About This Chapter
Praxis Biology: Genetics and Inheritance - Chapter Summary
Individuals have been working to control genes for thousands of years, but the research that formed the basis of modern genetics began around the mid 1800's. In this chapter, you can learn all about Mendel's first and second laws and see applications for each of these theories. This chapter will also cover genetic interactions and introduce you to key terms like recombinant chromosomes, crossing over, codominance and independent dominance. By using all the lessons in this chapter, you'll cover the following list of topics:
- Basics of genetics
- Differing versions of alleles
- Mendel's Law of Segregation and Law of Independent Assortment
- Exceptions to Mendel's laws
- Use of model organisms for human genetics research
- Pleiotropy, epistasis and organelle inheritance
Well-informed instructors present these lessons, making them clear and enjoyable to use. You can watch the videos and/or read the transcripts, and then complete the quizzes for each lesson. If you want to go back to a certain topic in a video, convenient video tags can take you to exactly the right portion. Many of the lessons also contain links to extra text-only lessons that provide even more support on related topics.
Praxis Biology: Genetics and Inheritance Objectives
Praxis questions that pertain to evolution and classical genetics comprise about 15% of your test. You should plan to demonstrate an understanding of Mendel's laws, exceptions to Mendel's laws, genetic problems linked to chromosomal changes, causes of genetic differences and the links between genetics and evolution. You'll answer about 23 multiple-choice questions on these topics, for which the experience gained with these quizzes can be valuable.
1. Genetics: Heredity, Traits & Chromosomes
We view manipulation of genes in our crops and livestock as a recent development. Yet, man has been manipulating the genetic makeup of his food for thousands of years through cultivation and breeding. This lesson will begin to help you understand how genetics works.
2. Properties of Alleles
What is a dominant phenotype and how will it affect Adrian's flying hamster research? Tune in as he studies homozygous and heterozygous genotypes and the phenotypes they produce.
3. Mendel's First Law: The Law of Segregation
Breaking up is a hard thing to do, but homologous chromosomes always go their separate way. What effect does chromosome segregation have on genetics? We look once more to Adrian's flying hamsters for answers.
4. Application of Mendel's First Law
Hollywood Squares? No, it's Punnett Squares! Those wacky diagrams are a geneticist's best friend. See how they turn geneticists into soothsayers, predicting the genotypic and phenotypic future.
5. Mendel's Second Law: The Law of Independent Assortment
Understanding how Mendel's law of independent assortment describes inheritance of genes is as easy as flipping a coin. Grab a few coins, cue up the video and see how.
6. Mendel's Dihybrid Cross Example: Practice & Ratio
Oh no! Twice the genes and sixteen genotypes - a dihybrid cross seems overwhelming to understand. Never fear though, Punnett squares will save the day!
7. 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.
8. 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?
9. Crossing Over & Gene Linkage: Definition, Importance & Results
During this latest development of his flying hamster experiments, Adrian must learn about linked genes and recombinant chromosomes to unlock the mystery of the fire-breathing hamster. In this lesson, you'll look at another exception to Mendel's law of independent assortment.
10. Human Genetics: Multifactorial Traits & Model Organisms
How do we study human genetics when most traits arise from multiple genes? It's certainly more complicated that drawing a simple Punnett square. Never fear, for model organisms are here!
11. 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.
12. Epistasis: Definition & Examples
Labradors come in three different colors due to two different genes. In this lesson, find out how epistasis works as one phenotype is controlled by the products from two or more genes.
13. Pleiotropy: Definition & Examples
There are many different mutations that occur during growth in organisms. Many times, these mutations can be passed on and will occur in such a way as to be beneficial to the organism. Sometimes, they are not. We will be looking at one such type of mutation here.
14. Organelle Gene Inheritance
Genetic material can be found outside of a cell's nucleus within other organelles of the cell. In this lesson, you will learn about how this DNA is uniquely passed on from parent to offspring.
15. Punnett Square: Definition & Example
This lesson will define what a Punnett square is and show several examples of how one can be used. It will also briefly describe patterns of inheritance.
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