All High School Biology Resources
Example Questions
Example Question #1 : Understand Regulation Of Transcription
What is the function of RNA polymerase in prokaryotes?
Transcribe RNA from a DNA template
Translate RNA to protein
None of the other answers
Replicate DNA during cell division
Repress transcription by binding operators
Transcribe RNA from a DNA template
The correct answer is transcribe RNA from a DNA template. RNA polymerases are DNA-dependent, meaning that they require a DNA template; however, the new daughter strand that they create is composed of RNA. This RNA will then be translated into a functional protein by prokaryotic ribosomes.
Example Question #1 : Understanding Prokaryotic Genes
Which of the following is true of Rho-dependent transcription termination in prokaryotes?
None of the other answers
Rho unwinds the DNA-RNA helix at the transcription bubble
Rho uses GTP as a source of energy
Rho is a nuclease that terminates transcription by cutting template DNA
Rho attaches to a Rho recognition site on the DNA template
Rho unwinds the DNA-RNA helix at the transcription bubble
Rho attaches to a Rho recognition site on the mRNA strand and uses ATP to move along the mRNA strand towards RNA polymerase. When RNA polymerase pauses at the terminator, Rho unwinds the DNA-RNA hybrid. RNA polymerase, Rho, and the newly synthesized mRNA are released.
Example Question #1 : Understanding Prokaryotic Genes
Prokaryotic genes are often grouped together based on function. What are these groups of genes called?
Clusters
Promoter sequences
Operator sequences
Linked genes
Operons
Operons
Bacteria organize some of their genes into operons. Operons contain genes of a similar function grouped together, and these genes are all transcribed together. For example, the lac operon involves the three genes required for breaking down lactose. There is no point in only transcribing one or two of the three genes since they are all required to break down lactose. Thus, they are under the control of a single operator and are all transcribed when the operator is active.
Example Question #11 : Genes And Dna
Bacterial plasmids can __________.
be present in multiple copies
carry antibiotic resistance genes
transfer between bacterial cells
All of these
integrate into the bacterial genome
All of these
Plasmids are small pieces of DNA that are not part of a bacteria's genome. The genes contained on plasmids are not necessary for proper function of the bacteria. However, bacterial plasmids can carry genes to confer antibiotic resistance, and commonly do. Plasmids can be transferred between bacteria via conjugation, and can be integrated into their genomic DNA.. Plasmids are usually present in more than one copy per cell.
Example Question #2 : Understanding Prokaryotic Genes
Which of the following technological advances allows for the creation of a “recombinant plasmid”?
Restriction endonucleases
Viral vectors
Sanger sequencing
cDNA libraries
Watson-Crick base pairing
Restriction endonucleases
Restriction Endonucleases, or otherwise known as restriction enzymes, allows biologist to “cut and paste” different DNA sequences together. The use of restriction endonucleases is critical for the creation of recombinant plasmids. Viral vectors is incorrect, as viral vectors are useful in the application of recombinant DNA plasmids, delivery to host cell, but not in forming.
Example Question #1 : Understanding Prokaryotic Genes
A mutation in the bacterial cell escherichia coli makes it unable to break down the sugar lactose. Which of the following is not a potential mutation that could result in this phenotype?
A point mutation in the LacZ gene that abolishes enzyme activity
A mutation in the region DNA polymerase binds to in the promoter
A frameshift mutation in the LacZ coding region
A mutation in the operator that blocks the activator from binding
A mutation in the region DNA polymerase binds to in the promoter
DNA polymerase is not involved in the process of transcription. The incorrect answer could be corrected if it was rewritten as "a mutation in the promoter region where the RNA polymerase binds to."
Example Question #2 : Understanding Prokaryotic Genes
When a repressor binds to the __________, the LacZ gene does not get expressed.
promoter
terminator
operator
gene
operator
The region of a gene where activator/repressors bind in prokaryotic organisms is called an operator. The protein that's bound to the operon strongly influences the level of gene expression.
Example Question #1 : Understanding Gene Regulation
A protein that binds to a DNA sequence and reduces transcription of a target gene is referred to as __________.
an activator
an insulator
a repressor
an inhibitor
a repressor
A repressor is a transcription factor that negatively regulates expression of a target gene. An activator is a transcription factor that enhances expression of a target gene. Activators and repressors often bind to the same genomic sequence to precisely regulate transcription.
An inhibitor is a factor that modulates a biological or chemical process, such as a cell signaling pathway or an enzymatic reaction, but does not generally bind directly to DNA. An insulator is a protein that forms boundaries between active and inactive genomic regions, but generally does not have a direct effect on a target gene.
Example Question #92 : Genetics Principles
What is the functional unit in which numerous adjacent genes are under the control of the same promoter and regulated by the same operator?
Exon
Operon
Transcription factor
Intron
Enhancer
Operon
The correct answer is operon. Found in prokaryotes and a few eukaryotes, operons allow transcription and translation of all the genes downstream of a promoter simultaneously. This is advantageous because these organisms are able to express a subset of related genes rapidly in response to external or internal stimuli.
Example Question #131 : Genetics And Evolution
Fill in the blanks with the best answers:
__________ are DNA segments that carry information that will ultimately not be transcribed into mRNA. These regions occur between __________, which are the DNA segments containing the genes to be transcribed and translated.
Introns . . . codons
Exons . . . histones
Introns . . . exons
Exons . . . introns
Introns . . . proteins
Introns . . . exons
This is simply a matter of vocabulary. Introns do not contain coding sequences, while exons do. "Intron" comes from the word "intragenic," meaning between genes, and therefore between exons. During post-transcriptional modification, introns are spliced out of the initial RNA transcript.
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