Download Chapter 3 Section 4

Ch. 3 S. 4
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Chapter 3 Section 4
Heredity: Our Genetic Background
Obj: Explain the role of _______________________ and _____________ in heredity, and
evaluate the methods used by psychologists to study the ___________ of heredity in
determining traits.
Role of Chromosomes and Genes in Heredity
__________________ is the transmission of characteristics from parents to
____________________. We study this as a means of understanding why people behave
as they do. Heredity plays a key role in the development of _________, and psychological
disorders.
Genes and Chromosomes
_____________ are the basic building blocks of heredity and traits are determined by pairs of
genes, with one gene in each pair inherited from each ______________. Some traits, such
as blood type, are controlled by a single __________ of genes; some are more complicated
and involve combinations of genes.
Genes are found in threadlike structures called ______________________, which are
composed of deoxyribonucleic acid (________). DNA takes the form of a double helix.
Most normal human cells contain 46 chromosomes that are organized into 23 pairs. In each
of the 23 pairs, one chromosome comes from the father and the other chromosome comes
from the mother. Each chromosome contains instructions for the _________________ of
particular traits in the individual.
Researchers have learned that 22 of the ____ pairs of chromosomes are similar in males and
females. The 23rd pair, the sex chromosomes, determines whether we are female or male.
In males, the 23rd pair consists of an ___ chromosome (so called because of its X shape)
and a ___ chromosome (because of its Y shape). Females have two X chromosomes, so
they always pass an X chromosome on to their offspring.
When a child is born without 46 chromosomes in each cell, _____________ and
________________ disorders may result. One of the most common disabilities of this type
occurs when there is an extra, or third, chromosome on the 21st pair. When this happens, a
baby will be born with _______ syndrome. People with Down syndrome usually have some
level of mental retardation and may have heart and respiratory problems.
The Nature-Nurture Debate
People have debated the role that _______________ (biological makeup, what we inherit)
plays in forming who we are, versus _______________ (refers to environmental factors we
are exposed to). Most scientists believe that it is a combination of __________.
The Study of the Role of Heredity
Role of ________________ in studies through various types of kinship research such as:
– Twin Studies – a useful way to learn about nature and nurture.
– ____________ Studies – provide ways of sorting out the effects of nature and nurture.
– Twins Reared Apart – a way of finding out that twins reared apart share many of the
same mannerisms despite their ____________________.