3313 Genetics & Brain Development Vocabulary

Genotype

– An organism’s genetic makeup.

Phenotype

– Observable traits influenced by genotype and environment.

Heritability

– The proportion of trait variation in a population due to genetics.

Concordance

– Degree of similarity in a trait between relatives (e.g., twins).

Monozygotic Twins (MZ)

– Identical twins; share all genes.

Dizygotic Twins (DZ)

– Fraternal twins; share about 50% of genes.

Family Studies

– Examine relatives to determine genetic influence.

Adoption Studies

– Compare adopted children to biological vs. adoptive parents.

Linkage Studies

– Identify genes linked to traits/diseases through inheritance patterns.

Transgenic Model (KnockIn)

– Organism with an inserted foreign gene.

KnockOut / Knockdown

– Deactivation or removal of a gene to study its function

Optogenetics

– Uses light to control genetically modified neurons expressing opsins.

CRISPR-Cas9

– Gene-editing technology for cutting and modifying specific DNA sequences.

Retroviral Gene Therapy

– Uses viruses to insert therapeutic genes into cells.

Mutation

–Permanent DNA change; can be harmful, neutral, or beneficial.

SNP (Single Nucleotide Polymorphism) –

One-base DNA change (e.g., APOE gene variants).

CNV (Copy Number Variation)

– Variation in number of copies of a gene segment.

APOE Gene

– Gene associated with Alzheimer’s disease risk.

Huntington’s Disease

– Genetic disorder caused by extra CAG repeats (CNV).

Down Syndrome (Trisomy 21)

– Genetic disorder with an extra chromosome 21.

Epigenetics

– Study of gene expression regulation without DNA sequence change.

Histone Modification

– Chemical changes to histone proteins that affect DNA accessibility.

DNA Methylation

– Addition of methyl groups that silences gene expression.

Non-Coding RNA

– RNA molecules that regulate gene expression without making proteins.

Gene Silencing

– Inhibition of gene expression by epigenetic mechanisms.

BPA (Bisphenol A)

– Chemical that affects gene expression in animal models (e.g., agouti mice).

Serotonin Transporter Gene (5-HTT)

– Variation interacts with stress to influence depression risk.

Neural Tube

– Embryonic structure forming the brain and spinal cord.

Neurogenesis

– Formation of new neurons from progenitor cells.

Migration

– Movement of neurons to final positions guided by radial glia.

Differentiation

– Specialization of neurons into sensory, motor, or interneuron types.

BMP Protein

– Dorsal signaling molecule that promotes sensory neuron development.

Sonic Hedgehog Protein (Shh)

– Ventral signal promoting motor neuron development.

Hox Genes

– Genes controlling anterior–posterior (rostral–caudal) patterning.

Apoptosis

– Programmed cell death; shapes neural circuits.

Synaptogenesis

– Formation of synapses between neurons.

Synaptic Pruning

– Elimination of weak or unused synapses to refine networks.

Neurotrophins

– Molecules that promote neuron survival and growth.

Growth Cone

– Structure at tip of developing axon guiding its pathfinding.

Filopodia / Lamellipodia

– Extensions of growth cones that sense the environment.

Ectoderm

– Outer embryonic layer; forms nervous system and skin.

Mesoderm

– Middle layer; forms muscles and connective tissue.

Endoderm

– Inner layer; forms internal organs.

Ventricular Zone

– Lining of neural tube where new neurons are born.

Inside-Out Pattern

– Cortical neurons form deeper layers first, superficial layers last.

Myelination

– Formation of myelin sheath; improves signal conduction.

Synaptic Density

– Number of synapses; peaks in childhood, declines in adolescence.

Prefrontal Cortex

– Final brain region to fully mature (early adulthood).

Limbic System

– Emotional center; matures before prefrontal cortex, influencing teen risk

Plasticity

– Brain’s ability to change with experience and learning.

Critical Period

– Window of development when experience strongly shapes neural circuits.

Long-Term Potentiation (LTP)

– Strengthening of synapses with repeated use.

Enriched Environment

– Stimulating conditions that promote dendritic and synaptic growth.

Neurogenesis (Adult)

– Continued formation of neurons, especially in hippocampus.

Cognitive Reserve

– Brain’s resilience against age-related decline or damage.

Medial Temporal Lobe

– Region crucial for memory; vulnerable in aging.

Microcephaly

– Abnormally small brain/head size.

Anencephaly

– Absence of major brain parts due to neural tube closure failure.

Spina Bifida

– Incomplete spinal cord closure during development.

Phenylketonuria (PKU)

– Genetic disorder causing toxic phenylalanine buildup.

Fetal Alcohol Spectrum Disorder (FASD)

– Cognitive and structural deficits from prenatal alcohol exposure.

Teratogen

– Substance causing developmental defects (e.g., alcohol, drugs, toxins).