Module 5 Flashcards
Study of mechanisms that change gene expression by modifying the DNA without modifying its base sequence
Study of the changes in the regulation of gene activity and expression that are not dependent on gene sequence
Refers to both heritable changes in gene activity and expression in progeny cells or individuals
Epigenetics
Mechanisms in Epigenetics
1) DNA methylation
2) Histone modification
Mechanism wherein A methyl group is added to the 5’ carbon position of cystosine residues in DNA; Facilitated by methyl transferase
DNA Methylation
Methylation ________ in the DNA sequence, but it does not interfere with the Watson-Crick pairing of DNA—the methyl group is positioned in the _______ of the DNA
adds information not encoded; major groove
As an example in cancer, this is the result of ________ which reverses the inactivation of certain genes, and leads to unrestricted transcription of many gene sets such as oncogenes
Hypomethylation
As an example in cancer, this is the result of ________ that silences other genes such as tumor-suppressing genes
hypermethylation
Changes in the chromatin structure when histone proteins are chemically modified by adding or subtracting a methyl or acetyl group
Histone Modification
How does methylation and acetylation of histones affect the DNA and consequently its genes?
Methylation: Tightens up DNA restricting access to genes
Acetylation: Unravels DNA making genes more available for activation
Enzymes involved in Histone Modification
HATs–histone acetyl transferases
DNMTs–DNA methyl transferases
MBPs–methyl-CpG binding proteins
HDACs–histone deacetylases
Study of how food affect our genes and how genetic differences can affect the way we respond to nutrients and other naturally occurring compounds in the food we eat
Studies molecular relationships between nutrition and response of genes
Nutrigenomics
5 Tenets of Nutrigenomics
1) Diet can be a serious risk factor for a number of diseases
2) Gene expression and structure can be altered directly or indirectly by the chemicals in the diet
3) Degree diet influences balance between healthy and diseased states depend on genetic makeup of an individual
4) Diet-regulated genes may play a role in the onset, incidence, progression and/or severity of chronic diseases
5) Dietary interventions can be used to prevent, mitigate or cure chronic diseases
What is the endosymbiotic hypothesis and what are the evidences presented for it?
Chloroplasts and mitochondria were once prokaryotes that entered eukaryotic cells.
Evidence: They have their own genes and can replicate themselves
Most abundant and most important protein on earth
Catalyzes first step in carbon fixation during the Calvin cycle of
photosynthesis
Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO)
