Genetics Review: Molecular Basis and Single Gene Diseases

A set of vocabulary flashcards covering the molecular basis of genetics, genome composition, mutation types, and Mendelian/non-Mendelian inheritance patterns based on lecture notes.

Gene

The structural and functional unit of genetic material that encodes proteins or RNA, including regulatory sequences that ensure transcription, translation, and expression.

Pangenesis → Factor → Gene

The historical evolution of the concept of the gene as defined in the notes.

Nuclear Genome

A genome composed of $3.2 \times 10^9$ bp containing approximately $2 \times 10^4$ to $2.5 \times 10^4$ genes.

Mitochondrial Genome

A genome consisting of $16.6\,kb$ containing $37$ genes.

DNA Composition Ratio

The distribution in the genome where coding regions account for approximately $10\%$ and non-coding regions account for approximately $90\%$.

Levels of Gene Regulation

The five levels of control: pre-transcriptional, transcriptional, post-transcriptional, translational, and post-translational regulation.

Synonymous Mutation

A type of point mutation where the encoded amino acid remains unchanged.

Missense Mutation

A type of point mutation that results in the replacement of one amino acid with another.

Nonsense Mutation

A type of point mutation that causes premature termination of the protein chain.

Frameshift Mutation

An insertion or deletion that leads to a change in the reading frame.

Dynamic Mutation

Trinucleotide repeat expansion, a process seen in conditions such as Huntington's disease.

Autosomal Dominant (AD) Inheritance

A pattern where the mutation is on chromosomes $1$ to $22$ and heterozygotes ($Aa$) manifest the disease; it is characterized by equal risk for males and females and continuous transmission.

Autosomal Recessive (AR) Inheritance

A pattern where only the $aa$ homozygote manifests the disease, and carriers ($Aa$) are asymptomatic; it often features non-continuous transmission and increased risk in consanguineous marriages.

X-linked Dominant (XD) Inheritance

A pattern where female heterozygotes manifest the disease, males are often more severely affected or rare, and females are affected more frequently than males.

X-linked Recessive (XR) Inheritance

A pattern where male hemizygotes or female homozygotes manifest the disease, characterized by more male patients and non-continuous transmission.

Y-linked Inheritance

A pattern where only males are affected and the trait is passed from father to all sons (e.g., hairy ears).

Pleiotropy

A phenomenon where a single gene affects multiple phenotypic traits, such as in Marfan syndrome.

Genetic Anticipation

A phenomenon often associated with dynamic mutations (like Huntington's disease) where the age of onset becomes earlier or severity increases in successive generations.

Genomic Imprinting

An epigenetic process where the expression of a gene depends on which parent it was inherited from, exemplified by Prader-Willi and Angelman syndromes.

Phenocopy

An environmentally induced phenotype that mimics a genetically determined trait.