BIOM-360 Lecture Notes - Lecture 26: Origin Recognition Complex, Housekeeping Gene, Reverse Transcriptase
2 May 2018
School
Department
Course
Professor
Cryptosporidium and
Repression → Negative Control
Induction → Positive Control
DNA Replication
Initiation occurs at multiple sites in eukaryotic chromosomes.
Marked by origin recognition complex (ORC) proteins.
Start in nucleus, move into cytoplasm.
Multiple sites of origin in eukaryotes.
Bacterial DNA is circular, whereas eukaryotic DNA is linear.
Based on AA similarity, eukaryotes and archaea share similar DNA polymerases.
Telomeres and Telomerases
(Enzymes that add the telomeres to help with problem-solving)
Telomeres help us avoid susceptibility to enzymes.
Don’t want to destroy what we’ve already created.
Ends of linear chromosomes
Are susceptible to DNases.
Sometimes fuse to other DNA molecules and do not segregate properly.
Do not have an open 3’ hydroxyl for DNA synthesis by DNA polymerase.
Magic Recipe of Telomerases:
Internal RNA template
Enzyme that helps with reverse transcription.
Rich in guanine, lots of Gs.
Archaeal DNA Replication
Archaea are referred to as “hybrid”
This is actually incorrect… why?
Chromosomes are of similar size and shape compared to bacteria.
Archaea have histones like eukaryotes.
Most with a single origin of replication, but some with multiple
DNA polymerase shares similarity with eukaryotes.
In eukaryotes, transcription occurs in the nucleus.
mRNA must translocate to the cytoplasm, where ribosomes are present for translation.
Promoter TATA present → highly regulated genes
TATA absent → Housekeeping gene
Document Summary
Initiation occurs at multiple sites in eukaryotic chromosomes. Bacterial dna is circular, whereas eukaryotic dna is linear. Based on aa similarity, eukaryotes and archaea share similar dna polymerases. Telomeres and telomerases (enzymes that add the telomeres to help with problem-solving) Don"t want to destroy what we"ve already created. Sometimes fuse to other dna molecules and do not segregate properly. Do not have an open 3" hydroxyl for dna synthesis by dna polymerase. Chromosomes are of similar size and shape compared to bacteria. Most with a single origin of replication, but some with multiple. In eukaryotes, transcription occurs in the nucleus. mrna must translocate to the cytoplasm, where ribosomes are present for translation.
