Exam 3 - Lecture 16 Flashcards
archaea are like bacteria in _________/_____________
looks/architecture
archaea are similar to eukaryotes in the __________ that replicates and expresses archaeal genomes
machinery
what three things does DNA polymerase require?
- template
- primer
- dNTPs
are eukaryotic chromosomes linear, circular, or both?
linear
eukaryotic chromosomes are wound around _________
histones
how many origins of replication do eukaryotes have?
multiple
how many DNA polymerases are responsible for eukaryotic DNA replication? what are they?
3
- polymerase alpha-primase
- polymerase epsilon
- polymerase delta
what is the role of polymerase alpha-primase?
lays down a RNA/DNA hybrid starting point
what is the role of polymerase epsilon?
synthesizes the leading strand
what is the role of polymerase delta?
synthesizes the lagging strand
what are three problems presented by linear DNA molecules?
- chromosome end may be digested by DNases
- DNA ends can fuse with other DNA molecules
- the “end replication problem” of linear DNA replication
what are telomeres? what base are these regions rich in?
- repetitive DNA sequences at the ends of chromosomes
- rich in guanosine bases (called the “G-tail”)
what are telomerases and their functions?
- ribonucleoprotein complex enzyme that forms telomeres and maintains them
telomerase has an _________ _____ ___________ that partially matches the G-tail sequence
internal RNA template
what is the starting point for telomerase DNA synthesis?
the 3’-OH of the G-tail
what activity of telomerase allows for the increase of the length of the G-tail?
reverse transcriptase activity
what shape are archaeal chromosomes?
circular
true or false: some archaea have histones associated with their chromosomes.
true!
do most archaea have a single or multiple origins of replication?
most only have one origin of replication
archaeal replisome proteins are similar to:
eukaryotic ones
how many RNA polymerases do bacteria have?
just one
eukaryotic transcription occurs in the _________ and RNA transcripts must be moved to the __________
nucleus; cytoplasm
true or false: eukaryotic genes are spliced.
true
true or false: eukaryotic transcription and translation are coupled.
false
how many major eukaryotic RNA polymerases are there?
three: RNA pol I, II, & III
what is the role of RNA polymerase I?
catalyzing rRNA synthesis
what is the role of RNA polymerase II?
catalyzing mRNA synthesis
what is the role of RNA polymerase III?
synthesizes tRNA molecules
what elements make up the core promoter in eukaryotic transcription?
- TATA box
- BRE (TFIIB recognition element)
- Inr (initiator element)
- DPE (downstream promoter element)
what is the difference between the eukaryotic and archaeal promoters?
- archaea don’t have a DPE
- their BRE and TATA boxes are at different base pair locations
how many sigma factors do archaea and eukaryotes have?
they don’t have any
what do eukaryotes and archaea use instead of sigma factors?
transcription factors (TFs)
what are the modifications made to initial transcripts before they are ready to be translated?
- 5’ cap of 7-methylguanosine added
- removal of introns/splicing together exons
- addition of 3’ poly-A tail
introns are removed by a large complex of proteins and RNA molecules unique to eukaryotes called the:
spliceosome
what are the two fates of lariats (spliced introns)?
- degradation
- processing into ncRNA
a single eukaryotic gene can code for different final proteins due to:
alternative splicing
how many domains in alternative splicing found?
just one: eukaryotes (the others don’t really get spliced at all, so)
approximately how long is the 3’ poly-A tail?
200 nucleotides long
what are three similarities that archaea have with eukaryotic transcription?
- RNA pol resembles RNA pol II
- archaeal promoters and binding of RNA pol
- no sigma factors
what are four similarities that archaea have with bacterial transcription?
- transcription occurs in cytoplasm
- coupling of transcription/translation
- mRNA is polycistronic
- introns are rare
which requires more initiation factors: eukaryotic or bacterial translation?
eukaryotic translation
when the initiator tRNA interacts with the 40S subunit in eukaryotic translation, what subunit is formed?
43S subunit
when is the 60S subunit recruited to the 43S subunit?
when the 43S subunit finds a start codon on the activated (bridged) mRNA
what is a polysome? what domain of life can it be obsevred in?
- polysome: more than one ribosome translating the same mRNA molecule
- observed in eukaryotes
what is the first codon in archaeal translation?
methionine
true or false: archaea do not have polycistronic transcripts.
false, they certainly do
true or false: archaeal transcription and translation are coupled.
true
what are the three levels at which regulation of cellular processes can take place in all three domains of life?
- transcriptional
- translational
- posttranslational
what are two transcription activator binding sites? do they act near or far from the promoter of the gene being regulated?
- upstream activator sequences (UASs); act near the promoter
- enhancers; act from a distance
what are transcription repressor sites called? do they act near or far from the promoter of the gene being regulated?
silencers; act from a distance
match the following:
- acetylation of histones
- methylation of histones
a. represses transcription
b. promotes transcription
1b
2a
name the six levels of eukaryotic gene regulation.
- transcription initiation
- splicing efficiency
- mRNA trafficking
- mRNA stability/degradation
- translational rate
- post-translational modification
