The Dogma - answer-- the step-by-step process from DNA to mRNA to proteins
- What is encoded as DNA ends up as proteins
Regulation of Proteins: - answer-- transcription
- translation
- posttranslational modifications
Organization of Genetic Information - answer-- DNA sequences are organize...
Organization of Genetic Information - answer-- DNA sequences are organized in genes the
contain information to code for proteins
- genes are located on chromosomes and tightly packed in a structure of DNA and protein
(histones)
Regulated Transcription - answer-- the means by which a cell regulates the conversion of DNA
to mDNA and orchestrating gene activity
History of DNA - answer-- biologists discovered that genetic instructions are carried on
chromosomes
- chemists discovered that chromosomes are made up of proteins and DNA
- DNA was the component that carries genetic information
Discovery of DNA - answer-- Rosalind Franklin used x-ray diffraction to look at DNA but could
not decipher it
- Watson and Crick used Franklins photo to correct their model of the DNA helix and made the
discovery
- the three all contributed to the discovery
DNA Structure - answer-- base pairs on the inside
- A/T's and G/C's
- hydrogen and oxygen on the sugar backbone
Major Features of DNA - answer-1) DNA is a double-stranded helix (with A/T's, G/C's)
connected by hydrogen bonds
2) DNA helices are right handed
3) DNA double helix is anti-parallel (5' end paired with 3' end)
4) DNA base pairs are connected by hydrogen bonding and nitrogen bases
Estrogen and DNA - answer-- has neuroprotective effects
- a hormone that passes through the membrane and binds to its receptor (E2)
- when E2 is bound to the ER, it forms a complex that can bind to DNA in the nucleus
Transcription - answer-- promoter section located upstream of target gene (recognition sire)
- activation of gene expression is induced by the sequential recruitment of large multi-subunit
protein co-activator complexes through binding
Example of Transcription (estrogen) - answer-- the complex binds to the recognition site/DNA
motif
- the chromatin opens up enough to allow TF's to bind to the motif
, - TF's bring in co-activators and initiate nucleosome remodelling
- General Transcription Factors allow RNA Polymerase II to transcribe
Epigenetic Regulation - answer-- factors can result in methylation (ex. stress) that reduce gene
expression
- Brain Derived Neurotrophic Factor (BDNF) can be modified by chromatin remodelling
- antidepressants reverse the suppression of BDNF by increasing histone acetylation
Epigenetics - answer-- the study of changes in organisms caused by modification of gene
expression rather than alteration of the genetic code itself
Chromatin - answer-- the material that makes up the chromosomes
- wound and unwound protein-chromosome complexes
- 1 chromatin contains approx. 146 base pairs
Histone Acetyltransferase (HAT) - answer-- enzymes that acetylate conserved lysine amino
acids on histone proteins by transferring an acetyl group
- loosely packed chromatin
Histone Methyltransferase (HMT) - answer-- enzymes that catalyze the transfer one or more
methyl groups
- tightly packed chromatin
Chromatin Remodelling - answer-- begins with the presence of HAT's and lack of HMT's
- addition of SWI/SNF complex that opens up DNA
Nucleosome - answer-- simplest packaging structure of DNA found in all eukaryotic
chromosomes
- DNA is wrapped around the octamer of small basic proteins called histones
- this contains 8 subunits/histones in each structure
Histone Acetylation - answer-- modification occurs at lysine amino acids (involves the addition
and removal of acetyl groups)
- the level of acetylation f the histones determines how tightly the DNA is would around the
histones and how tightly the nucleosomes are stacked together
Hyperacetylation - answer-- chromatin is relaxed and accessible to the transcription proteins
- results in increased gene transcription
Hypoacetylation - answer-- chromatin is condensed, preventing access of transcription proteins
- results in decreased gene transcription
Histone Deacetylases (HDAC) - answer-- a class of enzymes that remove acetyl groups from
lysine amino acids allowing histones to wrap DNA more tightly
- enzymes that can remove acetyl groups from histone proteins
- can be effective to treat for cancer cells
DNA Methylation - answer-- chromatin structure can be modified by adding methyl groups to
certain DNA segments
- methylation can inhibit transcription directly or indirectly
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