Ch 18/14 Gene Expression / Mutations

Alter the physical structure of DNA, and can affect gene expression through reversible modifications of DNA or histones.

• Epigenetic changes

• Induction of transcription factors

• Observable cell differentiation

• Regulatory sequences

• Transcription factors

During development results in sequential gene expression

• DNA methylation

• Epigenetic changes

• Histone modification

• Induction of transcription factors

• Regulatory sequences

Results from the expression of genes for tissue-specific proteins.

• DNA methylation

• Epigenetic changes

• Histone modification

• Observable cell differentiation

• Regulatory sequences

Are stretches of DNA that interact with regulatory proteins to control transcription. They can promote or inhibit protein synthesis

• DNA methylation

• Epigenetic changes

• Histone modification

• Induction of transcription factors

• Regulatory sequences

One example of an epigenetic change, these proteins around which DNA is wound can bind to epigenetic factors. This in turn can alter the extent to which DNA is wrapped around and the availability of genes in the DNA to be activated.

• DNA methylation

• Histone modification

• Induction of transcription factors

• Observable cell differentiation

• Regulatory sequences

One example of an epigenetic change, the addition of a "chemical cap," to part of the DNA molecule, which prevents certain genes from being expressed.

• DNA methylation

• Histone modification

• Induction of transcription factors

• Observable cell differentiation

• Regulatory sequences

Are proteins that help turn specific genes "on" or "off" by binding to nearby DNA.

• Elongation

• Initiation

• Lac operon

• Termination

• Transcription factors

Pre-mRNA nucleotides are quickly paired with their complementary bases which correspond with the template strand of DNA. The pre-mRNA moves in the 5’ to 3’ direction while the template strand of DNA moves oppositely from the 3’ to 5’ direction.

• Elongation

• Initiation

• Lac operon

• Termination

• Transcription factors

When the RNA Polymerase reaches the terminator it signals the RNA Polymerase to stop and release from the DNA. Once separated the two DNA strands come back together and reform the double helix. The newly formed pre-mRNA molecule is then released.

• Elongation

• Initiation

• Lac operon

• Termination

• Transcription factors

In the nucleus, RNA polymerase recognizes the recognition sites causing it to bind to the promoter. The RNA Polymerase then separates the DNA into single strands so the template strand can be read in the 3’ to 5’ direction.

• Elongation

• Initiation

• Lac operon

• Termination

• Transcription factors