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William S. Klug
Michael R. Cummings
Charlotte A. Spencer
Concepts of Genetics
Eighth Edition
Chapter 1
Introduction to Genetics
Copyright © 2006 Pearson Prentice Hall, Inc.
Why do we have to learn genetics?
生命的傳承
生物醫學上的應用
生物多樣性上的應用
Chapter 1
Introduction 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 (基因體學) Grew Out of Recombinant
DNA Technology (DNA 重組技術)
1.4 The Impact of Biotechnology Is Growing
1.5 Model Organisms (模型生物, 動物模型) 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
• In eukaryotes, DNA resides in the nucleus
and organelles reside in the cytoplasm
(Figure 2-1).
Genetics
Mendel (1866)
Rediscovery (1900)
Carl Correns
de Vries
von Tschermak
Watson and Crick (1953)
Genes and chromosomes are the
fundamental units of genetics
What does “genetics” mean?
Heredity 承傳/遺傳; variation變異
Inherited variation and the underlying
molecular basis
What is the center of heredity in a cell?
What is a gene?
What is a chromosome?
When and how can chromosomes be visualized?
• 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.
How many chromosomes can an organism have?
diploid (2n) 雙倍體
homologous chromosomes 同源染色體
Centromeres 著絲點
Locus/Loci 基因座
Haploid
Polyploid
1.1 From Mendel to DNA
in Less Than a Century
1.1.1 Mendel’s Work on Transmission of Traits
1.1.2 The Chromosome Theory of Inheritance:
Uniting Mendel and Meiosis
1.1.3 Genetic Variation
Figure 1-2
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Figure 1-3
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Figure 1-5
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What is accomplished during the process of mitosis and
meiosis?
•
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.
What are the sources of genetic variation?
Recombination during meiosis
Chromosomal mutations (aberrations):
duplication 複製, deletion 缺失, rearrangement 重組
Gene mutations: smaller changes in DNA
Variation
Alleles 等位基因
Mutations produce alleles of a gene and are
the source of genetic variation.
Genotypes 基因型 vs. phenotype 表現型
Figure 1-6
Copyright © 2006 Pearson Prentice Hall, Inc.
1.1 From Mendel to DNA
in Less Than a Century
1.1.4 The Search for the Chemical Nature of
Genes: DNA or Protein?
• DNA, not protein, is the carrier of genetic
information.
Figure 1-7
Copyright © 2006 Pearson Prentice Hall, Inc.
1.2 Discovery of the Double
Helix Launched the
Recombinant DNA Era
1.2.1 The Structure of DNA and RNA
• 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).
Figure 1-8
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•
•
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.
Figure 1-9
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The genetic code and RNA triplets 三聯體
AUG Met
UUU Phe
UUC
• 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.
1.2.2 Gene Expression 基因表達:
From DNA to Phenotype
Once a protein is made, its action or location in
a cell plays a role in producing a phenotype.
1.2.3 Proteins and Biological Function
Enormous structural diversity
primary structure
secondary structure
tertiary structure
quaternary structure
Figure 1-10
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1.2.4 Linking Genotype to Phenotype:
Sickle-Cell Anemia
Figure 1-11
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Figure 1-12
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Figure 1-13
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1.3 Genomics Grew Out of
Recombinant DNA
Technology
1.3.1 Making Recombinant DNA Molecules
and Cloning DNA
• Restriction enzymes (限制酶) have allowed
the advent of recombinant DNA and cloning
(複製, 克隆) (Figure 1-14).
Figure 1-14
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1.3 Genomics Grew Out of
Recombinant DNA
Technology
1.3.2 Sequencing Genomes:
The Human Genome Project
• Genomics analyzes genome sequences to
study the structure, function, and evolution of
genes and genomes.
1.4 The Impact of Biotechnology
Is Growing
1.4.1 Plants, Animals, and the Food Supply
•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.
Table 1-1
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Figure 1-16
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1.4 The Impact of Biotechnology
Is Growing
1.4.2 Who Owns Transgenic Organisms?
Figure 1-17
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1.4 The Impact of Biotechnology
Is Growing
1.4.3 Biotechnology in Genetics and Medicine
• The molecular basis for hundreds of genetic
disorders is known (Figure 1-18). Gene
therapy and genetic testing are important parts
of medicine.
Figure 1-18
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Figure 1-19
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1.5 Genetic Studies Rely On the
Use of Model Organisms
Model Organisms Play Important
Roles in Genetics and Biology
1.5 Genetic Studies Rely On the
Use of Model Organisms
1.5.1 The Modern Set of Genetic Model
Organisms
Model organisms for genetic study are easy to
grow, have a short life cycle, and produce
many offspring.
1.5 Genetic Studies Rely On the
Use of Model Organisms
1.5.2 Model Organisms and Human Diseases
• 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).
Table 1-2
Copyright © 2006 Pearson Prentice Hall, Inc.
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.