Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

93 Cards in this Set

  • Front
  • Back
For regulated cells, what are the three ways this is done?
What are unregulated cells (processes?) called?
What are the two places enzyme synthesis can be regulated?
-at translation
-at transcription
What is allosteric inhibition?
-the inhibitor (effector) non-covalently binds to allosteric site (non-active) and causing conformational change adn inhibiition
What is feedback inhibition?
-inhibitor is end product of reaction
-usually inhibits first enzyme (rate-limiting) in pathway
-commonly used in branched pathways
When is enzyme activity completely inhibited?
-when ALL isozymes are inhibited
*different end products can inhibit different isozymes that catalyze the same reaction
What are isozymes?
-enzymes that differ in amino acid sequence but catalyze the same chemical reaction
What are 5 types of Post-translational modifications?
-protein processing
-protein splicing
What is the definition of post-translational modifications?
-multiple mechanisms to alter enzyme activity
What are the two types of phosphorylated proteins?
What else can be regulated with phosphorylated proteins?
+kinases and phosphatases (also by dephosphorylation)
What is adenylation?
-covalent attachment of AMP molecules
-glutamine synthetase
What is protein processing?
-removal of amino acids
-cross linking of polypeptides
What is protein splicing?
-similar to RNA splicing
-removal of internal amino acids
What is phosphorylation?
-addition of phosphate froup to ser, thr, or tyr residue
-most prevalent form of modification in eukaryotes
What is ubiquitanation?
-addition of ubiquitin polypeptide
-leads to proteolysis
How can synthesis of enyzmes respond to environmental factors?
-increased or decreased (induced or repressed)
-level of transcription or coupled transcription/translation
What is enzyme induction?
-catabolic pathways
-enzymes needed to break down a molecule are only synthesized when molecule is present
-molecule (or derivative) acts as an inducer; induction can be under negative and/or positive control
What is enzyme repression?
-anabolic pathways
-enzymes needed to synthesize a molecule are not made if molecule is present
-end-product acts as co-repressor
-repression is only under negative control
What is the operon?
-multiple genes that are coordinately regulated
-contained in a single polycistronic mRNA
-inducible or repressible
What is the regulon?
-multiple genes that are coordinately regulated
-different mRNA's
Describe inducible operons?
-catabolic pathways
-regulates presence of substrate of pathways
-lac operon
Describe repressible operons?
-anabolic pathways
-presence of product
-trp operon
What are proteins that negatively regulate transcription?
How about positive control?
How do repressors regulate transcription?
-negatively control transcription
-bind to DNA sequences (operators) and inhibit RNA polymerase
-inducers and co-repressors enter the cell and bind to repressor
-affect ability to bind to DNA
What do inducers do?
-dissociate repressor-operator binding
-induce repressor-operator binding
Can induction and repression both be negatively controlled by repressors?
How do activators work?
-proteins that induce transcription
-usually interact with RNA polymerase and stabilize transcription initiation complex
-can work with repressors or separately
-most common form of regulation in eukaryotes
-interactions with RNA polymerase can lead to DNA bending
What are two types of DNA-binding proteins?
-repressors and activators
Describe the types of DNA-binding proteins?
-sequence specific
-helix turn helix
-zinc fingers
-leucine zipper
How are DNA-binding proteins sequence-specific?
-specific amino acids in protein recognize specific bases in DNA
-usually in the major groove
Describe DNA binding sites?
-inverted repeats
-palindromic sequences
-multiple structural motifs used by DNA binding proteins
What uses helix turn helix DNA binding proteins?
-prokaryotic repressors
What uses zinc-fingers in DNA-binding proteins?
-eukaryotic regulators
What uses leucine zipper DNA-binding proteins?
-eukaryotic regulators
-holds helices together
What is global regulation?
-catabolite repression
What is a regulon?
-multiple genes coordinately regulated by same environmental signal
-many examples-nutrient utilization, stress responses
What is the glucose effect?
-when glucose is present, E. coli will NOT use other sugars until the glucose is used up
What affect does glucose have on cAMP and transcription?
