7eCHAPTER TWO - Outline
Reading Highlights:
Overview of chapter topics – page57
chromosomes and DNA- page 52
gametes - page 53
meiosis - pages 53-54
gender / autosomes /sex chromosomes – pages 54-55
multiple births - pages 55-56
patterns of genetic inheritance – pages 56-60
mutation – page 60
polygenic inheritance - page 60
chromosomal abnormalities – pages 60-62
genetic counseling - page 63
pre-natal diagnosis - pages 63-65
adoption – pages 65-68
new reproductive technologies (box) pages 66-67
family influences on development - pages 69-75
SES - page 71
educating girls (box) – page 73
poverty - page 74
cultural context – pages 77-79
public policy - pages 78-81
heredity and environment – pages 82-89
Terms and Concepts:
chromosome
DNA
gene
gamete
meiosis
sex chromosomes
allele
zygote
homozygous
heterozygous
genetic counseling
mutation
polygenic
pre-natal
SES
epigenesis
Main Ideas:
 Our genetic make-up can be defined as the basic set of directions for
development that we inherit from our parents.
 Genetics (Nature) and environment (Nurture) interact to determine our actual
development.
 Our inherited directions come to us in the form of chromosomes.
Chromosomes are in every cell in our bodies. Chromosomes are composed
of DNA; DNA is divided into functional segments called genes.
 Human beings have 46 chromosomes arranged in 23 pairs. We inherit half of
these from our fathers and half from our mothers. Since all the regular body
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cells contain 46 chromosomes, special reproductive cells (sex cells) have to
be formed with only half the number of chromosomes; this is accomplished by
a special process of cell division called meiosis.
The special reproductive cells produced by meiosis are called gametes. In
the female, the gamete is the egg; in the male, it is the sperm.
Twenty-two pairs of chromosomes are matching pairs called autosomes. The
twenty-third pair is made up of the X and Y chromosomes, the sex
chromosomes. A girl inherits two X chromosomes; a boy inherits an X and a
Y. The mother passes on only X chromosomes; the father can pass on an X
or a Y. Consequently, it is the father’s sperm that determines the sex of the
baby.
Most of the traits we inherit result from a combination of several genes, rather
than from just one gene. We inherit a mixture of traits from our mothers and
fathers, according to various patterns of meiosis and gene dominance.
Some genes require specific environmental influences to be expressed (in
effect, to “turn on”); some genes are never expressed.
Sometimes there are inherited problems or illnesses that are carried on the
genes, and pass from the parent to the child. Some changes to the gene –
good or bad – happen through mutation. Another type of genetic problem is
caused by accidents to the chromosomes that can happen during meiosis.
Down syndrome is an example of chromosomal accident.
Genetic counseling and pre-natal testing are two ways that couples can gain
important information about the likelihood of genetic problems.
The family is the most important environmental influence on the child’s
development. Family influence is both direct and indirect.
SES (socioeconomic status) and culture affect the family’s values and
relationships.
Poverty creates a trap for the family that is hard to escape and that may
ensnare a family for many generations. Poverty harms children’s
development in many ways. Of all the Western nations, the United States
has the highest percentage of extremely poor children.
Researchers are trying to expand our understanding of how the interplay
between genetics and environment works. This area of research is known as
epigenesis.
Berk Chapter 2: Genetic and Environmental Foundations 7e
Define phenotype:_______________________________________________________
Define genotype:________________________________________________________
GENETIC FOUNDATIONS
What is the function of chromosomes, what do they look like, and where are they
located?
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What are chromosomes made up of?
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What is the relationship of genes to chromosomes?
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When cells duplicate themselves to make more cells, the DNA is also copied in the new
cells.
This process is called ____________________________.
What are gametes and why are they necessary for human reproduction?
______________________________________________________________________
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Meiosis is a special process of cell duplication, different from mitosis. Why is meiosis
necessary?
______________________________________________________________________
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When egg and sperm unite, the new cell is called a _________________________.
Human chromosomes come in 23 pairs. 22 pairs match in size and amount of genetic
material – these are called autosomes. The chromosomes in the 23rd pair are called the
sex chromosomes – why? What role do they play in determining gender?
_____________________________________________________________________
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Why are fraternal twins called dizygotic?
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Briefly compare and contrast the genetic make-up of identical twins, fraternal twins and
non-twin siblings:________________________________________________________
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What is an allele?
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If a child inherits the allele for curly hair from both mother and father, that child is said to
be homozygous for that trait. Will that child have curly hair or not?_________________
If a child inherits the trait for curly hair from his mother, but not from his father, the child
is said to be heterozygous. Will that child have curly hair? (See Table 2.2 for help with
this question.) Briefly explain your answer:
________________________________________________________________________
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Why are serious diseases rarely carried on dominant alleles?
________________________________________________________________________
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What is incomplete dominance?
________________________________________________________________________
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What is X-linked inheritance?
________________________________________________________________________
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Why are male children more likely to be affected by an X-linked trait?
________________________________________________________________________
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What is a mutation, and what causes genes to mutate?
