MCB 150: Exam 3

1. Cargo protein presents NES signal 2. Ran-GTP binds to exportin, causing the cargo protein to also bind to exportin 3. Entire complex crosses NPC into cytoplasm 4. GAP hydrolyzes Ran-GTP to Ran-GDP which releases exportin, causing the cargo protein to also separate 5. Exportin and Ran-GDP go back to the nuclease 6. GEF removes the GDP and replaces it with GTP making Ran-GTP

o 16.5kb in human o 13 protein coding genes o Can form special mitochondrial ribosomes § 2 rRNA genes (1 per subunit) · 12S: small subunit · 16S: large subunit o 22 tRNA o ori in D-loop (stretch of gene-less DNA)

1. Chaperone proteins keep cargo protein with transit sequence from folding (for ease of transport through pore (translocon)) 2. Receptor protein of the TOM (Translocon of Outer Membrane) recognizes transit sequence 3. TOM and TIM are brought closer together and open up 4. As protein goes through (due to electrochemical attraction of positive transit sequence to negative matrix, therefore does not require ATP), transit sequence first, chaperone molecules are peeled off in the cytoplasm by hydrolyzing ATP 5. Once in the matrix, the transit sequence is cleaved off by Transit peptidase (AKA Mitochondrial Processing Peptidase [MPP]) 6. TIM has special chaperone proteins that help pull protein through 7. New chaperone proteins help cargo protein to fold and then are peeled off in an ATP dependent manner 8. Chaperonin Complexes can also take in the cargo protein and aid in its folding

- DNA Polymerase is wrong 1 in 100,00bp - DNA Polymerase III can act as an 3'-5' exonuclease and is done by it's epsilon unit

1) MutS scans for incorrect base 2) MutH binds to Adenine of 5'-GATC-3' and cuts the non-methylated strand 3) DNA Polymerase III and Ligase replace the bases *MutL holds MutS and MutH together

Fixes dimers or "kinks" caused by UV radiation which create covalent bonds between pyrimadines of the same strand

Sensitivity to UV light due to inability to repair UV damage on DNA

- 45S gene arrays (will be processed into 5.8S, 18S, and 28S segments that make up rRNA) - Found on human chromosome 13-15, 21, and 22 - Chromosome 1 has 5S arrays - Nucleolus forms around the 45S arrays, forming Nuclear Organizing Regions, or NOR

- Formation that exists during transcription of rRNA genes. - Very active and efficiently initiated when needed - Looks like sideways Christmas trees threaded along a string - “Ornaments” are Ribosomal subunits and sNoRPs

- Fibrillar region o Lighter region inside circular dense fibrilar region o DNA - Dense fibrilar region o Exists as dark rings o All work is done here; sNoRPs Ribosomal proteins - Granular region o Looks like sand o Pre-ribosomal particles

o Transition- Mutation where purine switches with another purine/pyrimidine switches with another pyrimidine o Transversion- Purine switches with pyrimidine, vice-versa

Defective Beta-globin subunit of red blood cell which changes the charge of the protein unit, making oxygen transport difficult - Due to single-base pair substitution - 1 in 600 blacks have it - 1 in 12 are carries `

- Newborns are screened for it and can be avoided with proper diet - Caused by an amino acid change in a 451 amino acid enzyme - Neurotoxic phenylalanine levels build inhibiting thyroxine and melanine

Nonsense mutation

- Faulty CFTR protein - In frame deletion of Phe at 508 of 1400 - Cl- cannot pass into mucus, causing mucus to dry, and creating an osmotic imbalance

o Insertion o Duplication o Inversion § Genes switch order on chromosome o Translocation § Genes from sister chromatids switch between chromatids § “Crossing-over”

Caused by translocations

Duplication

Duplication of short repeated sequences

Duplication of short, repeated sequences

Can be caused by inversions

- Loss of clotting factor VIII - Caused by insertions

Deletion

o S sequence is folded and threaded into the nuclear pore complex (N-terminus first) o Signal sequence is cleaved off