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The two double strands in DNA have ___ base sequences and form a _____
Complementary ; double-helix
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What are the two types of DNA supercoiling and which is found predominantly in nature?
Negative and positive; Negative found in nature
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Transcription begins at the ____ in Prokaryotes
Promoter region
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The ____ region signals the start of RNA synthesis in Prokaryotes
Promoter
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Stop codons are sometimes called ____, since there is no charged tRNA for the stop codons
Nonsense codons
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If the enzyme primase was mutated, what would be the effect on DNA replication?
No synthesis of RNA primer
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What is an operon?
Group of related genes that are transcribed together to give a single polycistronic mRNA
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A group of related genes that are transcribed together to give a single polycistronic mRNA is called the ____
Operon
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For a bacterial genome, which factors are considered to predict a start codon?
-10 region, -35 region and Shine Dalgarno sequence
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In an open reading frame, the stop codon is found where?
The first encountered codon with a stop sequence
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For DNA replication to begin, what is required?
An RNA primer
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What is a codon?
A triple of bases on an mRNA molecule
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On the leading strand, DNA synthesis occurs ____ and on the lagging strand, DNA synthesis occurs ____
Continuously ; discontinuously
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DNA is the template for _____ and ____ while mRNA is the template for ____
Replication ; Transcription ; Translation
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DNA Polymerase I and III have ____ exonuclease activity while DNA Polymerase I also has ____ exonuclease activity
3' to 5' ; 5' to 3'
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DNA polymerase I and III have ____ polymerase activity
5' to 3'
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Which type of regulation controls the amount of enzyme?
Transcriptional and translational
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Which type of regulation controls the activity of pre-existing enzymes?
Post-translational regulation
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Transcriptional and translational regulation control the _______ while post-translational regulation control the ____
Amount of enzyme ; activity of pre-existing enzymes
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Induction is a _____ control of transcription
Negative
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Repression is a _____ control of transcription
Negative
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What are effectors?
Collective term for inducers and corepressors
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What is the positive control of transcription?
Activator proteins bind to certain DNA sequence called activator binding site
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What is the activator binding site?
A DNA sequence that activator proteins recognize and bind to in a positive control
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In a negative control, what happens when an inducer binds to the repressor?
The genes are transcribed
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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
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Phosphorylated sensor kinase is involved in activation of _____ by providing the phosphate group
Response regulator
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What is a regulon?
Multiple operons controlled by the same regulatory protein
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In diauxic growth, lactose ____ the synthesis of b-galactosidase
Induces
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What happens in diauxic growth after glucose is exhausted?
There is a lag phase due to the synthesis of b-galactosidase
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In diauxic growth, when growth resumes on lactose, growth rate is ___ than that on glucose
Slower
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Why can't attenuation be found in Eukaryotes?
Because transcription and translation of Eukaryotes are uncoupled
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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
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What is plasmid curing?
A process by which plasmids from host cells can be removed
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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
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What are chaperonins?
Enzymes that assist in polypeptide folding but are not incorporated into proteins
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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
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Mitosis in prokaryotic cells happens through the process of ____
Binary fission
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RNA interference (RNAi) cleaves ____ and is found excusively in ____
dsRNA ; Eukaryotes
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What is the major application of RNA interference (RNAi) in science?
It is used in gene silencing
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In Eukarya, what are exons?
Coding regions of DNA
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In Eukarya, what are introns?
Non-coding regions of DNA
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How do prokaryotes manage longer DNA replication time than doubling time?
By utilizing multiple replication forks
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DNA replication proceeds ____ and transcription proceeds _____
5' to 3' ; 5' to 3'
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____ in the small subunit of ribosome recognizes the Shine Dalgarno sequence
16S
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Why is a polysome more efficient than a single ribosome?
Because it can simultaneously translate a single mRNA faster
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What are release factors?
Result in termination of protein synthesis (translation) in prokaryotes
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______ result in termination of protein synthesis in prokaryotes
Release factors
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In Eukaryotes, the genes for the large rRNAs are transcribed by _____
RNA Polymerase I
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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
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Which domain has telomeres and telomerase?
Eukarya
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What is the first acid in a bacterial protein?
Formylmethionine
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What are ribozymes?
RNA molecules with enzymatic activity
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RNA molecules with enzymatic activity are called _____
Ribozymes
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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
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What are transposable elements?
Sequences or genes in DNA that can be inserted into other DNA and play a role in genetic variation
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The fragments of DNA on the lagging strand are called?
Okazaki fragments
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In DNA replication, after removing the RNA primer, _____ fills in the gap
DNA Polymerase I
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What is the function of DNA Lygase?
Seals nicks in DNA
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_____ excises the RNA primer during DNA replication
DNA Polymerase I
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In termination of transcription, where does intrinsic termination occur?
Both Eukaryotes and Prokaryotes
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In termination of transcription, where does Rho-dependent termination occur?
Only in Prokaryotes (and requires energy)
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In Archaea, where does transcription take place?
Cytoplasm
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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
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Archaeal and eukaryotic DNA is wound around clusters of histones, forming structures known as _____
Nucleosome (or chromatin)
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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
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What is quorum sensing?
Mechanism by which bacteria assess their population density and controls gene expression based on cell density
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