Quiz 2 Flashcards
What is the difference between DNA polymerase I and III?
DNA Polymerase III is the main enzyme for DNA synthesis, adding nucleotides in the 5’ to 3’ direction and proofreading with 3’ to 5’ exonuclease activity. DNA Polymerase I removes RNA primers with 5’ to 3’ exonuclease activity and replaces them with DNA.
Is DNA polymerase III an exonuclease that removes primers?
No, DNA Polymerase III cannot remove primers. DNA Polymerase I removes primers using 5’ to 3’ exonuclease activity and fills the gaps with DNA.
Does primase synthesize small pieces of RNA to start synthesis of new DNA strands?
Yes, primase synthesizes small RNA primers that provide a starting point for DNA polymerase to initiate DNA synthesis.
What is the difference between topoisomerase II and IV?
Topoisomerase II (DNA gyrase) relieves supercoiling ahead of the replication fork. Topoisomerase IV separates newly replicated daughter chromosomes (decatenation) at the end of replication.
What cuts DNA to release daughter chromosomes and reseals DNA?
Topoisomerase IV cuts intertwined DNA strands to release daughter chromosomes and reseals the DNA.
What are two structural features of mRNA that are needed by eukaryotic cells but not by bacterial cells? What purpose do these features serve?
The 5’ cap protects mRNA from degradation and helps ribosomes recognize mRNA for translation. The 3’ poly-A tail stabilizes mRNA and aids in its export from the nucleus to the cytoplasm.
Besides binary fission, name and describe another way bacterial cells can divide.
Bacterial cells can divide by budding, where a small bud forms on the parent cell, receives a copy of the DNA, and eventually separates as a new, independent cell.
Does primase synthesize small pieces of RNA?
Yes, primase synthesizes small RNA primers that initiate DNA replication by providing a starting point for DNA polymerase.
Where does the initiation of DNA replication occur?
At the origin.
Where does the initiation of transcription occur?
Occurs at the promoter
When does elongation in translation occur?
When tRNAs bring in amino acids according to anticodon/codon complementary base pairing.
When does elongation in transcription occur?
Occurs when ribonucleotides are added in a 5’ to 3’ direction on the antisense strand of the DNA.
When does termination in DNA replication occur?
Occurs when a termination sequence is reached in the chromosome.
When does initiation of translation occur?
When tRNAs bring in amino acids according to anticodon/codon complementary base pairing.
When does elongation in transcription occur?
Occurs when ribonucleotides are added in a 5’ to 3’ direction on the antisense strand of the DNA.
When does termination in DNA replication occur?
Occurs when a termination sequence is reached in the chromosome.
Where does initiation of translation occur?
Occurs at the start codon
Define microbial ecology
Studying relationships between microbes and their environments
Define community.
Interactions between different species within a community
Define parasitism.
One species benefits while the other is harmed.
Define mutualism.
Both species benefit.
Define commensalism.
One species benefits while the other is unaffected.
Define neutralism.
Neither species is affected
Define symbiosis.
Interactions between different species within a community.
