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The Cell Cycle: G1 è S è G2 è M Cyclins
and cyclin-dependent
kinases
Evolution of MITOSIS in
Eukaryotes
TELOMERES = ? rich in G and T bases (species-specific sequence) LAGGING STRAND SYNTHESIS ?? Telomerase = CATALYTIC ribonucleoprotein
See TELOMERASE animation here! See another TELOMERASE animation here! Carol Greider Awarded Nobel Prize
NITROGENOUS BASE (URACIL replaces Thymine) + RIBOSE (5C Sugar) + PHOSPHATE RNA is synthesized as a SINGLE-STRANDED
molecule; but can become varied 3-D conformation and multi-functional RNA World?? TRANSCRIPTION = RNA synthesis DNA:RNA hybrid = heteroduplex
See RNA Polymerase II animation here PROKARYOTES: one RNA polymerase + co-factors E. coli s 70 vs. human RAP 30/74 EUKARYOTIC RNA Polymerases =
Eukaryotic Transcription Control Factors e.g.
The NUCLEOLUS: rRNA synthesis & processing [except 5S rRNA segment] MULTIPLE COPIES of rDNA genes with INTERGENIC SPACER SEQUENCES tandemly repeated genes (» 7,000,000 rRNA copies/day)
processing via snoRNAs (e.g. U3) and snoRNPs =
small nucleolar RNAs S = SVEDBERG UNITS Þ Coefficient of Sedimentation
Intact EUKARYOTIC RIBOSOME
= 80S ribonucleoprotein complex Intact PROKARYOTIC RIBOSOME = 70S (50S + 30S) PRIMARY BINDING PROTEINS and SECONDARY BINDING PROTEINS POLYSOMES = ??
POLYCISTRONIC vs. MONOCISTRONIC mRNA SYNTHESIS and PROCESSING of EUKARYOTIC mRNA Þ the genetic message Eukaryotic RNA Polymerase II Þ “TATA Box” Many GTFs [general transcription factors] Heterogeneous Nuclear RNA = hnRNA (= pre-mRNA)
POST-TRANSCRIPTIONAL MODIFICATIONS small nuclear RNAs = snRNAs = U1 - U8 (and
counting) ("Uridine-rich")
The 5’ (trimethylgauanosine) M3G Cap for snRNP transport into the nucleus.
SYNTHESIS and PROCESSING of EUKARYOTIC tRNA Þ the amino acid carriers MULTI-GENE CLUSTERS RW Holley and the "CLOVERLEAF" configuration (3-D)
Nucleotidyl Transferase = ?? Dihydrouridine Arm (DHU) Þ AA recognition TYC Arm Þ ribosomal recognition Anticodon Arm Þ complementary to mRNA codon variable arm Þ [enzyme recognition??] INVARIANT vs. SEMI-INVARIANT BASES
SEE 3-D tRNA: CLICK HERE Þ Crick: WOBBLE HYPOTHESIS
RNase P (E. coli) Þ precursor tRNA processing: catalytic RNA snRNA M1 = Human mitochondrial rRNA and catalytic RNP = (ribonucleoprotein)Altering Amino Acid after tRNA loading Þ ?? RIBOZYMES
= catalytic RNA
pre-mRNA and pre-rRNA processing; (endonucleases, ligase, kinase, etc.) pre-mRNA and pre-rRNA processing snRNPs and petidyl transferase ® catalytic moiety = RNA Group I - guanosine; "cyclized" rRNA; variable sequence, similar shape Group II - highly conserved; Lariat formation GUIDE RNAs in Kinetoplastid flagellates RNA Þ CATALYTIC and SELF-REPLICATING
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Amino Acid Arm Þ
CCA at 3’ end 
