Molecular Biology: Genes and Expression Lecture 11

This collection of flashcards covers key concepts in molecular biology related to gene expression, mutations, and the genetic code.

X chromosome inactivation

The process in which one of the two X chromosomes in females is randomly inactivated.

Barr body

The inactivated X chromosome that is transcriptionally inactive.

Dosage compensation

A process that balances expression of sex-linked and autosomal genes in the heterogametic sex.

One-gene, one-enzyme hypothesis

The hypothesis proposing that each gene encodes one enzyme.

Codon

A group of three nucleotide bases that specifies a particular amino acid.

Triplet code

A coding system where sequences of three nucleotide bases correspond to amino acids.

Point mutation

A permanent change in a single base pair of DNA.

Missense mutation

A mutation that results in a different amino acid being incorporated into a protein.

Nonsense mutation

A mutation that changes an amino acid codon into a stop codon.

Silent mutation

A mutation that does not change the amino acid sequence due to redundancy in the genetic code.

Frameshift mutation

A mutation that alters the reading frame of the genetic sequence, affecting all subsequent codons.

Genotype

The genetic constitution of an organism as determined by its DNA sequence.

Phenotype

The observable physical or biochemical characteristics of an organism as determined by both genetic makeup and environmental influences.

Central dogma of molecular biology

The flow of genetic information from DNA to RNA to proteins.

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process of synthesizing proteins from mRNA templates.

Xic region

The X chromosome inactivation center, responsible for inactivating one of the X chromosomes in females.

Xist

The X inactivation specific transcript that coats the inactivated chromosome.

Null allele

Nonfunctioning alleles that do not produce a functional protein.

Genetic code

The set of rules by which information encoded in genetic material is translated into proteins.