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psyc 130 > Nature Vs. Nurture > Flashcards

Nature Vs. Nurture Flashcards

1
Q

Nature and Nurture

A

Today, there is a
consensus that almost all
human characteristics are
influenced by both
genetics (i.e., nature) and
environment (i.e.,
nurture).

  • Genes and experience
    interact to produce
    unique outcomes.
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2
Q

Genes

A

units of
heredity that maintain
their composition from
one generation to the
next.

Genes come in pairs
because they are aligned
on chromosomes that
also come in pairs.

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3
Q

Chromosomes

A

are
double-helix strands of
deoxyribonucleic acid
(DNA).

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4
Q

DNA

A

contains four
nucleotide bases:
adenine, guanine,
cytosine, and thymine.
In a double-helix strand of
a chromosome, adenine
bonds to thymine and
guanine binds to cytosine

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5
Q

the genetic code

A

The sequence of
nucleotide bases

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6
Q

genotype

A

The genetic makeup of
an individual

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7
Q

phenotype

A

An individual’s
observable characteristics

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8
Q

autosomal
chromosomes

A

22 pairs of the
chromosomes and
contain autosomal
linked genes.

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9
Q

sex
chromosomes

A

are only a
pair in females.
- Sex chromosomes are
labelled X and Y.

  • Females have two X
    chromosomes and males
    have a X and a Y
    chromosome.
  • The X and Y
    chromosome differ in
    appearance and carry
    different genes.
  • Genes located on the
    sex chromosomes are
    called sex-linked genes.
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10
Q

X
chromosome

A

One example of a sexlinked gene is a gene that
codes for color vision

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11
Q

homozygous

A

If you have the same
version of a gene on both
chromosomes

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12
Q

heterozygous

A

If you have different versions of a
gene on both
chromosomes

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13
Q

alleles

A

Different versions of the
same gene

can be dominant
or recessive (in some
cases they can be
intermediate as well).

  • A dominant allele is
    expressed in either a
    homozygous or
    heterozygous condition.
  • A recessive allele is only
    expressed in the
    homozygous condition.
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14
Q

messenger
ribonucleic acid
(mRNA).

A

One of the strands of
DNA then serves as a
template for the
construction of a strand

RNA contains four
nucleotide bases:
adenine, guanine,
cytosine, and uracil.

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15
Q

Genetic Expression

A

During genetic
expression, the partial
section of the
chromosome that
contains the gene
unravels separating
the bonds between the
nucleotide bases.

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16
Q

transcription

A

The synthesis of mRNA
from DNA

17
Q

Translation

A

The ribosome uses the
strand of mRNA to
construct a protein. The
synthesis of a protein
from mRNA is called

18
Q

Proteins

A

chains of
amino acids that form
the structures of the body
and facilitate biological
functions (e.g., enzymes).

19
Q

codon

A

Three nucleotide bases
along a strand of mRNA

20
Q

transfer RNA
(tRNA)

A
  • A ribosome translates
    the messenger RNA by
    moving along the RNA
    bases. At each codon, it
    signals to a molecule to deliver the
    corresponding amino
    acid. The amino acid is then attached to a
    growing chain.
  • This process continues
    until the ribosome
    reaches a stop codon
    which signals that the
    protein is complete (see
    picture).
21
Q

Humans have how many genes?

A

approx.
20000 genes.

22
Q
  • The expression of genes
    is controlled by sections
    of DNA called
A

enhancers
or promotor regions
- Enhancers are regulated
by proteins called
transcription factors
that bind to enhancer
regions.
- The interaction between
transcription factors and
enhancers is regulated in
part by environmental
signals

23
Q

Mutations

A

Genes can undergo
spontaneous changes
called mutations.
- Genetic mutations can
then be passed to
offspring.
- A genetic mutation
typically does not
increase the fitness of the
individual who inherits it,
however, in some rare
cases it can (e.g.,
FOXP2 gene).
Two other types of
genetic mutations are
duplications and
deletions.

