Lecture Notes with Key Figures PowerPoint® Presentation for

Concepts of GeneticsEighth Edition

Klug, Cummings, Spencer

Chapter 1Introduction to Genetics

Copyright © 2006 Pearson Prentice Hall, Inc.

Chapter 1Introduction to Genetics

1.1 From Mendel to DNA in Less Than a Century

1.2 Discovery of the Double Helix Launched the Recombinant DNA Era

1.3 Genomics Grew Out of Recombinant DNA Technology

1.4 The Impact of Biotechnology Is Growing

1.5 Model Organisms Play Important Roles in Genetics and Biology

1.6 We Live in the "Age of Genetics"

1.1 From Mendel to DNA in Less Than a Century

• Mendel showed that traits are passed from parents to offspring in a predictable way. His work forms the foundation for genetics.

• In mitosis, chromosomes are copied and distributed so that the two resulting daughter cells each receive a diploid set. In meiosis, the gametes produced are haploid.

• According to the chromosome theory of inheritance, inherited traits are controlled by genes residing on chromosomes. The genes are faithfully transmitted through gametes, maintaining genetic continuity from generation to generation.

• Mutations produce alleles of a gene and are the source of genetic variation.

• DNA, not protein, is the carrier of genetic information.

1.2 Discovery of the Double Helix Launched the Recombinant

DNA Era

• DNA is an antiparallel, double-stranded helix made up of the nucleotides A, C, G, and T. The sugar in its nucleotides is deoxyribose. These nucleotides form A–T and G–C base pairs across the helix (Figure 1‑8).

• Place 01_08.jpg here– Summary of the structure of DNA, illustrating

the nature of the double helix (on the left) and the chemical components making up each strand (on the right).

• RNA is similar to DNA except that it is usually single-stranded and has U in place of T. In addition, the sugar in its nucleotides is ribose instead of deoxyribose.

• DNA is transcribed to RNA, which is translated into protein (Figure 1‑9). This is known as the central dogma of genetics.

• The genetic code consists of triplet nucleotides present in mRNA. Each triplet encodes for insertion of a specific amino acid into a growing protein chain.

• Once a protein is made, its action or location in a cell plays a role in producing a phenotype.

1.3 Genomics Grew Out of Recombinant DNA Technology

• Restriction enzymes have allowed the advent of recombinant DNA and cloning (Figure 1‑14).

• Genomics analyzes genome sequences to study the structure, function, and evolution of genes and genomes.

1.4 The Impact of Biotechnology Is Growing

• Biotechnology has been used for the genetic modification of crop plants for increased herbicide, insect, and viral resistance, as well as for nutritional enhancement. Some genetically altered traits in crop plants are shown in Table 1.1.

• The molecular basis for hundreds of genetic disorders is known (Figure 1‑18). Gene therapy and genetic testing are important parts of medicine.

• Place 01_18.jpg here– Diagram of the human chromosome set,

showing the location of some genes whose mutant forms cause hereditary diseases. Conditions that can be diagnosed using DNA analysis are indicated by a red dot.

1.5 Model Organisms Play Important Roles in Genetics and

Biology

• Model organisms for genetic study are easy to grow, have a short life cycle, and produce many offspring.

• All life has a common origin, and genes with similar functions in different organisms are similar in structure and DNA sequence.

• Recombinant DNA technology and the ability to transfer genes across species has made it possible to develop models of human diseases (Table 1.2).

1.6 We Live in the "Age of Genetics"

• Genetics is the core of biology and the method of choice for understanding the functions and malfunctions of a biological system.

CHAPTER CONCEPT 1

Using pea plants, Mendel revealed the fundamental principles of transmission genetics. Work by others showed that genes are on chromosomes and that mutant strains can be used to map genes on chromosomes.

• Mendel showed that traits are passed from parents to offspring in a predictable way.

• According to the chromosome theory of inheritance, inherited traits are controlled by genes residing on chromosomes that are faithfully transmitted through gametes, maintaining genetic continuity from generation to generation.

CHAPTER CONCEPT 2

The discovery that DNA encodes genetic information and solving the structure of DNA and the mechanism of gene expression form the foundation of molecular genetics.

• DNA is transcribed to RNA, which is translated into protein. This is the central dogma of genetics.

• DNA is an antiparallel double stranded helix made up of the nucleotides A, C, G, and T. These nucleotides form A:T and G:C base pairs across the helix. The complementarity of the two strands provides a mechanism for replication.

CHAPTER CONCEPT 3

The development of recombinant DNA technology revolutionized genetics and is the foundation for genome sequencing, including the Human Genome Project.

• Restriction enzymes have allowed the advent of recombinant DNA technology and gene cloning.

• A draft of the human genome sequence was reported in 2001.

CHAPTER CONCEPT 4

Biotechnology uses recombinant DNA technology to produce goods and services in a wide range of areas, including agriculture, medicine, and industry. The use of biotechnology has raised many legal and ethical issues involving the patenting of genetically modified organisms, and the use of gene therapy.

• The genetic modification of crop plants is one of the most rapidly expanding areas of biotechnology.

• Livestock have been commercially cloned by embryo splitting for more than 25 years. A new method for cloning animals based on nuclear transfer was developed in 1996.

• Genetic testing and gene therapy are important parts of medicine.

CHAPTER CONCEPT 5

Model organisms have been used in genetics since the early part of the twentieth century. The extensive genetic knowledge gained from these organisms coupled with recombinant DNA technology and genomics makes these organisms useful as models to study human diseases.

• Model organisms for genetic study are easy to grow, have a short life cycle, and produce many offspring.

• Recombinant DNA technology and the ability to transfer genes across species has made it possible to develop models of human diseases.

CHAPTER CONCEPT 6

Genetic technology is developing faster than policy, law, and convention in the use of this technology. Education and participation are key elements in the wise use of this technology.

• Although other scientific disciplines are also expanding in knowledge, none has paralleled the growth of information occurring in genetics.