Flashcards in Younger Review Deck (69):
What does PRPP synthetase make?
Where does the ribose-5P come from?
HMP shunt, it then makes PRPP
What does PRPP amidotransferae make?
Takes PRPP and makes PRNH2 out of it
What is the regulated committed step in Purine synthesis?
What are the two enzymes of purine synthesis
PRPP synthetase and PRPP amidotransferase
What are the two possible fates of PRPP?
Go into purine synthesis or it can have a pyrimidine base added onto it
What is the regulated committed step for pyrimidine synthesis
What does CPS II do?
Starts making the pyrimidine base
What is a positive regulator for PRPP synthetase?
-folic acid analog
-an anti tumor drug that inhibits dihydrofolate reductase
-no DHF to THF, no dTMP
-can't make DNA
-same as methorexate but works on prokaryotes. Inhibits prokaryotic dihydrofolate reductase
-antibiotic, prok cant make DNA
-structural analog of PABA
-competitive inhibit of bacterial production of folic acid
-inhibits PRPP amidotransferase
-anti tumor drug that's inhibits ribonucleotide reductase
-blocks ribonucleotide conversion into deoxyribonucleotide
-can treat sickle cell too
-inhibits thymidilate synthase
-no methylation of dUMP, so no dTMP
Derivatives are used as carbon donors, methyl groups
What is adenosine deaminase important for?
Adenosine deaminase deficiency
-Affects T and B cells
Treatment for adenosine deaminase deficiency
-bone marrow transplant
-landmark treatment with gene therapy
Converts purine excretion pathway intermediate (xanthine) to uric acid
Xanthine oxidase deficiency
-Overproduction of uric acid
How do you treat xanthine oxidase deficiency?
Slight deficiency of HGPRT
Severe deficiency in HGPRT
Forces salvage purines to be excreted
100% excretion as uric acid accumulates dramatically causing Lesch-Nyah's syndrome
How are nucleotides linked together in nucleic acids?
How do nucleus acid strands associate with each other?
Antiparallel via base pairing using hydrogen bonds
What are the purines?
What are the pyrimidines
How many bonds in GC paring?
3 hydrogen bonds
How many bonds in AT/AU bonds?
2 hydrogen bonds
DsDNA with a high GC content
Requires higher melting temp
DsDNA with high AT content requires
Lower melting temp
A%=T%, C%=G%, A%+T%+G%+C%=100%
-cuts both strands to INTRODUCE supercoils and separate linked replicated DNA
What inhibits DNA gyrase?
Semiconservative DNA replication
1 parent strand
1 new strand
Origin of replication in prokaryotes
1 origin of replication
Origin of replication in eukaryotes
High AT content, easy to melt
Bi directional replication
Run in opposite directions with replication fork
Area where DNA helicase opens the two strands
single stranded binding proteins (SSBs)
-nick in 1 strand
-nick in 2 strands
What direction is DNA polymerized?
Requires RNA primer
-produced continuously 5'-3'
Short stretches of replicated DNA formed as the replication fork moves upstream of the origin of replication for that strand
Adds rNTPs to form a primer and 3'-OH site for DNA polymerase activity
Primase in eukaryotes
Is part of DNA polymerase
Seals all the nicks, form phosphodiester bonds
Telomerase is a reverse transcriptase that extends the ends of eukaryotic DNA using RNA as a template to function as a DNA polymerase
What is the disease associated with strand directed mismatch repair?
HNPCC (hereditary nonpoltposis colorectal cancer)
-terminally differentiated cell starts having telomerase activity
Cause and DNA defect associated with xeroderma pigmentosum
Thiamine diner causes by UV light
-cant fix damage
-Cant repair thiamine dimers
DNA replication overview
-initial strand separation (high AT content)
-SSB proteins prevent reannealing
-helicase unwinds DNA at the replication fork
-topoisomerase relieves supercoiling ahead of fork
-leading strand synthesized continuously
-lagging strand synthesized discontinuously
-primase lays down an RNA primer to being each new strand
-Pol III extends the leading and lagging strand
-Pol I removes RNA primers and replaces them with DNA
-DNA ligase seals the nick in the strands
Transcription: sigma factor
Recognizes promoter sequence in prokaryotic RNA polymerase
Transcription: core enzyme
Gets recruited and does transcription
What is sigma factor + core enzyme?
Binds and inhibits core enzyme
Prokaryotic promoter sequences
Eukaryotic promoter sequence
Shine dalgarno sequence
Start site for translation in prokaryotes. Polycistronic
Specific to prokaryotes
What are the two ways that translation terminates in prokaryotes
GC stem loop, poly U tail
Systemic lupus erythmatosus
-dsDNA and snRNPs are identified by the adaptive immune system, young females, weakness and joint pain, butterfly rash
-toxin from the death cap mushroom causes 95% of mushroom fatalities
-toxin functions by binding RNA polymerase II and inhibits transcription/ mRNA synthesis in eukaryotes
UGA, UAA, UAG
Ribosomes translating secretory proteins
Are targeted to the ER where they continue to translate the protein into the ER.
-hydrophobic peptide signal emerging from the ribosome plays a role in this