-glucose present: cAMP levels are low and transcription is not induced
-glucaose absent: cAMP levels are high and CAP-dependent transcription is induced
Describe glucose effect
-catabolite repression
-occurs through transcriptional induction
-catabolite activator protein (CAP) binds to cAMP molecule, then interacts with RNA polymerase
What is the only thing that can use coupled transcription-translation?
-bacteria using attenuation
Describe attenuation.
-translation of short loader peptide affects transcription termination
-only found in prokaryotes
-primarily seen in anabolic pathways such as amino acid biosynthesis
What does the rate of translation determine?
What does this affect?
-availability of charged tRNA molecules
-this affects sexondary structure of mRNA formed
In attenuation, how is transcription affected by tyrptophan?
-terminated with excess tryptophan
-transcription not terminated if tryptophan starved
What is the two-component regulatory system used for?
-signal transduction
What is signal transduction?
-signal from environmental factors are transduced to transcriptional machinery via signaling molecules
What is the two-component system?
-sensor kinase and response regulator
-phosphatase inactivates regulator when signal decreases
How does kinase phosphorylates regulator work?
-it recieves a response from environmental signal and acts either as a repressor or activator of transcription
What are some examples of two-component systems and which bacteria uses them?
-nitorgen fixation by Klebsiella
-sporulation by Bacillus
-osmolarity by E. coli (has 50 two-component systems)
Do east and other eukaryotic microbes have two-component systems?
-no, but they have similar two-component systems and other signal transduction systems
What are the 4 important viruses studied for replication in class?
-Herpes Simplex Virus 1
-Influenza Virus
What are three types of virus replication?
-direct penetration
-membrane fusion
What viruses use direct penetration and what happens here?
-non-enveloped (naked) viruses such as poliovirus
-genome is inserted but capsid remains outside cell
What viruses use membrane fusion and what happens here?
-enveloped viruses such measles and mumps
-viral envelope fuses with plasma membrane
What viruses use phagocytosis?
-enveloped viruses such as herpesvirus
-entire virion is engulfed by phagocytosis
-viral envelope is removed inside cell by uncoating enzymes
What are viral receptors for?
-function in cell to cell or cell to environmentcommunication
-can have multiple other functions
-only cells that contain receptor are infected by virus
What are the different types of receptor classes?
-cell adhesion and cell-cell contact proteins
-complement control protein superfamily
-other proteins
-extracellular matrix components and sugar derivatives
What is the cell structure and receptor class of HIV family?
-cell adhesion and cell to cell contact proteins
-CXCR4 (TM7 family)
What is the cell structure and receptor class of Poliovirus?
-other protiens
-PVR and related proteins HveB and HveC (ig superfamily)
What is the cell structure and receptor class of Influenza?
-extracellular matrix components and sugar derivatives
-sialic acid
How do non-enveloped viruses enter into a bacteria?
-virion binds to cell receptor Pvr
-capsid proteins form a pore for the release of RNA into cells
*RNA may enter at binding site or after pore separates membrane and enters cell
What mediates fusion and entry of virion RNA into a bacteria for membrane fusion?
-viral envelope glycoproteins
How does membrane fusion work?
-once bound to the receptor, the viral genome is delivered across the cellular lipid bilayer
What are some viral envelope glycoproteins?
-CD4 binding
-Exposure of CoR binding site
-Triple-stranded coiled-coil
-Coreceptor binding
-6-helix bundle
What is virus production?
What does this depend on?
-combination of replication of genome and virus assembly
-depends on nucleic acid
What must be considered during animal virus replication?
-how mRNA is synthesized
*only +ssRNA can act as an mRNA for translation, -ssRNA must be transcribed into +ssRNA
-what serves as a template for nucleic acid replication
What is the genome, how is it synthesized, and what molecule is the template for genome replication in Herpes virus (2)?
*By RNA polymerase (in nucleus or cytoplasm of cell)
*each strand of DNA serves as template for its complement (except hepatitis B which synthesizes RNA to act as the template for new DNA)
*ssDNA by RNA polymerase in nucleus of cell using complementary strand of DNA is synthesized to act as template
What is the genome, how is it synthesized, and what molecule is the template for genome replication in Polio virus?
