AP BIO - Prokaryotic Gene Regulation

What is NOT an accurate difference between the organization of prokaryotic genomes vs. eukaryotic genomes?

• Prokaryotes possess a single circular chromosome whereas eukaryotes possess multiple linear chromosomes

• Prokaryotes do not organize their DNA around histones, while eukaryotes do

• Prokaryotes can have plasmids while eukaryotes cannot

• Prokaryotic genomes contain operons whereas eukaryotic genomes do not

A cluster of genes in a prokaryote that code for proteins all performing related functions in the cell is called a...

• Regulatory Sequence

• Distal Control Element

• Open Reading Frame (ORF)

• Operon

An operon is best defined as...

• transcription and translation happening simultaneously

• a group of genes that share the same operator and promoter in a prokaryote

• polycistronic mRNA

• a gene that requires activation by a transcription factor to be expressed.

A structural gene...

• turns other genes on or off

• codes for proteins to be translated in the cell

• is a sequence of nucleotides where regulatory proteins bind

• codes for cell parts that provide rigidity to the cell

Tags

NGSS.HS-LS1-1

A researcher is studying a particular operon and notices that under very specific environmental conditions, the repressor is bound to the operator. The most reasonable conclusion is that...

• the environment dictates that the structural genes within the operon should not be transcribed

• the regulatory gene coding for the repressor protein must contain a mutation

• the operon is an inducible system

• the structural genes within the operon must not be essential for the bacterium's survival

If a researcher studying an inducible operon system in a particular strain of bacteria suspects that the operator sequence might have experienced a loss-of-function mutation, what experiment would provide evidence to support the hypothesis?

• Artificially synthesize proteins using the structural genes of another population of similar bacteria and then insert these into the cell. Observe whether the operon turns off in response.

• Use restriction (cutting) enzymes to cut out the operator and see if the operon regains function.

• Induce a mutation in the promoter sequence as well and observe whether the structural genes can be transcribed.

• Bioengineer a plasmid containing an unmutated copy of the operator and insert it into a bacterium. Ensure there are no inducers in the cell and observe whether a repressor binds the operator.

Tags

NGSS.HS-LS1-1

NGSS.HS-LS3-2

What is true about this operon?

• The regulatory gene codes for protein A.

• RNA polymerase binds to a sequences of nitrogen bases called the operator.

• Four RNA polymerases are required to work on this operon --- one for each structural gene.

• The mRNA transcribed is polycistronic (containing nucleotide sequences containing multiple start/stop codons and coding for more than one protein)

Tags

NGSS.HS-LS1-1

What DNA base sequence in an operons is responsible for holding the genetic information for the making of the operon repressor

• Regulatory Gene

• Promoter

• Operator

• First Structural Gene

Reorder the following steps to illustrate how an inducible operon system is turned on.

• RNA polymerase binds the promoter and the inducer binds the repressor, which unbinds from the operator.

• RNA proceeds past the operator and moves along the structural genes transcribing mRNA.

• A polycistronic mRNA is produced at the end of transcription.

• Multiple ribosomes work on the mRNA strand to translate the structural proteins.

• The newly synthesized proteins carry out a related function in the cell.

Match the following.

Groups:

(a) Inducible Operon System

,

(b) Repressible Operon System

• Turned off by the build up of a COREPRESSOR.

• Turned on by the presence of an INDUCER.

• Allows for the synthesis of enzymes only when needed.

• The operator is usually free of the repressor.

• The operator is usually bound by the repressor.

• Can be activated by small molecules that interact with the repressor.

• Example includes the lac operon.

• Facilitates the breakdown of lactose when it is present.

• Facilitates the synthesis of tryptophan when it is absent.
• Regulates the synthesis of enzymes continuously unless a corepressor is present.

• Example includes the trp operon.
• Is normally "on" but can be turned "off".

• Can be inhibited by small molecules that interact with the repressor.
• Is normally "off" but can be turned "on".