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There are five principal bases in nucleic acids
A, G, T, C are present in DNAA, G, U, C are present in RNA
Inosine is carbonylatedadenosine
1) Ribonucleotide reductase catalyzes thesynthesis of deoxyribonucleotides
Inhibited by hydroxyurea, which is used as anti-cancer drug
2) Thymidylate synthase catalyzes the methylation of dUTP
Conversion of ribo-to-deoxyribonucleotides
UMP
Defects in the purine salvage pathway cause human diseases
Salvage PathwayActivated ribose (PRPP) + base
Nucleotides
De Novo PathwayActivated ribose (PRPP) + amino acids
+ ATP + CO2 +……….
Nucleotides
Blocked by HGPRT deficiency (Gout, Lesh-Nyhan)
PRPP
Exchange of genetic material during meiosis
Recombination=crossover + exchange of DNA betweentwo DNA double strands
Organization and rearrangement of heavy-chain DNA
V=variableD=diversityJ=joiningC=constant
VDJ recombination allows forantibody diversity
Different classes of immunoglobulin (isotypes) fulfill different tasks
major class major class membrane- unknown against In serum in external bound parasites, secretions allergies
1st lineof defense
Multiple cdks and cyclins regulate passage of mammalian cells through the cell cycle
Restriction point is analogous to START
Cdc2/Cdk1-cyclin BCdc2/Cdk1-cyclin A
Cdk2-cyclin A
Cdk2-cyclin E
Cdk4-cyclin DCdk6-cyclin D
good genes bad genes
proto-oncogenes oncogenesare required for promote uncontollednormal growth growth gain-of-function
mutation (can bepoint mutation, insertion or deletion)
Besides mutations in proto-oncogene/tumor suppressor coding regions, mutationsin gene regulatory elements (promoter) can deregulate the expression pattern
tumor suppressors inactive tumor suppressor
loss-of-functionmutation