3.1
Psychological researchers study genetics in order to better understand the biological factors that contribute to certain
behaviors.
Sickle-cell anemia is a genetic condition in which red blood cells, which are normally round, take on a crescent-like
shape
-The changed shape of these cells affects how they function: sickle-shaped cells can clog blood vessels and block blood
flow, leading to high fever, severe pain, swelling, and tissue damage.
-Many people die from sickle cell anemia at a young age
Sickle-cell carriers have one copy of the sickle-cell gene but do not have full-blown sickle-cell anemia.
-They experience symptoms only if they are severely dehydrated or are deprived of oxygen
-Carriers are thought to be immune to malaria (an often deadly disease that is widespread in tropical climates) because
changes in their blood chemistry and immune functioning prevent the malaria parasite from having its effects
-People with two copies of the sickle-cell gene do not provide immunity to malaria.
Charles Darwin's theory of evolution by natural selection states that organisms that are better suited for their
environment will survive and reproduce, while those that are poorly suited for their environment will die off.
Two Perspectives on Genetics and Behavior
Evolutionary psychology focuses on how universal patterns of behavior and cognitive processes have evolved over time.
- Variations in cognition and behavior would make individuals more or less successful in reproducing and passing those
genes on to their offspring.
Behavioral geneticists study how individual differences arise, in the present, through the interaction of genes and the
environment.
,Genetic Variation
Genetic variation, the genetic difference between individuals, is what contributes to a species’ adaptation to its
environment.
-In humans, genetic variation begins with an egg, about 100 million sperm, and fertilization.
The egg and the sperm each contain 23 chromosomes. Chromosomes are long strings of genetic material known as
deoxyribonucleic acid (DNA).
-DNA is a helix-shaped molecule made up of nucleotide base pairs.
-In each chromosome, sequences of DNA make up genes that control or partially control a number of visible
characteristics, known as traits, such as eye color, hair color, and so on.
-A single gene may have multiple possible variations, or alleles.
-An allele is a specific version of a gene.
When a sperm and egg fuse, their 23 chromosomes combine to create a zygote with 46 chromosomes (23 pairs). Each
parent contributes half the genetic information carried by the offspring
A person’s genotype is the genetic makeup of that individual.
Phenotype refers to the individual’s inherited physical characteristics, which are a combination of genetic and
environmental influences
Genotype refers to the genetic makeup of an individual based on the genetic material (DNA) inherited from one’s genetic
contributors. Phenotype describes an individual’s observable characteristics, such as hair color, skin color, height, and
build.
Most traits are controlled by multiple genes, but some traits are controlled by one gene.
-A characteristic like cleft chin, for example, is influenced by a single gene from each parent.
,Which means that having the dominant allele either from one parent (Bb) or both parents (BB) will always result in the
phenotype associated with the dominant allele.
-For example, smooth chin is a recessive trait, which means that an individual will only display the smooth chin phenotype
if they are homozygous for that recessive allele (bb).
When someone has two copies of the same allele, they are said to be homozygous for that allele.
When someone has a combination of alleles for a given gene, they are said to be heterozygous
A Punnett square is a tool used to predict how genes will interact in the production of offspring. The capital B represents
the dominant allele, and the lowercase b represents the recessive allele.
In sickle cell anemia, heterozygous carriers can develop blood resistance to malaria infection while those who are
homozygous have a potentially lethal blood disorder.
Sickle-cell anemia is just one of many genetic disorders caused by the pairing of two recessive genes.
, Phenylketonuria (PKU) is a condition in which individuals lack an enzyme that normally converts harmful amino acids
into harmless byproducts.
-If someone with this condition goes untreated, they will experience significant deficits in cognitive function, seizures, and
an increased risk of various psychiatric disorders.
-PKU is a recessive trait so each parent must have at least one copy of the recessive allele in order to produce a child
with the condition
PKU, a genetic disorder discussed earlier, causes a reduction in myelin and abnormalities in white matter cortical and
subcortical structures.
Most traits are polygenic: controlled by more than one gene.
-Height is one example of a polygenic trait, as are skin color and weight.
A mutation is a sudden, permanent change in a gene. While many mutations can be harmful or lethal, once in a while, a
mutation benefits an individual by giving that person an advantage over those who do not have the mutation.
The theory of evolution asserts that individuals best adapted to their particular environments are more likely to reproduce
and pass on their genes to future generations.
-In order for this process to occur, there must be competition, there must be variability in genes that allow for variation in
adaptability to the environment.
-If a population consisted of identical individuals, then any dramatic changes in the environment would affect everyone in
the same way, and there would be no variation in selection.
-Diversity in genes and associated traits allows some individuals to perform slightly better than others when faced with
environmental change.
Human Diversity
When we focus strictly on biology, race becomes a weak construct. Many scientists began to argue that race was not a
useful variable in genetic research and that its continued use represents a potential source of confusion and harm.