*genome acts as mRNA
*-RNA is synthesized to act as template
What is the genome, how is it synthesized, and what molecule is the template for genome replication in HIV?
*+ssRNA (retroviridae)
*DNA is synthesized from RNA by reverse transcriptase, mRNA is transcribed from DNA by RNA polymerase
What is the genome, how is it synthesized, and what molecule is the template for genome replication in Influenza virus?
*by RNA dependent RNA transcriptase
*+RNA (mRNA)
What is the genome, how is it synthesized, and what molecule is the template for genome replication in Rotavirus?
*Positive stand of genome acts as mRNA
*each strand of genome acts as template for its complement
Describe retrovirus HIV genome.
-genome reverse transcribed by viral RNA-dependent DNA polymerase called 'reverse transcriptase'
-(+ssRNA to DNA to +ssRNA)
Describe the replication of Retrovirus-HIV.
-DNA is integrated into the host cell chromosomes
-DNA is then transcribed by host RNA polymerases to make more +ssRNA
-this +ssRNA then acts as mRNA for synthesis of viral proteins and genome for new viruses
Describe poliovirus genome.
-genome is transcribed by viral RNA-dependent RNA polymerase to make -ssRNA and then more +ssRNA
- (+ssRNA to -ssRNA to +ssRNA)
Describe the replication of poliovirus.
-replication occurs in membrane spherules (genome NOT integrated into host genome in nucleus)
-this +ssRNA (from the -ssRNA from polymerase) then acts as mRNA for synthesis of viral proteins and genome for new viruses
Describe Herpes simplex virus 1's genome.
-genome is replicated by DNA polymerase in nucleus
Describe how Herpes Simplex Virus 1 is replicated.
-DNA transcribed by host RNA polymerases to make mRNA
-mRNA then directs synthesis of viral proteins and capsids are assemble in nucleus
*DNA NOT integegrated into the host cell chromosomes
Describe influeza virus' genome replication.
-genome is replicated by RNA-dependent RNA polymerase (RNA transcriptase) in nucleus
-(-ssRNA to +ssRNA to -ssRNA)
How does the influenza virus replicate?
-the +ssRNA acts as mRNA for synthesis of viral proteins and acts as a template for synthesis of -ssRNA genome for new viruses
Where are most DNA virions assembled and released from?
Where are most RNA virions developed?
-from the nucleus into cytosol
-solely in cytoplasm
What affects the number of viruses produced and released?
-type of virus
-size of virus
-initial health of host cell
*how immune system deals with infection
How are naked viruses released from cell?
-released through lysis and death of host cell
How are enveloped viruses released from cell?
-released by budding; acquires envelope this way
What are the production steps in assembly and release of viruses?
-transcription, translation, intracellular transport, encapsidation of genomic RNA, budding
How much surface area of cell membranes are exchanged each hour?
-50% of surface area
How do viral components travel?
-travel with membranes through the secretory pathway (and out of cell eventually)
What are some potential consequences of integration of viral genome?
-deregulation of nearby cancer genes
-activation of oncogene
-suppression of tumor suppressor gene
What are some consequences of viral infection?
-lysis of "host" cell
-persistent infection
-latent infection
What is latent infection?
-no viral expression for extended time
-can reactivate and lead to cell lysis
-ex: chickenpox, herpes virus
What is cancer in terms of replication?
What percent of cancers are virally induced and give some examples.
-uncontrolled cell division
-mass of neoplastic cells is a tumor
-15%: Burkitts lymphoma, Hodgkins disease, Kaposi's sarcoma, cervical cancer
How does malignancy occur in viral infection?
-tumor cell division (transformation of normal cells to tumor cells)
How does lysis of "host" cell result from viral infection?
-death of cell and release of virus
How does persistent infection work in viral infection?
-slow release of virus without cell death
How does latent infection work in viral infection?
-virus present but not causing harm to cell; later emerges in lytic infection