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;
37 Cards in this Set
- Front
- Back
- 3rd side (hint)
Helicase
|
Unwinds DNA at replication fork
|
|
|
Single-stranded binding proteins
|
prevents strands from reannealing
|
|
|
DNA topoisomerase
|
nicks helix to relieve supercoils during replication
|
Fluoroquinolones - inhibit DNA gyrase (prikaryotic topoiomerase II)
|
|
Primase
|
Makes RNA primer on which DNA polymerase III can initiate replication
|
|
|
DNA polymerase III
|
Prokaryotic ONLY. Elongates strand by adding nucleotides to the 3' end. Elongates lagging strand until it reaches primer of the preceding fragment. 3'-5' exonuclease proofreads added nucleotides
|
5'-3' synthesis and proofreads with 3'-5' exonuclease
|
|
DNA polymerase I
|
Prokaryotic ONLY. Degrades RNA primer and replaces with DNA
|
Same function as DNY polymerase III but also excises RNA primer with 5'-3' exonuclease.
|
|
DNA ligase
|
Catalyzes phosphodiester bond within a strand of double-stranded DNA. Joins Okazaki fragments
|
|
|
Telomerase
|
Adds DNA to 3' end of chromosomes to avoid loss with each successive duplication
|
|
|
Nucleotide excision repair
|
Repairs helix-distorting lesions (ie pyramidine dimer from UV light exposure). Endonucleases release the damaged bases, DNA polymerase and ligase fill and reseal the gap.
|
Mutated in Xeroderma Pigmentosum
|
|
Base excision repair
|
Glycosylases recognize and remove damaged bases (ie spontanious/ toxic deamination) apurinic/apyramidinic endonuclease cuts DNA, empty sugar is removed, gap is filled/resealed
|
|
|
Mismatch repair
|
Newly synthesized strand is recognized, mismatch nucleotides are removed, gap is filled and resealed.
|
Mutated in Hereditary nonpolyposis colorectal cancer (HNPCC)
|
|
Non-homologous end joining
|
Brings together 2 ends of DNA fragments to repair double-stranded breaks. Homology not required.
|
Mutated in ataxia telangiectasia
|
|
rRNA
|
ribosomal RNA
|
most abundant (r=Rampant)
|
|
mRNA
|
messenger RNA
|
longest (m=Massive)
|
|
tRNA
|
transfer RNA
|
smallest (t=Tiny)
|
|
mRNA start codons
|
AUG (GUG)
|
eukaryotes: methionine. removed before translation is complete
prokaryotes: formylmethionine (f-met) |
|
mRNA stop codons
|
UGA
UAA UAG |
UGA = U Go Away
UAA = U Are Away UAG = U Are Gone |
|
Promoter
|
RNA polymerase and other transcription factors bind to DNA upstream from gene locus (AT-rich upstream sequence with TATA and CAAT boxes)
|
mutation results in dramatic decrease in gene transcription
|
|
Enhancer
|
Stretch of DNA that alters gene expression by binding transcription factors
|
May be located close to, far from, or within (intron) the genes they regulate
|
|
Silencer
|
Site where negative regulators (repressors) bind
|
May be located close to, far from, or within (intron) the genes they regulate
|
|
RNA polymerase I (eukaryote)
|
makes rRNA
|
|
|
RNA polymerase II (eukaryote)
|
Makes mRNA. Opens DNA at promotor site.
|
α-amanitin (in Amanita phalloides) inhibits - causes hepatotoxicity.
|
|
RNA polymerase (prokaryote)
|
multisubunit complex makes all 3 types of RNA
|
|
|
RNA processing (eukaryote)
|
hnRNA (if it's to be translated = pre-mRNA)
- 5' cap (7-methylguanosine) - polyadenylation of 3' (200 As) by Poly-A polymerase which does not require a template (AAUAAAA = signal) -Splicing out of introns |
|
|
pre-mRNA splicing
|
-snRNPs and proteins make spliceosome
-Lariat intermediate -Lariat released, exons joined |
Antibodies to step 1 formed in lupus
|
|
tRNA
|
75-90 nucleotides, 2º structure, cloverleaf shape. CCA at 3' end with chemically modified bases. Amino acid covelently bound to 3' end
|
|
|
Charging tRNA
|
Aminoacyl-tRNA synthetase (1 per amino acid, uses ATP) adds correct amino acid (removes incorrect)
|
Tetracyclines inhibit
|
|
Silent point mutation
|
same amino acid (usually a change in 3rd position of codon)
|
|
|
Missense point mutation
|
changed amino acid (conservative - new amino acid is similar in structure)
|
|
|
Nonsense point mutation
|
Change results in early stop codon
|
|
|
Frameshift mutation
|
Change results in misreading ALL nucleotides downstream - usually a truncated or nonfunctional protein
|
|
|
tRNA wobble
|
accurate base pairing is only required for the first 2 nucleotide positions, so different 3rd positions can code for the same tRNA/amino acid
|
|
|
Protein synthesis - Initiation
|
activated by GTP hydrolysis, initiaion factors assemble subunits with initiator tRNA, released when complex assembles
Eukaryotes: 40S + 60S => 80S proaryotes: 30S + 50S => 70S |
Aminoglycosides
|
|
Protein synthesis - Elongation
|
1) Aminoacyl-tRNA binds to A site
2) Ribosomal rRNA ("ribozyme") catalyzes peptide bond, transfers to A site 3) Ribosome advances 3 nucleotides (toward 3' end) A site = incoming Aminoacyl-tRNA P site = accomodating growing Peptide E site = holds Empty tRNA as it Exits => APE |
Tetracyclines inhibit 1)
Chloramphenicol inhibits 2) Macrolides inhibit 3) |
|
Posttranslational modification: Trimming
|
Removal of N' or C' propeptides from zymogens
|
|
|
Posttranslational modification: Covalent alteration
|
Phosphorylation, glycosylation, hydroxylation, methylation, and acetylation.
|
|
|
Posttranslational modification: Proteasomal degradation
|
Attachment of ubiquitin to defective proteins to tag them for breakdown.
|
|