Chapter 18: Gene Regulation
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What are the three types of gene regulation?
Pre-transcriptional, post-transcriptional, post-translational
What is the purpose of pre-transcriptional gene regulation?
to modify DNA to inhibit or speed up transcription, possible through the use of operons
What is an operon?
Related genes are often found in a cluster on the chromosome, where they are transcribed from one promoter (RNA polymerase binding site) as a single unit. Such a cluster of genes under control of a single promoter is known as an operon. Can be switched on or off.
What is an inducible operon?
An operon which is normally off but can be switched on.
What is a repressible operon?
An operon which is normally off but can be switched on.
What is DNA methylation?
“Silencing gene”, a CH3 group binds to DNA and inhibits transcription.
What is histone acetylation?
Adding acetyl group (CH3CO) to histone; opened and unwound segments called heterochromatin are always able to be transcribed Alters accessibility of chromatin
What is the purpose of post-transcriptional gene regulation?
To control gene expression at RNA level by regulating finished mRNA strand
What is alternative mRNA splicing?
Removing introns and the differential arrangement of exons to create related but different mRNA strands (i.e., ABC, ACB, BAC…)
What is siRNA?
Small-interfering RNA: complementary to given strand of RNA, forms H bonds, prevents translations Prevents translation by blocking RNA bonds
What is miRNA?
Micro-RNA: binds and tags RNA for destruction
What is the purpose of post-translational gene regulation?
It regulates and ensures success of the last step of gene expression, i.e., the rate of protein turnover.
What are proteosomes?
Proteins that modify or destroy proteins depending on chemical tagging.
What do a protein + lipid make?
Cholesterol
What do a protein + sugar make?
Glycoprotein
What do a protein + protein make?
Protoprotein
What is epigenetics?
Environmental impacts on gene expression which DO NOT change DNA nucleotides
What percentage of DNA is protein-coding?
1%
What is a cytoplasmic determinant?
Molecules made by cells that signal new cells how to form or what to become
What are HOX genes?
Genes that determine positional and pattern info (axis and segmentation) for the body.
What are the other names of HOX genes?
Homebox, homeotic
What are proto oncogenes?
“Gas pedal” for cell division, necessary for cell/organism growth
What are tumor suppressor genes?
“Brakes” for cell division, causes cell termination and prevents overgrowth of cells.