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Test Microbiology Chang
Test 3 Chang
The two double strands in DNA have ___ base sequences and form a _____
Complementary ; double-helix
What are the two types of DNA supercoiling and which is found predominantly in nature?
Negative and positive; Negative found in nature
Transcription begins at the ____ in Prokaryotes
The ____ region signals the start of RNA synthesis in Prokaryotes
Stop codons are sometimes called ____, since there is no charged tRNA for the stop codons
If the enzyme primase was mutated, what would be the effect on DNA replication?
No synthesis of RNA primer
What is an operon?
Group of related genes that are transcribed together to give a single polycistronic mRNA
A group of related genes that are transcribed together to give a single polycistronic mRNA is called the ____
For a bacterial genome, which factors are considered to predict a start codon?
-10 region, -35 region and Shine Dalgarno sequence
In an open reading frame, the stop codon is found where?
The first encountered codon with a stop sequence
For DNA replication to begin, what is required?
An RNA primer
What is a codon?
A triple of bases on an mRNA molecule
On the leading strand, DNA synthesis occurs ____ and on the lagging strand, DNA synthesis occurs ____
Continuously ; discontinuously
DNA is the template for _____ and ____ while mRNA is the template for ____
Replication ; Transcription ; Translation
DNA Polymerase I and III have ____ exonuclease activity while DNA Polymerase I also has ____ exonuclease activity
3' to 5' ; 5' to 3'
DNA polymerase I and III have ____ polymerase activity
5' to 3'
Which type of regulation controls the amount of enzyme?
Transcriptional and translational
Which type of regulation controls the activity of pre-existing enzymes?
Transcriptional and translational regulation control the _______ while post-translational regulation control the ____
Amount of enzyme ; activity of pre-existing enzymes
Induction is a _____ control of transcription
Repression is a _____ control of transcription
What are effectors?
Collective term for inducers and corepressors
What is the positive control of transcription?
Activator proteins bind to certain DNA sequence called activator binding site
What is the activator binding site?
A DNA sequence that activator proteins recognize and bind to in a positive control
In a negative control, what happens when an inducer binds to the repressor?
The genes are transcribed
In a two component regulatory system, what is the function of sensor kinase and where is it found?
Detects environmental signal and autophosphorylates ; found in cytoplasmic membrane
Phosphorylated sensor kinase is involved in activation of _____ by providing the phosphate group
What is a regulon?
Multiple operons controlled by the same regulatory protein
In diauxic growth, lactose ____ the synthesis of b-galactosidase
What happens in diauxic growth after glucose is exhausted?
There is a lag phase due to the synthesis of b-galactosidase
In diauxic growth, when growth resumes on lactose, growth rate is ___ than that on glucose
Why can't attenuation be found in Eukaryotes?
Because transcription and translation of Eukaryotes are uncoupled
Which statements correctly describe attenuation?
The tryptophan operon is an example of attenuation
mRNA stem-loop structure and synthesis of leader peptide are determining factors
In attenuation, uncharged t-RNA makes translation stalled
What is plasmid curing?
A process by which plasmids from host cells can be removed
What are the properties of signal sequences?
-usually 15-20 residues long
-found at the beginning of protein molecules
-signal the cell's secretary system
-keep the protein from folding
What are chaperonins?
Enzymes that assist in polypeptide folding but are not incorporated into proteins
What is meiosis?
-Meiosis occurs in sperm cells and reproduction division
-Meiosis is a specialized form of nuclear division and halves diploid number to haploid number
Mitosis in prokaryotic cells happens through the process of ____
RNA interference (RNAi) cleaves ____ and is found excusively in ____
dsRNA ; Eukaryotes
What is the major application of RNA interference (RNAi) in science?
It is used in gene silencing
In Eukarya, what are exons?
Coding regions of DNA
In Eukarya, what are introns?
Non-coding regions of DNA
How do prokaryotes manage longer DNA replication time than doubling time?
By utilizing multiple replication forks
DNA replication proceeds ____ and transcription proceeds _____
5' to 3' ; 5' to 3'
____ in the small subunit of ribosome recognizes the Shine Dalgarno sequence
Why is a polysome more efficient than a single ribosome?
Because it can simultaneously translate a single mRNA faster
What are release factors?
Result in termination of protein synthesis (translation) in prokaryotes
______ result in termination of protein synthesis in prokaryotes
In Eukaryotes, the genes for the large rRNAs are transcribed by _____
RNA Polymerase I
What are the characteristics of riboswitches?
-located at 5' end of mRNA
-analogous to negative control
-similar to protein recognizing a substrate
-found in Eukarya
Which domain has telomeres and telomerase?
What is the first acid in a bacterial protein?
What are ribozymes?
RNA molecules with enzymatic activity
RNA molecules with enzymatic activity are called _____
What are some properties of genetic elements?
-Viruses contain either RNA or DNA genomes
-Plasmids replicate separately from chromosome and most are circular
-Transposable elements can be inserted into other DNA and play a role in genetic variation
What are transposable elements?
Sequences or genes in DNA that can be inserted into other DNA and play a role in genetic variation
The fragments of DNA on the lagging strand are called?
In DNA replication, after removing the RNA primer, _____ fills in the gap
DNA Polymerase I
What is the function of DNA Lygase?
Seals nicks in DNA
_____ excises the RNA primer during DNA replication
DNA Polymerase I
In termination of transcription, where does intrinsic termination occur?
Both Eukaryotes and Prokaryotes
In termination of transcription, where does Rho-dependent termination occur?
Only in Prokaryotes (and requires energy)
In Archaea, where does transcription take place?
What is an open reading frame?
-A sequence (from start to stop codon) of DNA or RNA that can be translated to give a polypeptide
-Usually represents one gene
Archaeal and eukaryotic DNA is wound around clusters of histones, forming structures known as _____
Nucleosome (or chromatin)
What is the function of DNA Gyrase and what group does it belong to?
Introduces supercoils into DNA by making a double stranded break in DNA
Belongs to group of Type II topoisomerase
What is quorum sensing?
Mechanism by which bacteria assess their population density and controls gene expression based on cell density