W3, Neurogenetics and Introductory Genetics

This set of vocabulary flashcards covers introductory genetics concepts, Mendelian inheritance, chromosomal abnormalities, X-linked conditions, epigenetics, and the use of animal models in neurogenetics research.

Genetics

The scientific study of inherited variation, focusing on how traits are passed down through generations and the role of genes in determining those traits.

Chromosome

A tightly wound coil of DNA found inside cells; humans possess $23$ pairs of chromosomes.

Deoxyribonucleic acid (DNA)

The molecular structure of nucleic acids made of a nitrogen-containing base, a five-carbon sugar, and a phosphate group, forming a double helix.

Complementary Bases

Nitrogenous base pairs held together by hydrogen bonds, specifically Adenine-Thymine ($A-T$) and Cytosine-Guanine ($C-G$).

Transcription

The process where a transcription factor binds to DNA to attract RNA polymerase, which uses DNA as a template to produce messenger RNA (mRNA).

Translation

The process where a ribosome attaches to mRNA and reads triplet codons ($3$ bases) using transfer RNAs (tRNA) to link amino acids into a protein.

Single Nucleotide Polymorphisms (SNPs)

Natural variations in the DNA sequence where a single base differs; they occur approximately in $1$ in every $1000$ bases.

Mitosis

A type of cell division occurring in somatic cells where the daughter cells are genetically identical to the parent cell.

Meiosis

A type of cell division occurring in gametes where daughter cells contain half the number of chromosomes ($1/2$).

Law of Segregation

Mendel's law stating that each individual has two alleles of a gene that separate during meiosis so each gamete receives only one.

Law of Independent Assortment

Mendel's law stating that genes for different traits are inherited independently of each other unless they are linked on the same chromosome.

Genotype

The specific genetic information or makeup of an individual.

Phenotype

The observable physical traits of an organism, resulting from the interaction of the genotype with the environment.

Huntington's Disease (HD)

An autosomal dominant disorder caused by an excessive repeat of CAG bases (over $40$ copies) in the HTT gene on Chromosome $4$, leading to neuron death in the striatum.

Autosomal Dominant Inheritance

A pattern of inheritance where a single copy of a mutant allele is sufficient to cause the disease, resulting in a $50\%$ chance of offspring inheritance if one parent is affected.

Phenylketonuria (PKU)

An autosomal recessive disorder caused by a mutation in the PAH gene, leading to a lack of the enzyme that breaks down phenylalanine.

Trisomy

A chromosomal abnormality involving three copies of a chromosome instead of two, such as Downs syndrome (Trisomy $21$).

X-inactivation

A developmental process in females where one of the two X chromosomes is randomly silenced and condensed into a Barr body to maintain gene dosage.

Rett Syndrome

An X-linked progressive neurodevelopmental disorder caused by a mutation in the MeCP2 gene, which acts as a transcriptional repressor.

Fragile X Syndrome

The most common inherited form of learning disability, caused by a CGG repeat expansion ($200+$ copies) in the $5'$ UTR of the FMR1 gene.

Epigenetics

The study of modifications to DNA, such as methylation, that regulate gene expression (turning genes on or off) without changing the actual DNA sequence.

Genome Wide Association Studies (GWAS)

Large-scale studies that look for which SNPs across the entire genome sort with specific disease states, such as Alzheimer's or schizophrenia.

Concordance

A term used in twin studies to describe the degree to which a trait is seen in two individuals.

Knockout Mice

Genetically engineered mice where a specific gene has been removed or inactivated to study its biological function.

Synteny

The shared order of genes on chromosomes between different species, such as the intact presence of the Down Syndrome Critical Region from human Chromosome $21$ on mouse Chromosome $16$.