________________________________________________________________________
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What is polygenic inheritance? Give an example of a polygenic trait:
________________________________________________________________________
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One kind of mistake in a person’s genetic blueprint is the result of a gene mutating.
Chromosomal abnormalities are another kind of mistake. How do chromosomal
abnormalities occur? Give an example of a chromosomal abnormality.
________________________________________________________________________
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REPRODUCTIVE CHOICES
Genetic counseling is a process of information gathering and evaluation that helps
couples assess the risk of birth disorder if they have children. List 3 circumstances that
might cause a couple to seek genetic counseling:
_______________________________________________________________
_______________________________________________________________
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Several prenatal diagnostic tests are available to detect developmental problems before
birth. Not all problems that are identified by prenatal diagnostic tests can be corrected,
but some new medical procedures are expanding what can be done prenatally. List two
approaches that are currently being done, or that hold promise for the future:
________________________________________________
________________________________________________
What options are open for a couple who want to be parents, but find they cannot? (Name
2 or 3.)
_________________________________________________________________
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ENVIRONMENTAL CONTEXTS FOR DEVELOPMENT
Which “context” or environment has the broadest and most powerful influence in
development?
___________________________________________
List 4 things the family does for the developing child:
________________________________________________________________________
________________________________________________________________________
Give an example of a direct family influence, and an example of an indirect family
influence:
Direct:__________________________________________________________________
Indirect:_________________________________________________________________
What is SES?
__________________________________________________________________
Describe two differences given in your text for child rearing expectations / interactions
between higher SES parents and lower SES parents:
_______________________________________________________________________
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How does the text account for these differences?
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List your own ideas about 3 or 4 ways that poverty can have a negative impact on a
child’s development:
____________________________________________________
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List 4 groups within the U.S. population who are “hit hardest” by poverty:
________________________________, __________________________________,
________________________________, __________________________________.
Of all the Western nations, which one has the highest percentage of extremely poor
children?_____________________________________.
Your text states “Neighborhood resources have a greater impact on economically
disadvantaged than on well-to-do young people.” In your own words, explain several
ways that this can be true:
________________________________________________________________________
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Briefly outline several ways that family and neighborhood ties can help protect children
from the harmful effects of poverty:
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Culture shapes family life, school expectations, and community. What is the difference
between collectivist societies and individualistic societies?
________________________________________________________________________
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Which type predominates in the U.S.? _________________________________________
How does the text define public policy?
________________________________________________________________________
The text states that the U.S. does not rank well on key measures of child health and wellbeing. Cite one example of this:
________________________________________________________________________
What reasons might explain this? Give your own ideas on this, or give those suggested
by the text that you agree with:
________________________________________________________________________
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UNDERSTANDING THE RELATIONSHIP BETWEEN HEREDITY AND
ENVIRONMENT
It is now understood that our lifelong development is the result of the continual
interaction of genes and environmental factors. The action of genes causes changes in
our bodies and brains – but environmental factors turn genes on and off and can even
cause genes to change (mutate). What field of scientific inquiry is trying to discover how
nature and nurture contribute to the diversity of human traits and abilities?
________________________________________________________________________
Define epigenesis and give an example:
________________________________________________________________________
________________________________________________________________________
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Practice Quiz #2
1. Human chromosomes
a. store and transmit genetic information
b. come in 46 matching pairs
c. always come in XY pairs
d. are inherited from the mother only
2. ______________ is the duplication process of body cells, whereas ____________ is
the process of cell division through which gametes are formed.
a. meiosis; mutation
b. mutation; mitosis
c. meiosis; mitosis
d. mitosis; meiosis
3. How well does the U.S. rate on measures of child health and welfare?
a. ahead of all other nations
b. behind all other nations
c. very low on the list of industrialized nations
d. ahead of Canada and Great Britain
4. If a child displays a recessive characteristic, like red hair, then
a. each of the parents had to have at least one recessive gene
b. each of the parents had to have two recessive genes
c. at least one parent had to have a recessive gene
d. neither parent needed a recessive gene; the red hair could have “skipped” a
generation
5. The number of chromosomes in a gamete is _______ the number of chromosomes in a
zygote.
a. twice
b. half
c. the same
d. one-third
6. Amniocentesis
a. is the most widely used prenatal diagnostic technique
b. can be performed as early as 4 weeks after conception
c. uses a sample of the mother’s blood to look for genetic defects
d. uses high frequency sound waves to make a picture of the developing fetus
7. The pattern of genetic inheritance that accounts for traits such as intelligence, height
and personality is
a. polygenic
b. mutation
c. codominant
d. dizygotic
8. _____________ twins always have exactly the same genetic material.
a. fraternal
b. dizygotic
c. dominant
d. monozygotic
9. Which reason does NOT help to explain why American public policy on children’s
issues lags behind that of many other nations?
a. children cannot vote or speak out for themselves
b. American ideals stress self-sufficiency and independence
c. good social programs can be expensive
d. there is no need for such programs in the U.S.
10. The relationship between a mother and father in a family would be considered a/an
________ influence on the child.
a. direct
b. indirect
c. peripheral
d. indifferent