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Chapter 1 A Close-Up View of You
Heredity
Sharpen Your Reading
Diagram the concepts of heredity using a graphic
organizer. As you read, fill in key points along the
branches. Use the following headings: Who
Am I?—Your Identity and Hereditary Factors.
Boost Your Vocabulary
Draw a diagram that shows how information flows in
the brain from one nerve cell to another.
Know Key Terms
heredity
genetics
chromosomes
traits
Punnett square
intelligence
neurons
dendrites
synapse
neurotransmitters
carrier
family tree
When planning for the future, it can help to
look at the influences that shaped your life in the
past. These factors often continue to influence
you. One main factor that affects personal
development is heredity. Your heredity is the
sum of the qualities that were passed from your
ancestors through your parents to you, 1-4. The
qualities you inherit make you a unique human
being. Your hair color, facial features, and height
are examples.
Besides influencing all your physical qualities,
heredity is a major factor in your personality
development. Your heredity influences the way
you look, feel, and behave. Knowing about the
qualities you inherit will give you some insight
to your own potential development. You will also
pass on to your children part of what you inherit
from your parents. The science that studies
heredity is called genetics.
Genes
Each human being begins life with his
or her own set of genetic material. A person
normally inherits 23 rod-shaped particles called
chromosomes from each biological parent.
Chromosomes carry hereditary information
from each parent. The father and mother each
contribute 23 chromosomes. The child inherits a
total of 46 chromosomes. This genetic “blueprint”
exists in the nucleus of every cell in the body.
Chromosomes contain long, ladder-type
strands of DNA that carry genetic information.
The parts of the ladder that carry information
occur in pairs. These are the genes. There are
about 30,000 genes. Genes determine all inherited
characteristics, or traits.
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1-4
These children have physical characteristics similar
to their parents’ because of heredity.