The Tryptophan Operon is a Repressible Operon

The tryptophan operon is a repressible operon that is: TERM IMAGE Turned off whenever tryptophan is added to the growth medium. DEFINITION The lactose operon is likely to be transcribed when: TERM IMAGE The cyclic AMP and lactose levels are both high within the cell. DEFINITION For a repressible operon to be transcribed TERM IMAGE which of the following must occur?, RNA polymerase must bind to the promoter, and the repressor must be inactive. DEFINITION Which of the following TERM IMAGE when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?, Inducer DEFINITION What is a promoter? TERM IMAGE Sequence where the RNA polymerase binds and begins transcription. It is upstream of the sequence encoding the protein DEFINITION Which of the following is a protein produced by a regulatory gene? TERM IMAGE Repressor DEFINITION What is a corepressor? TERM IMAGE A small molecule that combines with and activates a repressor produced by a regular gene DEFINITION What is an operator? TERM IMAGE A regulatory sequence that a repressor can bind to DEFINITION What is a regulatory gene? TERM IMAGE Genes that encode a protein involved in regulation of gene expression DEFINITION What has to happen for a gene to be transcribed? TERM IMAGE RNA polymerase, which makes new RNA molecules from a DNA template, must attach to the DNA of the gene. DEFINITION In eukaryotes TERM IMAGE general transcription factors:, Bind to other proteins or to a sequence element within the promoter called the TATA box. DEFINITION What is a TATA box? TERM IMAGE DNA sequence that indicates where a genetic sequence can be read and decoded DEFINITION Two potential devices that eukaryotic cells use to regulate transcription are TERM IMAGE DNA methylation and histone modification. (epigenetic phenomena) DEFINITION Why are viruses obligate parasites? TERM IMAGE They cannot reproduce outside of the host cell DEFINITION Which characteristic is common to all viruses? TERM IMAGE A genome (nucleic acid) enclosed in a protein capsid DEFINITION All viruses contain what? TERM IMAGE A genome and a protein capsid DEFINITION What determines the host range of a virus? TERM IMAGE The receptor protein that is on the cell surface DEFINITION Virulent envelope is made of molecules called? TERM IMAGE Viral glycoproteins that help with attachment to the surface of animal viruses, which are proteins plus carbohydrates DEFINITION Virulent phages undergo what? TERM IMAGE Lytic life cycle DEFINITION Temperature changes are capable of undergoing what? TERM IMAGE Lytic and lysogenic cycles DEFINITION What is the Lytic cycle? TERM IMAGE A large number of phages are released at a time. Results in the death of the host cell DEFINITION What is the lysogenic cycle? TERM IMAGE Replicates the phage genome without destroying the host. The viral DNA molecule is incorporated into the host cell's chromosome. The integrated viral DNA is known as a prophage. Every time the host divides, the phage genome replicates along with the host genome. DEFINITION What is a bacteriophage? TERM IMAGE Viruses that infect bacteria. RNA viruses replication- does not involve the proofreading steps of DNA replication DEFINITION How do prokaryotes reproduce? TERM IMAGE They reproduce by binary fission DEFINITION What is transformation? TERM IMAGE The process in which external DNa form the surrounding environment is taken up by a prokaryotic cell. DEFINITION What is transduction? TERM IMAGE The movement of genes between bacteria by bacteriophages DEFINITION What is conjugation? TERM IMAGE The process where DNA is exchanged between bacterial cells through sex pilus DEFINITION When does tryptophan operon turned off? TERM IMAGE Turned off when tryptophan is added to growth medium DEFINITION What is the lactose operon? TERM IMAGE Inducible operon. Turned on when lactose levels are high within the cell DEFINITION What does the the inducer do to the repressor? TERM IMAGE Binds to the repressor so that the repressor cannot bind to the operator DEFINITION What is a regulatory gene code for? TERM IMAGE Codes for the repressor protein DEFINITION What does a corepressor do? TERM IMAGE Binds to the repressor DEFINITION What does RNA polymerase do? TERM IMAGE Binds to the promoter and transcribes structural genes. DEFINITION What is a repressible operon TERM IMAGE Tryptophane. Always turned on DEFINITION What is an inducible operon TERM IMAGE Lactose. Always turned off DEFINITION What do transcription factors do? TERM IMAGE Help with the transcription of genes DEFINITION What is the TATA box? TERM IMAGE Eukaryotic promoter DEFINITION What is DNA methylation TERM IMAGE Can regulate transcription in Eukaryotic cells DEFINITION What is histone modification in eukaryotic cells? TERM IMAGE They regulate transcription in Eukaryotic cells. DEFINITION What are histones? TERM IMAGE Protein blocks on which the DNA is coiled DEFINITION What does DNA acetylation do? TERM IMAGE It uncoils the DNA so it becomes loosely wrapped and initiates transcription. DEFINITION Gene expression is primarily