Genes

The functional element of chromosomes containing genetic information.

Defined as a unit base sequence that encodes a specific polypeptide sequence.

Stored information is primarily in a linear DNA sequence utilizing 4 amino acids.

There are approximately 30-40,000 genes in the human haploid genome.

The location on a chromosome defines the likelihood that a portion of one chromosome will interchange with the corresponding portion of its complementary chromosome when genetic recombination occurs during meiosis.

A typical gene contains coding sequences, exons, that are interrupted by stretches of noncoding sequences, introns.

Principal regulation in gene expression occurs at the level of gene transcription where information contained in genomic DNA into mRNA by specific DNA dependent RNA polymerase.

Gene regulation related to interactions of DNA with regulatory proteins and RNA molecules.

Many genes are marginally regulated, if at all, and yield proteins that are essential for normal cell function or survival and are maintained in a steady-state under all circumstances.


Many genes are not expressed or modestly expressed under basal conditions but under situations of stress or when cells are exposed to an agonist cells the expression of the genes may be induced or enhanced.

Many genes are nested within other genes, and genes can occur on forward and reverse strands of the same DNA sequence.

A single gene can encode multiple proteins or RNA molecules.

The promoter region of the gene influences the rate and extent of transcription which begins at the transcription start site.

Defines cell forms and function from transcription of genes, followed by translation and post-translational regulation.

Regulated at multiple levels including transcriptional, posttranscriptional, translational and posttranslational.

Responsible for more than 5000 rare Mendelian diseases.

More than 100,000 associations between genomic regions and common diseases have been discovered.

Due to the damaging effects that mutations can have on genes, there are  mechanisms such as DNA repair to prevent or correct mutations by reverting the mutated sequence back to its original state.


Mutations can involve the duplication of sections of DNA, usually through genetic recombination.


DNA duplications are a major source of raw material for evolving new genes.


Most genes belong to larger gene families of shared ancestry, detectable by their sequence homology.


Gene-specific transcription is one of the primary gene regulatory steps in the cell and relates to the cell type and state of differentiation as well as to external stimuli.

Methylation is a mechanism that silences specific genes in the genome.

In each cell only about 15% of the genome is active.

Any two people share 99.9% of DNA sequences, indicating the diversity is encoded in 0.1% of DNA.

0.1% of DNA sequences represents about 3 million base pairs.

Every gene has some level of polymorphism.

The single nucleotide polymorphism is the most common form of DNA variation in the human genome and typically are biallelic, and they may occur anywhere in the genome within exons, introns, or intergenic regions.

Related to age related macular degeneration, myocardial infarction, and abnormal cardiac repolarization.

Four loci associated with type 2 diabetes: incluning gene TCF7L2 and SLC30A8, the latter expressed in insulin producing beta cells.


Novel genes are produced by several methods, commonly through the duplication and mutation of an ancestral gene, or by recombining parts of different genes to form new combinations with new functions.


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