psy exam 3 alex important

DARWINIAN THEORY AND NATURAL SELECTION

Darwinian Theory

Darwin's theory that evolution occurs through natural selection and differential reproductive success.

Natural Selection

Process where organisms with advantageous inherited traits are more likely to survive and reproduce.

Inherited Traits

Characteristics passed from parents to offspring through genes.

Differential Reproductive Success

Some individuals reproduce more successfully than others, passing their traits to future generations.

Survival of the Fittest

Individuals with traits that improve reproductive success are more likely to pass those traits on; it does not necessarily mean physical strength.

Evolution by Natural Selection

Over generations, advantageous inherited traits become more common in a population.

Genetic Variation

Differences in inherited traits among individuals within a population.

EPIGENETIC MODIFICATION

Epigenetics

Changes in gene expression without changing the actual DNA sequence.

DNA Methylation

Addition of methyl groups to DNA that usually decreases or turns off gene expression.

Histone Modification

Chemical changes to histone proteins that make DNA more or less accessible for gene expression.

Methyl Groups

Chemical groups that attach to DNA during DNA methylation and often reduce gene expression.

Histones

Proteins that DNA wraps around to form nucleosomes.

Gene Expression

Process by which information in a gene is used to make a functional product.

DNA Methylation vs. Histone Modification

DNA methylation usually decreases gene expression, while histone modification changes how accessible DNA is.

Intergenerational Epigenetic Effects

Environmental experiences affect the next generation or other directly exposed generations.

Transgenerational Epigenetic Effects

Epigenetic effects continue into generations that were not directly exposed to the original environmental influence.

Intergenerational vs. Transgenerational

Intergenerational affects directly exposed generations, while transgenerational continues into generations not directly exposed.

Environmental Influence on Epigenetics

Experiences such as stress, nutrition, and environmental conditions can influence gene expression.

Identical Twin Epigenetic Study

Identical twins share nearly identical DNA but can develop different epigenetic patterns due to environmental experiences.

Dutch Hunger Winter Study

Research showing that prenatal famine exposure was associated with long-lasting changes in DNA methylation.

IGF2

Insulin-like growth factor 2, a gene involved in growth and development that was examined in the Dutch Hunger Winter study.

GHRELIN AND ENERGY INTAKE

Ghrelin

The hunger hormone produced primarily by the stomach that increases appetite and food intake.

Hunger Hormone

Ghrelin; signals the brain that the body needs food.

Ghrelin Function

Stimulates hunger-related neurons in the hypothalamus and encourages food intake.

Ghrelin Levels

Generally rise before meals and fall after eating.

Preprandial

Occurring before a meal; ghrelin levels typically increase before eating.

Postprandial

Occurring after a meal; ghrelin levels typically decrease after eating.

Ghrelin and the Hypothalamus

Ghrelin helps activate hunger-related neurons, including AgRP/NPY neurons.

Ghrelin Study

Researchers measured plasma ghrelin levels 38 times over 24 hours in healthy subjects and found levels rose before meals and fell after meals.

NEURONS THAT CONTROL FOOD INTAKE

Arcuate Nucleus (ARC)

Region of the hypothalamus containing two major groups of neurons that regulate hunger and fullness.

AgRP/NPY Neurons

Orexigenic neurons that increase hunger and food intake.

POMC Neurons

Anorexigenic neurons that decrease hunger and food intake.

AgRP

Agouti-related peptide; blocks melanocortin receptors and promotes eating.

NPY

Neuropeptide Y; chemical messenger that stimulates appetite and food intake.

POMC

Pro-opiomelanocortin; precursor protein processed into peptides including alpha-MSH that suppress appetite.

CART

Cocaine- and amphetamine-regulated transcript; associated with reduced food intake.

GABA

Inhibitory neurotransmitter released by AgRP neurons that decreases the activity of other neurons.

Alpha-MSH

Alpha-melanocyte-stimulating hormone; activates melanocortin receptors to reduce appetite.

Melanocortin Receptors

Receptors involved in regulating appetite and energy balance.

AgRP Neurons

Neurons located in the arcuate nucleus that promote hunger and increase food intake.

