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Chapter 6

PSYB30H3 Chapter Notes - Chapter 6: Human Genome Project, Twin Study, Noncoding Dna


Department
Psychology
Course Code
PSYB30H3
Professor
Lisa Fiksenbaum
Chapter
6

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Personality
Part 2: The Biological Domain
Ch. 6 Genetics & Personality
The Biological Domain
The “
biological domain
” refers to those physical elements and biological systems
within our bodies that inuence or are inuenced by our behaviours, thoughts, and
feelings.
For example, one type of physical element with our bodies that may inuence
our
personalities
is our genes.
Our genetic makeup determines whether our hair is curly or straight, whether
our eyes are blue or brown, and whether we have large, heavy bones, or a slight
build.
Our genetic makeup inuences our
personality
.
Another area in which biology and
personality
intersect is in the physiological
systems, such as the brain or peripheral nervous system.
Genetics and Personality
The
Jim Twins
are identical twins separated at birth and raised in di#erent adoptive
families.
These twins displayed a set of similarities; both weight 180 & were 6 ft., they
both had been married twice, their jobs were similar, both drank the same beer
and smoked the same cigarette brand, both su#ered from the same kind of
headache syndrome, and both had the same habit of biting +nger nails.
Both they also had some di#erences, such as one was a better writer and one
was a better speaker, they wore their hair di#erently.
*(The "Jim twin”: are very similar despite having been separated at birth)*
The Human Genome
Genome: The complete set of genes an organism possess the human genome
contains somewhere between 20,000 and 30,000 genes.
All these
genes
are located on
23 pairs
of
chromosomes
.
Each person
inherits one set
of each pair of
chromosomes
from the
mother
and one set from the father.
Each
gene
consists of long sequences of DNA molecules.
The
nucleus
of each
cell
within
the body contains two complete sets of the
human genome
, one from the mother and one from the father.
The only exceptions are
red blood cells
, which do not contain any
genes
, and
female egg cells
and
male sperm cells
, each of which contains only one copy of
the
human genome
.
B/c the body contain roughly 100 trillion
cells
, and each of us roughly 100 trillion
copies of our
genome
within our bodies.
The
Human Genome Project
is a multibillion-dollar research endeavor that is
dedicated to sequence the entire genome— that is, to identifying the particular
sequence of
DNA molecules
in the human species.
Identifying the sequence of
DNA molecule
does not mean identifying all the
functions of these D
NA molecules
.
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*(The goal of the Human Genome Project is to: identify the particular sequence of
DNA molecules in humans)*
*(The Human Genome Project has: identi+ed the sequence of DNA molecules in
humans)*
Two speci+c +ndings have been turning
standard assumptions
about the
human
genome
on its head:
FIRST, although the number of
genes
humans possess is similar to the number
of
genes
estimated for mice & worms, the “manner” in which
human genes
get
decoded into
proteins
turns out to be more variable than in other species.
SECOND, these
protein-coding genes
make up roughly 2% of the
human
genome
.
Many parts of the other 98% of the
DNA
in the human
chromosomes
used to
known, as genetic junk b/c scientists believed that these parts
were
functionless residues
that
served no purposes
.
Now this “
junk DNA
” is not junk at all but rather parts of these chucks of
DNA
have an impact on humans, potentially a#ecting everything from person’s
physical size to personality/
oThese hidden layers of complexity in the human genome “
pseudogenes
& “
riboswitches
”.
Genetic Junk: the 98% of the DNA in human chromosomes that aren’t protein-coding
genes; scientists believe that these parts were functionless residue. Recent studies
have shown that these proportions of DNA may a#ect everything from a person’s
physical size to personality, thus adding to the complexity of the human genome.
Controversy About Genes & Personality
Researchers in this +eld attempt to determine the degree to which individual
di#erences in
personality
are caused by
genetic
and
environmental di#erences
.
Scienti+c reports on
behavioural genetic studies
often make headlines and
cover stories.
Some media sources are proposing “
designer babies
”, where parents select
from a genetic checklist the characteristics they would like in their children.
These ideas are controversial b/c they suggest that
genetic di#erences
among individuals
, rather than di#erences in parental socialization or
personal experience, are responsible for shaping the core features of
human
personality
.
Many people worry that +ndings from
behavioural genetics
will be used (or misused)
to support certain political agendas.
If the scientists trace a
behaviour pattern
or
personality trait
to a
genetic
component
, some people worry that such +ndings might lead to pessimism
about the possibilities for change.
Fears about genetic research:
Genetic research will lead to the development of "designer" babies.
If criminal behavior is genetic then attempts at rehabilitation will be fruitless.
Genetic research will marginalize research in other areas of psychology.
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*(Which one of the following is NOT one of the fears about genetic research? Decoding
genetic di#erences will reveal complexities in human nature)*
Eugenics is the notion that we can design the future of the human species by
fostering the reproduction of persons with certain traits and by discouraging the
reproduction of persons without those traits.
Many people are concerned that +ndings from
genetic studies
might be used to
support programs intended to prevent some individuals from reproducing
or,
even worse, to bolster the cause of those who would advocate that
some
people be eliminated in order to create a
master race
”.
*(The idea that people with "desirable" characteristics should be encouraged to have
children while "less desirable" people should be discouraged from having children is
called: eugenics)*
Modern psychologists who study the
genetics of personality
are typically extremely
careful in their attempts to educate others, about the use and potential misuse of
their +ndings.
Eugenics: The notion that the future of the human race can be inuenced by Buss. It
is based on the idea that certain personality traits may evoke consistent responses
from the environment, particularly the social environment.
Goals of Behavioural Genetics
Most
psychologists who study genetics
: are interested in the causes of individual
di#erences.
Geneticists focus on the key question, “What causes some individuals to be tall
and others to be short?”
In principle, there can be a
variety of causes of individual height di#erences
.
Di#erences in diet while growing up, for example, can cause di#erences in
height among people.
Genetic di#erences
can also account for some of the di#erences in height.
One of the central goals of
genetic research
is to determine the % of an
individual
di#erence
that can be attributed to
genetic di#erences
and the % due to
environmental di#erences
.
In the
case of height
, both
environmenta
l and
genetic factors
are important.
Children tend to resemble their parents in height.
And
genetic research
has con+rmed that roughly 90% of the
individual
di#erences
in height are indeed due to
genetic di#erences
.
The
environment
, which contributes 10% to
individual di#erences
in height, is
far from trivial.
In the United States,
average adult height has increased in the entire population by
roughly 2 inches
over the past century, most likely
due to increases in the nutritional
value
of the food eaten.
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