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How many genes are in human DNA
20,000
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how many base pairs are in DNA
3.5 bil
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how many chromosomes in the human DNA
26 chromosomes
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width of a DNA strand
2 nm
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space between each base
0.34 nm
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how long is all the DNA in the cell
1 meter
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how many cells in the body
10-100 trillion
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how large is a eukary nucleus
10-20 microns
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how large is a eukary cell
50-400 microns
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how long is a chromosome
1- microns
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Chromatin
- material that contains DNA
- mixture of DNA and protein
- 50:50 mixture
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type of chromatin
- euchromatin
- heterochromatin
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euchromatin
- lightly packed DNA with lower density of genes
- light by EM
- ~10% genes
- ~1% coding genes
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heterochromatin
- non-coding repetitive elements, structural elements
- ~50% of genome is repetitive sequences
- dark by EM
- heavily packed
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projuria
caused by Lamin-A changes gene expression due to structural problem in the nucleus
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types of protein in chromatin
histones, DNA polymerase, and all regulatory machinery
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nucleosome
the 1st level of organization of a chromatin
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how many base pairs in a nucleosome
146
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structure of nucleosome
8 histones 4 different types of histones
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KASH
integral membrane protein that binds to the cytoskeleton and SUNS
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SUN
integral membrane protein that binds the lamens and KASH
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Lamens
intermediate filament
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what happens to lamens during mitosis
the lamen proteins are phsophorylated and break down
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what does histone H1 do
it makes the DNA with nucleosomes coil and coil until a solenoid is formed but that has not been completely proven
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RNA polymerase error rate
- 1/1000 bp, not that big of a deal
- mutation would be innocuous
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stemloop vs. hairpin
- hairpin-5-10 bp and loop
- stem loom - 100-700 bp and then a loop
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what direction does RNA polymerase read and what is the strand
3' to 5' end of the non-coding, template, antisense, transcribed strand
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what is the 5' to 3' strand named
coding strand, sense strand
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details about transcription
- only small fraction of genome is ever transcribed (~5%)
- happens during most of cell cycle (not M phase)
- Product is ssRNA
- no primer required
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types of RNA Poly
- Pol I - make ribosomal RNAs
- Pol II- make mRNA and microRNAs and some snRNAs
- Pol III - make tRNAs and snRNAs (regulatory RNAs)
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parts of a gene
promoter, UTR transcribed region UTR
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parts of the promoter
- UTR, transcribed region and another UTR
- core promotor w/ TATA box (-25 position)
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how long is the promotor
50-200 bp long
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percentage of exons and introns in gene
90% introns, 10% exons
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terminator sequence
polyadenylation sequence that forms a secondary structure which causes the RNA pol to slow/stop
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how fast does RNA pol work
30-50 bp/ second
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Transcription Initiation steps
- TF2 D binds TATA box- creates kink
- recruits TF2 A, B, F
- Pol II recruited
- TFII E, H recruited
- TFII H helicase activity and kinase
- phosphorylated pol II starts transcription
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Transcription Elongation steps
- 3' OH of last nucleotide forms phosphodiesterbond
- as RNA is processed, salts and proteins bind to new RNA
- RNApolII binds pretty tightly low k-
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Transcription termination
pol II slows/stops, triggers dissociation
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general structure of specific TF
DNA binding domain, +- regulatory domain (switch), and activation domain (bind activator proteins)
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activator proteins
- HATs - adds acetyl to positive lysine residues to weaken interaction of DNA and histone
- NRCs- remove histones from DNA
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HATs
- histone acteyl transeferases
- N terminal tail have lysine residues
- adds acetyl to lysine residue and removes + charge from histone
- weakens DNA association
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NRC
- nucleosome remodeling complex
- use ATP to move along DNA and remove histones
- when combined with HATs its more efficient
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corticosteroid
- lipid hormone
- excell signal that transfers into cytoplasm and binds to a regulation domain and is activated
- transported to the nucleus and effects transcription
- causes increase metabolism and hunger
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