Exam 1 Lecture Notes
- University of Wisconsin - Madison
- Zoology 570
- Exam 1 Lecture Notes
Last Modified: 2011-09-27
Related Textbooks:Molecular Cell Biology (Lodish, Molecular Cell Biology)
- attachment of fluoropheres can compromise protein function
- not easy to purify proteins, esp. when needed in entirety
- limited life span of protein in cell, degrades
- microinjection is slow and difficult; limits number of cells in experiments
helical polymers made up of a protein called actin, ~4nm in diameter, concentrated in cell cortex, the region just inside the membrane. Active jobs include promotion of "cell crawling", cytokinesis, and maintaining cell shape
hollow tubes, ~25nm in diameter, made up of protein called tubulin; extend from a focus point outside nucleus to place on cell periphery
fibrous structures, ~10nm in diameter,made up of numerous proteins called intermediate filament proteins, such as laminas, keratins and vimentin; underlay and wrap around outside nuclear envelope & extend out to plasma membrane
the strand of template DNA on which DNA synthesis is continuous because the DNA polymerase can keep synthesizing as long as MCM separates DNA
DNA is discontinuous because new DNA PA has to keep landing as MCM complex separates DNA
- Helicase unwinds/"unzips" DNA by breaking the H-bonds
- RNA nt paired with cmplmtry DNA bases.
- RNA sugar-phosphate backbone forms w/ help from RNA pol.
- H-bonds of the untwisted RNA+DNA helix break, freeing the newly synthesized RNA strand.
- RNA further processed (addition of a 3' poly-A tail and a 5' cap), exits thru to cytoplasm via nuclear pore
- the promoter is ~50-200bp and have a region called the core promoter (runs from ~-1 to ~-50nt from gene)
- has a TATA box @ about -25nt from gene
- usually 7-9nt from gene, transcriptional machinery will begin to assemble
TFII A,B, & F
binds to polymerase II, binds to TFIIH
binds to polymerase II and DNA, TFIIE, has helicase and kinase activity
specially modified nucleotide (7-methylguanosine) is attached to the 5' end of the transcript
- generated and added to transcript by the capping enzyme complex (CEC), which associates w/ pol II and as 5' end emerges, CEC caps it.
- necessary for export from nucleus and to
removal of introns from the transcript and linking of exons, loops introns which cuts them out and is eventually degraded
- Exons will be represented in final (mature) transcript
- much is done by "spliceosomes", structures made of protein and small nuclear RNA (catalytic part is RNA, not protein)
- some splicing, however, does not require spliceosomes but is done by the transcript itself (self-splicing)
provides cell ability to generate multiple mRNA's and thus multiple proteins from a single gene
3' end processing
immature transcript is cleaved to generate 3' end and then usually polyadenylated (long runs [10-200] of A's are added
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