are recessive, some are dominant, and some are just plain bad. In this lesson, we'll learn about how rare lethal alleles can affect the survival of an organism. Specifically, we'll talk about how something like coat color can be lethal in agouti mice.
2. Exceptions to Independent Assortment: Sex-Linked and Sex-Limited Traits
More men are color blind compared women. But often, not every brother, cousin or uncle in a family tree is color blind. Why not? How can genetics explain this seemingly complex inheritance pattern?
3. Exceptions to Simple Dominance: Codominance and Incomplete Dominance
Have you ever wondered what it means if someone is a universal donor or acceptor of blood? See how genetic interactions play a key role in this trait.
4. Polygenic Traits: Definition & Examples
If variety is the spice of life, polygenic inheritance is one genetic mechanism giving us a continuous range of possibilities. In this lesson, learn how a polygenic trait, like height, can be controlled by multiple genes.
5. Genotype-Environment Interaction and Phenotypic Plasticity
It's not just what's in your genes. In this lesson, we'll begin to explore how some phenotypes are influenced by the interaction between a genotype and the environment. Further, some organisms rely on phenotypic plasticity to change in response to the environmental changes.
6. Gene Linking & Mapping: Definition & Example
This lesson explains gene linking. Gene linkage was first understood by Thomas Hunt Morgan. His experiments are used as examples to show how gene linkage can be used to understand gene mapping.
7. Pedigree Analysis in Human Genetics: Inheritance Patterns
So you've learned what a pedigree is and how to read or even create one. Now you're ready to learn how to analyze a pedigree and figure out what kind of inheritance pattern a genetic condition follows!
8. Pedigree Analysis in Human Genetics: Tutorial
One of the oldest genetic techniques is pedigree analysis, and yet it is still used every day all around the world by doctors, geneticists, and genetic counselors. Building and reading a pedigree is actually fairly easy if you know what the symbols mean. In fact, it's so easy that you can learn how to do it in less than ten minutes if you watch this video!
9. Karyotype: Definition, Disorders & Analysis
Some people with chromosomal disorders may have too many or too few chromosomes in their cells. A karyotype analysis can be used to look at the number and appearance of chromosomes in individuals. Keep reading to learn more.
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Other chapters within the Holt McDougal Biology: Online Textbook Help course
- Holt McDougal Biology Chapter 1: Biology in the 21st Century
- Holt McDougal Biology Chapter 2: Chemistry of Life
- Holt McDougal Biology Chapter 3: Cell Structure & Function
- Holt McDougal Biology Chapter 4: Cells & Energy
- Holt McDougal Biology Chapter 5: Cell Growth & Division
- Holt McDougal Biology Chapter 6: Meiosis & Mendel
- Holt McDougal Biology Chapter 8: From DNA to Proteins
- Holt McDougal Biology Chapter 9: Frontiers of Biotechnology
- Holt McDougal Biology Chapter 10: Principles of Evolution
- Holt McDougal Biology Chapter 11: The Evolution of Populations
- Holt McDougal Biology Chapter 12: The History of Life
- Holt McDougal Biology Chapter 13: Principles of Ecology
- Holt McDougal Biology Chapter 14: Interactions in Ecosystems
- Holt McDougal Biology Chapter 15: The Biosphere
- Holt McDougal Biology Chapter 16: Human Impact on Ecosystems
- Holt McDougal Biology Chapter 17: The Tree of Life
- Holt McDougal Biology Chapter 18: Viruses & Prokaryotes
- Holt McDougal Biology Chapter 19: Protists & Fungi
- Holt McDougal Biology Chapter 20: Plant Diversity
- Holt McDougal Biology Chapter 21: Plant Structure & Function
- Holt McDougal Biology Chapter 22: Plant Growth, Reproduction & Response
- Holt McDougal Biology Chapter 23: Invertebrate Diversity
- Holt McDougal Biology Chapter 24: A Closer Look at Arthropods
- Holt McDougal Biology Chapter 25: Vertebrate Diversity
- Holt McDougal Biology Chapter 26: A Closer Look at Amniotes
- Holt McDougal Biology Chapter 27: Animal Behavior
- Holt McDougal Biology Chapter 28: Human Systems & Homeostasis
- Holt McDougal Biology Chapter 29: Nervous & Endocrine Systems
- Holt McDougal Biology Chapter 30: Respiratory & Circulatory Systems
- Holt McDougal Biology Chapter 31: Immune System & Disease
- Holt McDougal Biology Chapter 32: Digestive & Excretory Systems
- Holt McDougal Biology Chapter 33: Protection, Support & Movement
- Holt McDougal Biology Chapter 34: Reproduction & Development