Psychological researchers study genetics in order to better understand the biological factors that contribute to certain
behaviors.
Sickle-cell anemia is a genetic condition in which red blood cells, which are normally round, take on a crescent-like
shape
-The changed shape of these cells affects how they function: sickle-shaped cells can clog blood vessels and block blood
flow, leading to high fever, severe pain, swelling, and tissue damage.
-Many people die from sickle cell anemia at a young age
Sickle-cell carriers have one copy of the sickle-cell gene but do not have full-blown sickle-cell anemia.
-They experience symptoms only if they are severely dehydrated or are deprived of oxygen
-Carriers are thought to be immune to malaria (an often deadly disease that is widespread in tropical climates) because
changes in their blood chemistry and immune functioning prevent the malaria parasite from having its effects
-People with two copies of the sickle-cell gene do not provide immunity to malaria.
Charles Darwin's theory of evolution by natural selection states that organisms that are better suited for their
environment will survive and reproduce, while those that are poorly suited for their environment will die off.
Two Perspectives on Genetics and Behavior
Evolutionary psychology focuses on how universal patterns of behavior and cognitive processes have evolved over time.
- Variations in cognition and behavior would make individuals more or less successful in reproducing and passing those
genes on to their offspring.
Behavioral geneticists study how individual differences arise, in the present, through the interaction of genes and the
environment.
,Genetic Variation
Genetic variation, the genetic difference between individuals, is what contributes to a species’ adaptation to its
environment.
-In humans, genetic variation begins with an egg, about 100 million sperm, and fertilization.
The egg and the sperm each contain 23 chromosomes. Chromosomes are long strings of genetic material known as
deoxyribonucleic acid (DNA).
-DNA is a helix-shaped molecule made up of nucleotide base pairs.
-In each chromosome, sequences of DNA make up genes that control or partially control a number of visible
characteristics, known as traits, such as eye color, hair color, and so on.
-A single gene may have multiple possible variations, or alleles.
-An allele is a specific version of a gene.
When a sperm and egg fuse, their 23 chromosomes combine to create a zygote with 46 chromosomes (23 pairs). Each
parent contributes half the genetic information carried by the offspring
A person’s genotype is the genetic makeup of that individual.
Phenotype refers to the individual’s inherited physical characteristics, which are a combination of genetic and
environmental influences
Genotype refers to the genetic makeup of an individual based on the genetic material (DNA) inherited from one’s genetic
contributors. Phenotype describes an individual’s observable characteristics, such as hair color, skin color, height, and
build.
Most traits are controlled by multiple genes, but some traits are controlled by one gene.
-A characteristic like cleft chin, for example, is influenced by a single gene from each parent.
,Which means that having the dominant allele either from one parent (Bb) or both parents (BB) will always result in the
phenotype associated with the dominant allele.
-For example, smooth chin is a recessive trait, which means that an individual will only display the smooth chin phenotype
if they are homozygous for that recessive allele (bb).
When someone has two copies of the same allele, they are said to be homozygous for that allele.
When someone has a combination of alleles for a given gene, they are said to be heterozygous
A Punnett square is a tool used to predict how genes will interact in the production of offspring. The capital B represents
the dominant allele, and the lowercase b represents the recessive allele.
In sickle cell anemia, heterozygous carriers can develop blood resistance to malaria infection while those who are
homozygous have a potentially lethal blood disorder.
Sickle-cell anemia is just one of many genetic disorders caused by the pairing of two recessive genes.
, Phenylketonuria (PKU) is a condition in which individuals lack an enzyme that normally converts harmful amino acids
into harmless byproducts.
-If someone with this condition goes untreated, they will experience significant deficits in cognitive function, seizures, and
an increased risk of various psychiatric disorders.
-PKU is a recessive trait so each parent must have at least one copy of the recessive allele in order to produce a child
with the condition
PKU, a genetic disorder discussed earlier, causes a reduction in myelin and abnormalities in white matter cortical and
subcortical structures.
Most traits are polygenic: controlled by more than one gene.
-Height is one example of a polygenic trait, as are skin color and weight.
A mutation is a sudden, permanent change in a gene. While many mutations can be harmful or lethal, once in a while, a
mutation benefits an individual by giving that person an advantage over those who do not have the mutation.
The theory of evolution asserts that individuals best adapted to their particular environments are more likely to reproduce
and pass on their genes to future generations.
-In order for this process to occur, there must be competition, there must be variability in genes that allow for variation in
adaptability to the environment.
-If a population consisted of identical individuals, then any dramatic changes in the environment would affect everyone in
the same way, and there would be no variation in selection.
-Diversity in genes and associated traits allows some individuals to perform slightly better than others when faced with
environmental change.
Human Diversity
When we focus strictly on biology, race becomes a weak construct. Many scientists began to argue that race was not a
useful variable in genetic research and that its continued use represents a potential source of confusion and harm.
