Concepts of Genetics

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Lecture Notes with Key Figures PowerPoint® Presentation for


Concepts of Genetics

Eighth Edition

Klug, Cummings, Spencer

Chapter 1

Introduction to Genetics

Copyright © 2006 Pearson Prentice Hall, Inc.

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 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.

C
HAPTER

C
ONCEPT
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.

C
HAPTER

C
ONCEPT
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.

C
HAPTER

C
ONCEPT
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.

C
HAPTER

C
ONCEPT
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.

C
HAPTER

C
ONCEPT
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.

C
HAPTER

C
ONCEPT
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.