Functions & Dysfunctions of Genetic Regulation Flashcards
Central Dogma of Genetics
DNA–> RNA–>protein (via transcription, translation)
Structure of DNA
double helix, sugar/phosphate backbone w bases (AGCT); antiparallel strands
Euchromatin
protein involved w DNA Packaging, ubiquitous within DNA, almost always activated
Heterochromatin
condensed DNA, found mainly in centromeres and at the edges, very little gene expression
methylation on packaging
adding a methyl group
base pairing
A and T have 2 double bonds, G and C have 3 (stronger); 142 h-bonds b/w DNA and histone octamer
DNA packaging
DNA wraps around a histone w condensed chromosomes that prevent mutations and protect against damage
Structure of histone
Proteins made up of a lot of AA but specifically many Lysine and Arginine (basic, positively charged) that attract the negatively (from phosphate groups) charged DNA
Mnemonic: Lysine Arginine Histone
Human genome project
Began in late 90’s early 2000’s and took a very long time to finish and it was only 90% done; cost a billion dollars whereas now it takes about 24 hours and $1000
Personalized medicine
Uses each patient’s individual DNA to hybridize information
Binding proteins to DNA
1) Histones
2) non-histone binding
Nucleosomes
Basic unit of chromosome packing (includes histone and non-histone portion); 8 histone proteins (histone octamer)
Chromatin
Protein + DNA
Position effect
Gene activity is based on location on the chromosome
If a previously actively expressed gene is moved near the heterochromatin (centromere or telomere)—> becomes silenced
Alternative RNA splicing
Exons/introns can be cut differently on the RNA to produce different gene combos (avg: 2 different ways/ genes)
Histone Deacetylation (HDAC)
HDAC activity represses gene activity by removing acetyl group and resestablishing normal DNA-histone interaction
Histone Acetyl Transferase (HAT)
Add an acetyl group to histone (N-terminal lysine) which reduces DNA interaction because the positive charge is removed;promotes gene expression as its not as tightly wound
Ex: estrogen (steroid hormone) promotes gene expression
DNA Methylation
Adding methyl group to DNA (cytosine and adenine) by specific methyl transferase enzymes
Change activity but not DNA sequence (ex: will repress gene expression when its at a gene promoter)
Key processes affected: genomic imprinting, xchromosome inactivation, repression of transposable elements, aging, carcinogenesis
Hypermethylation
**important in Cancer Development
Gene promotes will lead to silencing/target
Hypomethylation
Too little methylation—> inactivate chromosome and loss of imprinting abilities
DNA Replication
DNA polymerase (DNA-dependent) synthesizes new DNA from 5’-3’; NEEDS free 3’ OH
New chain is assembled based on the template of the old chain (needs to be separated and then double are made)
Requires dATP, dGTP, dCTP, dTTP
Replication fork
Origin & direction of expansion
Semi-discontinuous
HAS to go from 5’—3’ but not both sides can be the correct way sooo one side is leading and one is lagging
Lagging strand goes from 3’-5’ of ORIGINAl but is made 5’-3’ in Okazaki fragments