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Powerpoint Lecture Outline
Human Genetics
Concepts and Applications
Eighth Edition
Ricki Lewis
Prepared by
Dubear Kroening
University of
Wisconsin-Fox Valley
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Chapter 1
Overview of Genetics
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Genetics
• Is a life science
• Is the study of inherited variation and
traits
• Genes are the units of heredity
• Genes are composed of
Deoxyribonucleic Acid (DNA)
• Traits are produced by an interaction
between the genes and the
environment
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Genes
• Contain the
instructions
within the cells
for protein
production
Figure 1.1
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The Genome
• Is the complete set of genetic information
for an organism
• It includes:
– All of the genes present in an
organism and
– Other DNA sequences that do not
encode genes
• Human genome was sequenced in 2000
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Levels of Genetics
Figure 1.2
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Deoxyribonucleic Acid (DNA)
A double stranded polymer consisting of a chain of
nucleotides
• Deoxyribonucleotide components:
• Phosphate
• Sugar: Deoxyribose
• Base:
Guanine G
Adenine A
Thymine T
Cytosine C
• The sequence of the bases code for the amino acid
sequence in a protein
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Reading1.1, Figure 1
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Ribonucleic Acid (RNA)
• Single stranded polymer of ribonucleotides
• Ribonucleotides components:
• Phosphate
• Sugar: Ribose
• Base:
Guanine G
Adenine A
Uracil
U
Cytosine C
• Several types
• Uses information on DNA to construct proteins
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Reading 1.1, Figure 2
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Genome
• Proteomics – which genes are expressed in
cell types
• Only 1.5% of the DNA in the human genome
encodes protein
• Rest includes highly repeated sequences with
unknown functions
• Includes about 24,000 protein encoding genes
• Cataloged in database
– Mendelian Inheritance in Man (MIM)
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Genes
• Alleles are variants of genes
• They form by mutation
• Mutations in sperm or egg cells are passed
on to the next generation
• May be positive, negative, or neutral
• Examples
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Variations
• Polymorphisms are variations in the
DNA sequence that occur in at least 1%
of the population
• Single nucleotide polymorphisms
(SNPs) are single base sites that differ
among individuals and are important as
markers
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Chromosomes
•
•
•
•
•
Composed of DNA and protein
Found in the nucleus of the cell
Human cells have 46 chromosomes
22 pairs of autosomes
The sex chromosomes X and Y
– Females have two X chromosomes
– Males have one X and a Y
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A Karyotype
is a chart of the chromosomes organized
by the size of the chromosome pairs.
Figure 1.2
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Cells
• All cells with a nucleus in the body
contain the same genetic information
• Differentiation causes cells to differ in
appearance and function. This is
controlled by variation in gene
expression.
• Stem cells are less specialized and can
become many different cell types
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Levels of Organization
•
•
•
•
•
Cells
Tissues
Organs
Organ systems
Organism
Figure 1.3
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Individual
• The genotype of an individual is the alleles
they carry
• The phenotype is the visible trait
– Dominant alleles are expressed if the
individual carries one or two copies of the
allele
– Recessive alleles are only expressed if the
individual carries two copies of the allele
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The Family
• Inheritance of traits
can be observed in
families.
• A pedigree
indicates the
structure of a family
schematically.
Figure 1.2
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A Population
• Is a group of interbreeding
individuals
• The gene pool is the
alleles in a population
• Evolution is the changing
allelic frequencies in
populations over time.
Figure 1.2
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Evolution
• Comparison of DNA
sequences indicates the
amount of similarity between
two species.
• 98% of human DNA
sequences are shared with
chimpanzees.
• Humans share genes with
mice, fish, fruit flies, yeast,
and bacteria.
Figure 1.4
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Review of Genetic Terms
Table 1.1
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Most Genes Do Not Function Alone
• Mendelian traits are determined by a single
gene
• Most traits are multifactorial and not
controlled by a single gene. They are
influenced by more than one gene and
the environment
• Some illnesses may occur in different forms:
Mendelian, multifactorial, and noninherited
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Genes and Disease Risk
• Mendelian traits have simple inheritance
• Multifactorial traits more complicated
– BRCA1 gene and breast cancer
Ethnic influences as well as environmental
• Knowing risk can help us make good
choices
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Applications of Genetics
• Forensics
Identifying victims, DNA at crime scenes,
overturning convictions, adoptions
• Rewriting history
Thomas Jefferson offspring, the Jewish
Lemba
• Common ancestory
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Figure 1.7
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Applications of Genetics
Health care
• Prediction of disease
– Genetic testing, concerns over privacy
• Development of treatments
• Family planning
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Applications of Genetics
Agriculture
• Biotechnology
• Crop and animal breeding
• Genetically modified foods
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Applications of Genetics
• Ecology
– Metagenomics – sequencing DNA from a
habitat
Sargasso Sea, air samples, human body
• Global perspective and human health
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