PSYCH 111: Genetics + Evolution

DNA (deoxyribonucleic acid)

a large, double-helix molecule containing genetic information written in a language using four bases (A, G, C, T).

• Portions contain genes.

behavioral genetics

The study of how heritability and genetics influence behavior.

monozygotic (MS) twins

Also known as identical twins. Twins that develop from one sperm and one egg that divide in the womb, so the twins share the same DNA.

genetic determinism

The philosophy that our genes (nature) determine to a large degree our physical and mental traits. The idea often discounts the influence of experiences.

acetyl groups

Molecules that loosen DNA, allowing for transcription.

positive eugenics

The idea of promoting reproduction in humans with "good" genes.

dizygotic (DZ) twins

Also known as fraternal twins. Twins that share the same womb but are no more related than brothers and sisters. They share on average 50% of their genes.

CRISPR-Cas9

A revolutionary technique for genetically modifying organisms that is accurate and relatively inexpensive.

Charles Darwin

Researcher and naturalist who lived in the 1800s who developed the theory of natural selection to explain the evolution of organisms.

concordances

Statistics that report the probability of related people developing the same neuropsychiatric disorder.

Down syndrome

A genetic disorder where a person has an extra twenty-first chromosome, leading to specific physical and mental characteristics.

genotype

The allele configuration on chromosomes as either homozygous or heterozygous.

• are created when an allele from the male sperm and female egg come together.

halorhodopsin (NpHR)

A light-sensitive protein used in optogenetics research that opens Cl- channels when struck by yellow or orange light, causing an inhibition of neuron activity.

genetic engineering

A technique for changing the genetic makeup of an organism by removing genes or inserting genes from other organisms.

nature vs. nurture argument

The idea genes are competing against environment and socialization for the influence on physical and behavioral traits. A better way of thinking about it is that they work together.

phenotype

The physical or behavioral representation of a gene.

homozygous

A genotypic configuration of allele where there are either two dominant or two recessives together.

carrier testing

A genetic testing for parents to determine if they carry recessive alleles for genetic disorders such as Tay-Sachs, sickle cell disorder, or cystic fibrosis.

heterozygous

A genotypic configuration where there is one dominant and one recessive allele together.

allele

Two forms of the same gene. One is found on each pair of chromosomes and so are from each parent

• can be dominant, recessive, or a combination of both.

phenylketonuria (PKU)

A monogenic homozygous recessive disorder where a person cannot convert phenylalanine to tyrosine. Causes severe brain damage unless the individual is put on a strict diet.

• a good example of nature and nurture.

transgenic organisms

A genetically modified organism often used in research to investigate the influence of specific genes.

reward deficiency hypothesis

A hypothesis that sensation-seekers have chronically lower levels of dopamine and so seek out risk or sensations to elevate the reinforcing nature of dopamine.

genetically modified organism (GMO)

An organism (plants, animals, fungi, bacteria) that has had its genome changed.

eugenics

A movement in the early part of the 1900s that was motivated to improve the human race.

• misappropriated the theory of evolution and intelligence testing for their discriminatory agenda.

pharmacogenomics

A method of using genetic testing to determine the best pharmacological treatments for diseases.

law of independent assortment

Mendel’s second law of inheritance that alleles for different genes are passed on to offspring independently of each other.

theory of natural selection

Charles Darwin’s theory of how organisms evolved based on five basic postulates: variation, over reproduction, competition, advantage, and modification by descent.

negative eugenics

The idea of preventing reproduction in humans with ‘bad’ genes. This led to discrimination and sterilization in the United States and mass murder in Nazi Germany.

proximal causes

The influences on behavior that an animal, including humans, experiences within its own life, such as learning.

methyl groups

Molecules that act as tags to DNA that affect the expression of genes.

• play an important role in epigenetics.

law of segregation

Gregor Mendel’s first law of inheritance, that organisms have two alleles for each gene and the alleles separate when making sex cells like sperm and eggs.

ultimate causes

The influences on behavior that are thought to have long-term adaptive functions and so are selected for during evolution.

• often refer to genetics or natural causes.

Human Genome Project (HGP)

a massive scientific collaborative endeavor to sequence the entire human genome, containing approximately 3 billion base pairs.

epigenetics

study of how environmental experiences contribute to the expression of genes.

• factors can be transmitted from one generation to the next without changes in DNA.

Immigration Act of 1924

Pressured by eugenicists, Congress passed an act that limited immigration of people from Eastern and Southern Europe and Asia because it was thought that these people contained inferior genes.

gene targeting

A method of changing or removing specific genes without adding new genes. A technique often used in research.

cell-free fetal DNA testing

a prenatal test that can detect chromosomal abnormalities in a fetus as early as ten weeks by testing the mother’s blood.

knockout mice

Commonly used animal models for research in medicine and neuroscience where a gene of interest is identified and made inactive or deleted.

comparative psychology

A field of psychology that compares cognition, memory, and learning across different species of animals.

channelrhodopsin (ChR2)

A light-sensitive protein used in optogenetics research that opens Na+ channels when struck by blue light, causing an increase in neuron activity.

preimplantation genetic diagnosis (PGD)

A way of testing for genetic disorders. Following in vitro fertilization, a cell is removed at the eight-cell stage and tested for disorders and carriers of recessive alleles.

gene

A section of DNA that codes for creating proteins.

• often come in two forms called alleles.

heritability

A statistical term relating the influence of genetics and environment on traits. Twin and family studies are often used to determine this

optogenetics

A genetic engineering technique where genes for photosensitive receptors are spliced into neurons using viruses. The neurons can then be excited or inhibited by light.