Module 10 - Microbial Genetics Flashcards
What is the genome
All DNA present in a cell or a virus
What are the two types of genome? What has what?
Haploid 1N: Bacteria & Archaea
Diploid 2N: Eukaryotes
What is a genotype?
A specific set of genes an organism possesses
What is a phenotype?
A collection of observable characteristics
What is transcription
A process that yields an RNA copy of specific genes (mRNA)
What is translation
Decoding mRNA to synthesize a polypeptide
What is replication
DNA makes a copy of itself
What is the central dogma
The flow of genetic information, DNA->RNA->Protein
What are the 3 differences between DNA and RNA
-Deoxyribose vs ribose
-Bases AGCT vs AGCU
-Single vs double stranded
How is prokaryotic DNA organized
Circular double helix / supercoiled DNA
How is eukaryotic DNA organized
Chromatin where it is associated with histones (nucleosome)
DNA synthesis is _____ conservative and why?
semi, because half of each daughter is made of the parent and the other half of each is a new strand
What type of prokaryote may have more than one origin of replication?
Archaea
Replication in prokaryotes is (direction)
Bidirectional
What is DNA polymerase
Catalyzes the synthesis of the complementary strand of DNA
What direction is DNA synthesis
5’ to 3’
What are the three requirements of polymerase to synthesize DNA
Template, primer, dNTPs (nucleotides)
What is DNA polymerase III
Protein complex, catalyze synthesis, proof read, bind both strands of DNA at the same time. Proofreads
What does DnaB do
Breaks the H bonds between strands essentially splitting the helix
What does DnaA do
Binds to the origin of replication and directs DnaB to break the bonds
What is Helicase (replisome)
Unwind DNA strands
What are SSBs (replisome)
Hold the two strands apart
What is topoisomerase
Relieve the tension caused by rapid unwinding by knicking the strands
What is primase
Creates a primer at the origin of replication
How is the leading strand synthesized
Polymerase III synthesizes it continuously from 5’-3’
What is the leading strand
The top strand leading from 5’-3’
How is the lagging strand synthesized
Synthesized using small okazaki fragments. Multiple primers needed
What is the lagging strand
Bottom strand, 3’-5’
What is Ligase
reattaches the Okazaki fragments
What are the 3 steps in transcription
Initiation: unwinding DNA
Elongation: RNA synthesis, complementary nucleotides added
Termination: terminator sequence reached
What is used transcription in bacteria
polycistronic mRNA
What is a gene
A nucleic acid sequence that codes for a polypeptide
What is a codon
A code for a single amino acid
Where do we start reading codons
Initiation - AUG
What is the coding region
The region that begins with AUG and ends with a stop codon
What is a holoenzyme
Core enzyme + sigma factor
Explain 7 steps of DNA replication, direction, and location
- helicase breaks helix 2. ssb stabilizes and prevents reannealing 3. primase makes the primer to guide polymerase iii 4. polymerase iii places nucleotides 5. polymerase i replaces primers 6. ligaments connects okazaki fragments 7. topoisomerase relieves tension, 5’-3’ nucleus
What is initiation in transcription, location, direction
RNA polymerase bonds to promoter indicated by the TATA or pribnow box. nucleus or cytoplasm 5’-3’
What is elongation in transcription
RNA polymerase unwinds DNA and slides along the template strand adding nucleotides
What is termination in transcription
Sequence in DNA causes a loop OR rho causes RNA polymerase to dissociate
How does transcription differ in eukaryotes and prokaryotes
Eukaryotes vs Prokaryotes
nucleus / cytoplasm
TATA / pribnow
Cap & poly A tail / none
Intron splicing / none
monocistronic / polycistronic
What are the 3 things required by DNA polymerase for synthesis
- nucleotides 2. primer 3. template