regulated at what level? TERM IMAGE Transcription DEFINITION What does the operon model attempt to explain? TERM IMAGE Coordinates control of gene expression in bacteria DEFINITION Why are muscle cells and nerve cells different in one species of animal? TERM IMAGE They have different genes that will express in muscle cells and nerve cells DEFINITION What is the significance of gene expression in the organism's survival? TERM IMAGE It allows the organism to adapt and adjust to changes in environmental conditions DEFINITION How does Allolactose induce the synthesis of the enzyme lactase? TERM IMAGE Example of a corepressor. It binds to the repressor protein and allow the protein to change shape so it can no longer bind to the operator and RNA polymerase can then go and bind DEFINITION What starts the transcription of the structural genes in an inducible operon? TERM IMAGE Starts when the pathway substrate is present DEFINITION What is the role of a metabolite that controls a repressible operon? TERM IMAGE To bind to the repressor protein and activate it DEFINITION What is the structure of a virus? TERM IMAGE Protein Capsid, nucleic acid genome DEFINITION What is the host range of a virus TERM IMAGE Proteins on the surface of virus and host cells DEFINITION What does a virulent phage cause/ TERM IMAGE lysis host cell because it reproduces by lytic cycle DEFINITION What happens during the lytic cycle TERM IMAGE The virus infects the host cell and once the cell replicates the virus the host cell explodes and releses more of the virus. DEFINITION What is a temperate phage TERM IMAGE Bacteriaphage that can choose inbetween the lysogenic and lytic cycles DEFINITION Lysogenic cycle TERM IMAGE Uses the host cell to replicate DNA without killing the host cell DEFINITION What is a prophage? TERM IMAGE the genetic material of a bacteriophage, incorporated into the genome of a bacterium and able to produce phages if specifically activated. DEFINITION Why RNA viruses have higher rates of mutation/ TERM IMAGE They do not undergo proof reading DEFINITION What characteristics of electron microscopes make them most useful for studying viruses? TERM IMAGE Shutter wavelength DEFINITION Why are viruses referred to as obligate parasites TERM IMAGE they need a host cell to reproduce DEFINITION What molecules make up the viral envelope? TERM IMAGE Glycoproteins DEFINITION What is Zoonosis TERM IMAGE Rabies and transmission from animals DEFINITION What is a retrovirus TERM IMAGE A virus that is single stranded RNA DEFINITION What does Reverse transcriptase do TERM IMAGE It uses viral RNA as a template for DNA synthesis DEFINITION How does a vaccine work? TERM IMAGE One injects an unactivated virus which helps the body build up antibodies to fight the actual virus when introduced. DEFINITION What are prions? TERM IMAGE Misfolded versions of a normal brain protein DEFINITION How does the flue virus move between species TERM IMAGE In the pig cell, there are two viral strains that undergo genetic recombination which forms a mutation which can infect a birds cell and again gets mutated to infect human hosts. Undergoes two rounds of mutation DEFINITION What is the nucleoid? TERM IMAGE The place where chromosomal DNa is present DEFINITION What is a plasmid? TERM IMAGE A small right shaped extrachromosomal DNA present in prokaryotic cells DEFINITION What is binary fission? TERM IMAGE It is a mode of prokaryotic reproduction DEFINITION What is the F plasmid? TERM IMAGE The plasmid that contains the F factor that codes for the sex pilus DEFINITION What is a F factor? TERM IMAGE a plasmid in certain bacteria that enables transfer of genetic material from a donor cell to a recipient by conjugation, resulting in recombination. DEFINITION What is the Sex pilus? TERM IMAGE an appendage of a male bacterium by which it attaches to a female bacterium, preparatory to the transfer of DNA from male to female. DEFINITION How does the antibiotic resistance spread to other bacteria TERM IMAGE Through the process of conjugation DEFINITION What is the primary source of variation in prokaryotic populations? TERM IMAGE Mutation that leads to variation in prokaryotic populations DEFINITION Why was one of the streptococcus pneumoniae strains in Griffith's experiment called smooth? TERM IMAGE Has a capsule, therefore the cell had a smooth appearance DEFINITION How does a recipient cell get converted into a donor cell? TERM IMAGE Acquisition of the F factor DEFINITION What do R plasmids code for? TERM IMAGE They code for resistance DEFINITION What is the danger in overuse of antibiotics? TERM IMAGE Overuse of antibiotics can select for antibiotic strains of resistant bacteria DEFINITION Difference in how prokaryotic DNA and Eukaryotic DNA are wrapped around proteins TERM IMAGE Eukaryotic is more complex, so they are tightly wrapped. DEFINITION Similarities in prokaryotic and eukaryotic cells TERM IMAGE Cells, Cell membrane, and ribosomes DEFINITION What are the three shapes of bacteria? TERM IMAGE 1. Round - coccus 2. Rod - Cillus 3. Spiral - Spirillum DEFINITION