24
Q

Deletions

A

occur when
part of a DNA sequence
on a chromosome is
removed.

25
Q

Duplications

A

occur when
part of a DNA sequence is repeated.

Most deletions or
duplications are not
beneficial (e.g., Williams
Syndrome).
An example of a disorder
that is caused by a
duplication in the DNA
sequence is Fragile X
syndrome. It affects 1 in
4000 males and 1 in 8000
females.

26
Q

Fragile X Syndrome

A

caused by a
duplication in the
enhancer/promoter
region of the FMR1
gene (the Fragile X
Mental Retardation 1
gene) located on the X
chromosome.
- Normally, this region
contains 5 to 54
repeating CGG bases (i.e.,
cytosine, guanine,
guanine). For example,
CGGCGGCGGCGGCGGCG
GCGG.

The full mutation in
the promoter region of
the FMR1 causes the
gene to become
inactivated (i.e., the
gene is not
expressed).
- Therefore, an important
protein called the fragile
X mental retardation
protein (FMRP) is not
synthesized.
- Lack of the FMRP causes
the symptoms associated
with Fragile X syndrome.

27
Q

a FMR1 gene
premutation.

A

Some people have a
version of this gene
that contains 55 to 200
repeats of the CGG
segment.

28
Q

Epigenetics

A

The relatively new
field of epigenetics
explores changes in
genetic expression as
the result of
environmental
influences.

These changes in
genetic expression occur
without changes to the
underlying DNA base
sequence.
- Epigenetic changes
provide a mechanism
through which genes and
experience interact.

29
Q

histone
remodeling.

A

epigenetic
mechanism

DNA wraps around
proteins called histones
(think of string wrapped
around a ball).
- DNA wrapped around
histones is called
chromatin.
- For a gene to be
expressed, DNA must
partially unwrap from the
histones.
- When DNA is wrapped
tightly around the
histones, genes are
unable to be expressed.
- When DNA is unwound
from the histones, genes
can be expressed.
- Experiences (e.g.,
feeling socially isolated)
can alter the chemical
environment in a cell,
which can cause histone
remodeling and changes
in genetic expression.

30
Q

DNA
methylation

A
  • DNA methylation occurs
    when methyl groups
    (CH3) bind to the
    promotor region of a
    gene.
  • Methylation typically
    causes a gene to be
    turned off (but not
    always).
  • Methyl groups typically
    bind to cytosine bases.
  • In fact, this is what
    occurs in Fragile X
    syndrome. The repeated
    CGG segment becomes
    hypermethylated, turning
    off the FMRI gene.
    Many types of
    environmental factors
    that can promote
    epigenetic changes.
31
Q

transgenerational
epigenetics.

A

epigenetic changes can
be passed from parents
to offspring.

32
Q

Behavioral Genetics

A

the study of genetic
influences on individual
differences in
psychological
characteristics and
behavior.

33
Q

Molecular genetics

A

focused on identifying the
specific genes associated
with psychological
characteristics and
behaviors (e.g., which
genes are associated with
psychopathy?).

34
Q

A heritability estimate

A

provides a percentage of
the amount of trait
variation in a population
that can be accounted for
by differences in
genetics.
- Heritability estimates
range from zero to 100%.
- Heritability estimates
cannot be applied to
specific individuals within
the population that was
used to calculate it.

A heritability estimate
can only be applied to
the population that
was used to calculate
it because it is directly
influenced by the
degree of genetic and
environmental
variability that exists
within a population.

35
Q

How do behavioral
geneticists calculate
heritability estimates?

A
  • Twin studies compare
    the degree of similarity
    on a trait between
    monozygotic twins and
    dizygotic twins.
  • The higher the degree of
    similarity on a trait
    between monozygotic
    twins compared to
    dizygotic twins, the
    higher the heritability
    estimate will be.
    Studies of heritability
    estimates using Western
    samples have shown that
    differences in almost
    every trait and behavior
    in psychology has a
    substantial genetic
    influence (i.e., between
    40 to 80 percent).

psyc 130 (5 decks)

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