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LECTURE
CONNECTIONS
1 | Introduction to Genetics
© 2009 W. H. Freeman and Company
Hopi Native Americans
•
Albinism, a genetic condition, arises with high frequency among
the Hopi people and occupies a special place in the Hopi culture
(1 in 200 people).
•
Albinism is caused by defects in any of the 4 genes that control
the synthesis and storage of melanin.
•
Why is albinism so frequent among the Hopi Native Americans?
Introduction to Genetics
• The importance of genetics:
- Albinism in the Hopi Native
Americans: genetics altered the
occupation, the role in Hopi
society, and relations with other
members of the tribe.
- Genes affect our height, weight,
hair color, skin pigmentation, etc.
- Genes can influence our
susceptibility to many diseases
and disorders.
- Genes contribute to our
intelligence and personality;
- Agriculture;
- Domestication of plants and
animals;
- Pharmaceutical industry: drugs
and food additives are synthesized
by fungi and bacteria that have
been genetically manipulated to
make them efficient producers of
these substances.
Examples: growth hormone,
insulin and clotting factor.
- Genetics play a critical role in medicine (sickle-cell anemia);
- Gene therapy;
- Evolution: is the genetic change taking place through time;
- Taxonomy, ecology, and animal behavior are making
increasing use of genetic methods;
- Developmental Biology: tissues and organs form through
the regulated expression of genes.
Genome
• Genome is a complete set of genetics instructions for
any organism.
• All genomes are encoded in nuclei acids- either DNA or
RNA.
• Genetic variation is the foundation of all evolutionary
change and is ultimately the basis of all life as we know
it.
• Genetics: past, present and future.
Division of Genetics
• Transmission genetics:
relation between
chromosomes and heredity.
• Molecular genetics:
chemical nature of the gene
itself.
• Population genetics: genetic
composition of individual
members of the same
species.
Model Genetic Organisms
• Model organisms are organisms with characteristics
that make them useful for genetics analysis:
• Common characteristics of model organisms:
- Short generation time;
- Large but manageable number of progeny;
- Adaptable to laboratory environment (can be housed
and propagated inexpensively).
The history of Genetics Organisms
• First evidence that people
understand hereditary:
10,000-12,000 years ago in
the domestication of plants
and animals;
• Greeks (520 B.C.): concept
of pangenesis and
inheritance of acquired
charasteristics.
• Aristotle (384-322 B.C.) believed that both males and
females made contributions to the offspring.
• In 1665, Robert Hooke discovered cells and gave scientists
the idea of preformationism (all traits would be inherited from
only one parent).
• Blending inheritance: offsprings are a blend.
• In 1676, Nehemiah Grew reported that plants reproduce
sexually by using pollen from the male sex cells.
• Gregor Mendel discovered the basic principles of hereditary
in 1866.
• In 1859, Charles Darwin put forth the theory of evolution
through natural selection and recognized that heredity was
fundamental for evolution.
Fundamental terms and principles of genetics
• 2 basic types of cells:
- Prokaryotic: lack a nuclear membrane and possess no
membrane-bounded cell organelles
- Eukaryotic: more complex, possessing a nucleus and
membrane-bounded organelles such as chloroplasts and
mitochondria
• The gene is the fundamental unit of heredity
• Genes come in multiple forms called alleles
• Genes confer phenotypes and genetic information is the
genotype
• Genetic information is carried in DNA and RNA
Nuclei acids are polymers consisting of repeating units called nucleotides;
each nucleotide consists of sugar, a phosphate, and a nitrogenous base
(DNA: A, C, G and T; RNA: A, C, G and U).
• Genes are located in chromosomes
• Chromosomes separate through the processes of mitosis and
meiosis
• Genetic information is transferred from DNA to RNA to protein
• Mutations are permanent
• Some traits are affected by multiple factors
• Evolution is genetic change