Download Genotypes and Phenotypes Genetic Foundations Boy or Girl

Genotypes and Phenotypes
Genotype
Phenotype
Genetic make-up of
an individual
Observable
characteristics of
an individual
Copyright © Allyn & Bacon 2004
Genetic Foundations
• Chromosomes – store
and transmit genetic
information.
• Genes – segments of
DNA located along the
chromosomes
• DNA – substance of
which genes and
chromosomes are made.
Copyright © Allyn & Bacon 2004
Genetic Counseling
Boy or Girl?
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The 22 pairs of matching chromosomes
within a human cell are called the
autosomes.
The twenty-third pair consists of sex
chromosomes. Females have an XX pair
of sex chromosomes; males have an XY
pair.
The sex of the new organism is determined
by whether an X-bearing or a Y-bearing
sperm fertilizes the ovum.
Due to advances in genetic counseling and
prenatal diagnosis, people can make informed
decisions regarding conceiving, carrying a
pregnancy to term, or adopting a child.
Genetic counseling is a communication process
designed to help a couple to assess the likelihood
of giving birth to a baby with a hereditary disorder
and to choose the best course of action in view of
risks and family goals. (pp. 65-66)
The genetic counselor interviews the couple and
prepares a pedigree, a picture of the family tree in
which affected relatives are identified. The pedigree
is used to estimate the likelihood that parents will
have an abnormal child.
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Environmental Contexts
for Development
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Family
Socioeconomic Status
Neighborhoods
Towns and Cities
Cultural Context
Environmental Influences on
Gene Expression
• The relationship between heredity and environment is
not a one-way street, from genes to environment to
behavior.
• Rather, it is bidirectional; genes affect children’s
behavior and experiences, but their experiences and
behavior also affect gene expression.
• Stimulation of both internal and external environments
(to the child) triggers gene activity.
• Epigenesis means the development of the individual
resulting from ongoing, bidirectional exchanges between
heredity and all levels of environment.
• The success of any attempt to improve development
depends on the characteristics we want to change, the
genetic makeup of the child, and the type and timing of
our intervention.
Copyright © Allyn & Bacon 2004
The Epigenetic Framework
Copyright © Allyn & Bacon 2004
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