AgRP Neuron Function

Become active when energy levels are low, respond to hunger signals such as ghrelin, and promote eating.

AgRP and NPY

AgRP blocks melanocortin receptors while NPY stimulates appetite; both promote food intake.

POMC and CART

Signals associated with reducing hunger and suppressing food intake.

Orexigenic Neurons

Neurons that promote hunger and increase food intake.

Anorexigenic Neurons

Neurons that suppress hunger and decrease food intake.

AgRP vs. POMC

AgRP increases hunger and food intake, while POMC decreases hunger and food intake.

GWAS AND GENETICS

GWAS

Genome-wide association study; research method used to identify genetic variations associated with traits or diseases.

Genome-Wide Association Study

Examines genetic variations across many individuals to find associations with particular traits.

GWAS Process

Researchers collect DNA from many individuals, compare genetic variations, and identify variations associated with a particular trait.

GWAS Example

Researchers compare individuals with different body weights to identify genetic variations associated with obesity.

GWAS Limitation

Identifies associations between genetic variations and traits but does not necessarily prove that a variation causes the trait.

SNP

Single nucleotide polymorphism; a difference in one nucleotide in the DNA sequence.

Single Nucleotide Polymorphism

A genetic variation involving one DNA building block.

SNP vs. Epigenetics

SNPs change the DNA sequence, while epigenetics changes gene expression without changing the DNA sequence.

Genetic Variation

Differences in DNA sequences between individuals that can influence traits.

UMAMI TASTE

Umami

The savory or meaty basic taste commonly associated with glutamate.

Glutamate

An amino acid associated with umami taste.

Umami Receptors

T1R1 and T1R3 work together to detect umami taste.

T1R1/T1R3

Receptor combination responsible for detecting umami taste.

Umami Examples

Meat, mushrooms, Parmesan cheese, and soy sauce.

Umami Function

Helps identify savory foods and amino acids associated with protein-rich foods.

INFANT TASTE RESPONSES

Sweet Taste Response in Infants

Infants generally show positive facial expressions, increased sucking, and greater consumption when given sweet solutions.

Bitter Taste Response in Infants

Infants generally show negative facial expressions, nose wrinkling, and rejection responses when given bitter solutions.

Sweet vs. Bitter in Infants

Sweet solutions generally produce acceptance responses, while bitter solutions generally produce avoidance responses.

Measuring Infant Taste Responses

Researchers measure how much liquid infants consume, observe sucking behavior, and examine facial expressions.

Appetitive Taste Response

Positive response to food, such as tongue protrusions or increased acceptance.

Aversive Taste Response

Negative response to food, such as gaping, rejection, or avoidance.

HYPOTHALAMUS AND FEEDING LESIONS

Lateral Hypothalamus (LH)

Traditionally known as the hunger or feeding center of the brain.

Lateral Hypothalamus Lesion

Damage can decrease food intake and cause animals to stop eating and lose weight.

Ventromedial Hypothalamus (VMH)

Traditionally known as the satiety or fullness center of the brain.

Ventromedial Hypothalamus Lesion

Damage can cause increased food intake, overeating, and weight gain.

Lateral vs. Ventromedial Hypothalamus

Lateral hypothalamus damage decreases eating, while ventromedial hypothalamus damage increases eating.

Lateral Hypothalamus Memory Trick

Lateral = Less eating when damaged.

Ventromedial Hypothalamus Memory Trick

Ventromedial = More eating when damaged.

Satiety

Feeling of fullness that helps stop eating.

Lesion

An area of damaged or destroyed brain tissue.

SNPs VS. EPIGENETICS

SNP

A variation in one nucleotide of the DNA sequence.

Epigenetics

Changes in gene expression without changing the DNA sequence.

SNPs and DNA

SNPs change the actual DNA sequence.

Epigenetics and DNA

Epigenetics changes how genes are used without changing the underlying DNA sequence.

SNP vs. Epigenetics Comparison

SNPs are genetic sequence differences, while epigenetics involves chemical modifications that influence gene expression.

SNP Inheritance

SNPs can be inherited from parents.