Preface

The purpose of this audio-course is to help you learn about the field of genetics at the college-level of understanding. Genetics is the study of how traits are passed on from parent to offspring as well as how things like natural selection affect the genetics of a given population or species. The field of genetics has come a long way since the first research was done on how genetic traits are passed on from generation to generation.

We will also talk a great deal about what is known about genetics at the molecular level. After more than a century of research in this field, scientists who study genetics now know about what genetic material looks like and the molecular processes behind things like cell replication, sexual and asexual reproduction, and genetic mutations in all types of organisms. The knowledge of these things have greatly impacted our understanding of genetic diseases and has paved the way toward being able to manipulate the genetics of a species in everything from cloning to genetic engineering and the use of genetics to treat all types of diseases.

At the completion of this course, you should feel more confident about the large-scale and molecular aspects of genetics as they apply to prokaryotic species and to eukaryotic organisms, such as plants and animals, including humans and our many genetic disease states.

In chapter one in the course, we will talk about some of the basic issues in genetics and genetic research. The history of genetics and how it has been understood in the past is covered in this chapter as well as what we know about genes and chromosomes in prokaryotic organisms and in eukaryotes. Genetics is a broad field of study, with several branches we will touch upon. We will expand on this to talk about molecular gene expression, the genetic code, and how genes become traits, which will be further explained in later chapters.

Chapter two covers the seminal work of Gregor Mendel, partly because no discussion of genetics should not include his work. Mendel worked with pea plants in a systematic way to identify how traits get passed from parent plants to offspring. His work was

important to the modern study of genetics. The chapter also looks into the work of those who discovered the structure of DNA, which opened the door to genetic study even further by identifying what DNA looked like and why this was important to how it works.

The focus of chapter three in the course is molecular genetics, which is one of the major sub-categories of genetics. This deals mainly with DNA, RNA, and how these interact in order to make proteins. What happens to proteins after they are made is called posttranslational modification of proteins, which is how a protein structure gets finalized. How these processes happen is different in prokaryotes and eukaryotes, which will be covered in this chapter.

Chapter four is about gene regulation in prokaryotes and eukaryotes. More accurately, though, the chapter talks about trait regulation because it also focuses on how the entire process from gene regulation to epigenetics occurs. Much is known about how genes in prokaryotes are regulated directly; less is known about gene regulation happens in eukaryotes. As it turns out, there are other regulatory processes, such as translation regulation and epigenetic modification, which involve modifying traits in ways other than through genetic means.

The main focus of chapter five in the course is how cells divide and how organisms reproduce to create the next generation. With bacteria and other prokaryotes, the process is simpler and involves asexual reproduction, which mainly means they undergo binary fission. Mitosis is a method of cell division that is distinct from binary fission and occurs in eukaryotes. Sexual reproduction occurs in plants and animals. It involves a process called meiosis, which is discussed in this chapter. Finally, the chapter ends with the complex topic of sex determination and how this happens from a genetic perspective.

Chapter six is concerned with the different patterns of inheritance seen in genetics. There are dominant and recessive inheritance patterns as well as x-linked inheritance and codominant inheritance. The topics of pleiotropy, lethal alleles, and epistasis or gene to gene interactions are covered in this chapter as well. Many disorders have multigenic or polygenic inheritance patterns, which involve many different genes. Some

of the major genetic diseases in humans and their inheritance patterns are discussed at the end of this chapter.

Chapter seven in the course covers extranuclear genetics in eukaryotes, which mainly involves the genetics involved in the mitochondria and chloroplasts of these cells. The first topic of discussion is the theory of endosymbiosis, which is how it is believed that these structures first entered other cells to create organelles inside eukaryotes instead of being separate entities. The different genetic issues of chloroplast and mitochondrial DNA are covered in this chapter, including the epigenetics we know about so far that influence mitochondrial gene expression.

The focus of chapter eight is the different variations possible in chromosome structure and number, which is largely a phenomenon of eukaryotes. There are many different chromosome variations to consider in both plants and animals. In this chapter, we discuss polyploidy, which is having more than one set of chromosomes, aneuploidy, which involves any variation in chromosome number beyond what is normal for the species, and things like insertions, deletions, inversions, and translocations—all of which affect part of a chromosome and affect how the chromosome behaves in the cell or organism.

Chapter nine in the course is about the different mechanisms of gene transfer, also called lateral gene transfer or horizontal gene transfer. There are different ways that genes can be transferred from the environment or between bacteria, which is a form of sexual reproduction among prokaryotes, even though it is not sexual in the traditional way. Lateral gene transfer has implications in medicine, largely because it is through these mechanisms that things like antibiotic resistance occurs. These issues are discussed as part of this chapter.

Chapter ten provides a discussion of viruses from a genetic perspective. You’ll learn the different types of viruses in terms of structure and the different aspects of their genetic makeup. The genetics of viruses, including how and why they mutate over time is covered as well as how they invade a host and ultimately replicate. Viruses have implications in industry, technology, and medicine, which are talked about in this

chapter. Finally, some viruses contain genes that promote cancer in their host. How they do this is part of this chapter.

The focus of chapter eleven in the course is gene mutation and how DNA repairs itself on a regular basis in order to fix mutations that could otherwise damage or kill the cell. In this chapter, we talk about the different types of mutations, the various mutagens and how they cause DNA abnormalities, and how these mutations are ultimately fixed in the vast majority of cases. While DNA mutations lead to a wide variety of human genetic diseases, the ways in which mutagens lead to cancer is discussed as part of this chapter.

Chapter twelve looks at some ways that genes, DNA, and their products are studied and used in certain technologies. This is a new area of research that is continually evolving and looks at ways to clone genes, sequence genes and chromosomes, and separate DNA, RNA, or proteins using blotting techniques. As you’ll see, these technologies have been employed in medicine using things like the polymerase chain reaction. Also covered in this chapter is genomics, including structural and functional genomics and how these are used in DNA technologies.

The focus of chapter thirteen in the course is biotechnology, which is how modern science has taken earlier genetic research and applied it to technology so that all aspects of modern life are potentially infected. Issues like how microorganisms can be used in biotechnology and the creation of genetically modified animals and plants have been areas where this technology has most been applied to everyday life in modern societies. Gene therapy is just now becoming a reality and, while there is much more to do in this area, this will also be discussed in this chapter.

Chapter fourteen involves the common issues seen in understanding population genetics, including how population genetics interacts with principles of evolution to affect the genetic diversity of the world’s living things. In the chapter, we discuss genetic screening in human populations and why it is done. Other important aspects of population genetics we talk about in the chapter include genetic drift, migration, nonrandom mating, natural selection, and the Hardy-Weinberg principle, which are all ways of understanding why we have genetic diversity in the different populations on earth.