Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
|
Homology dependent mechaisms- nucleotide excision repair
|
Glabal genemic repair, bla bla
|
|
|
Glabal genemic repair
|
RAC, SBC
|
|
|
DNA mismatch repair
|
GATC: whenever this sequence is present, T got methylated
|
|
|
Muts, MutA
|
base pair mismatches recognized by scaning after replications and newly synthesized strand is repaired
New strand recognzed due t time lag of DNA methylation and other modification |
|
|
Error-prone mechanisms- SOS/translesion repair
|
bulky additions &/or pyrimidine dimers can lead to stalling of DNA polyerase & cell death
|
|
|
In order to let replication continue, an error-prone DNA repair system is activated that
|
puts random nucleotides opposite the lesion
|
|
|
ACtivation of bypass polyerases
|
Large active site pocket, can accommodate DNA adducts
No 3-5 proofreading activity- allowed to make mistakes Only add a few nucleotides |
|
|
DNA repair mechanisms, double-stranded break repair
|
they are problematice since can lead to chromosomal rearrangement'
cab lead to nonhomologous end-joining ( ends are trimmed and ligated back together) this lead to deletion, erorr -prone) |
|
|
Homologous double strand break repair
|
Synthesis-dependent strand annealing: in cells that have already replicated DNA
- End-trimming o double stranded breaks Rad51 binds single-stranded ends and Rad51-DNA filament mediates search for sister chromaid & strand invasion.Syster chromatid used as template to synthesize missing DNA Ligase seals nicks |
|
|
Mutation and diesease
|
Diseases can be caused by
1. Mutation sthta alter functiona l products of specific key genes (eg sickle cell, CFTR) 2, Accumulation of nuerous mutations in genes with related function ( cancer) 3. Mutation of repar enzyme genes (xeroderma pign=nent stotum |
|
|
LEcture 27
|
The transposable element
|
|
|
Unstable alleles in maize
|
cross C/Cx c/c parents sometimes get varietigation.
|
|
|
Hybrid dysgenesis in fruit flies
|
female stock x wild male = sterile
|
|
|
Variegation was associated with a specific chromosomal break that led to loss of the regional function
|
disociator
Genetics & the detection of the unexpected: Wild type kernal with a section of mutant |
|
|
Isolated rare unstable c (mutant) alleles caused by Ds
|
Affected only the C gene, mosaic kernales whee c reverted t wild type
|
|
|
WHat do trabsposavle elenbe kiij like
|
Many different tupes
DNA transporsons (pre & eukaryotes) CLass II element Retrosposon element |
|
|
General structure of DNA transposons
|
encoded transposase, terminal inverted sequence .
|
|
|
HOw do DNA TEs jump
|
Convervative: cut and paste into new location
Most common mechaism |
|
|
Conservative transposition of DNA TEs
|
transposase-mediated
cut at target site |
|
|
General feature of transposon
|
Eukaryote elements that junp through ab RNA intermediated, they usually have long termial repeat and ther is no transposase. Transposition requires retrotransposon-encoded reverse transcriptase (pol )
|
|
|
Transposition of LTR retrotransposons
|
replicative mechamos,
RNA or LTR retrotransposon is reverse transcribed to DNA in cytoplasm then DNA copy returned to the necleus for inseertion into the genome Viruses make many RNA copies that are packaged for dispersal. |
