Enzymes and Prions Quiz

• Microbiology for Nursing and Allied Health, BIO 185, Lecture 4 by Dr. Marjan Sharifi

Lytic and Lysogenic Pathways

• After entering a host cell, a virus genome may orchestrate one of two events.
• Viruses must decide between the lytic and lysogenic cycles in every infection, or whether to lysogenize and keep the host viable.
• Certain viruses can reproduce via the lytic and lysogenic cycles.

Lytic Pathway

• A virus replicates and destroys its host cell.
• They replicate inside and lyse their host.
• In a lytic infection, the virus redirects the host cell's metabolism from growth to support virus multiplication and new virion assembly.
• Newly-formed virions are released as the process repeats itself in new host cells.
• The Ebola virus undergoes the lytic cycle.

Lytic Replication of Bacteriophage

• Animal virus replication was learned by studying bacteriophages.
• Cell lysis releases new phages.
• No envelope is present.

Lysogenic pathway

• Some viruses can result in a lysogenic infection.
• The host cell is not destroyed, and the viral genome becomes a component of the host genome.
• The herpes simplex virus and human immunodeficiency virus (HIV) follow lysogenic pathways.

Lysogenic Replication of Bacteriophage

• Viruses can sometimes cause lysogenic replication.
• Favorable conditions trigger lysogenic replication.
• The genome integrates into the host as a provirus (like HIV).
• This replication is silent.
• Bad conditions trigger the lytic cycle, producing millions of viruses.

Viral Replication

• During the Lysogenic Cycle, Viral DNA does not assume control of the cell.
• Viral DNA inserts into the host's DNA.
• Nucleic acid is integrated for generations
• The host cell acquires new genetic information
• Animal viruses and bacterial viruses are basically the same as bacteriophages.
• Latency is similar to lysogeny.

Mechanisms of Virus Entry

• Direct penetration: poliovirus
• Membrane fusion: measles virus and HIV
• Endocytosis: non-enveloped adenovirus or enveloped herpesvirus

Synthesis of New Animal DNA Virus Genomes & Proteins

• Genomes look similar in animal DNA viruses.
• Genomes are replicated by cell DNA polymerase (nucleus).
• Host RNA polymerase transcribes DNA into RNA (nucleus), which ribosomes translate into proteins (cytoplasm).

Synthesis of New Animal RNA Virus Genomes & Proteins

• Genomes do not resemble animal RNA virus genomes because the virus requires a special viral enzyme.
• The viral RNA polymerase replicates the genome (cytoplasm).
• Ribosomes translate RNA into proteins (cytoplasm).

Assembly of New Viral Genomes and Proteins in Eukaryotes

• Pay attention to where the majority of DNA and RNA are detected.
• DNA viruses are located in the nucleus.
• RNA viruses are located in the cytoplasm.

Release of Newly Assembled Viruses

• Non-enveloped viruses release through Lysis - plasma membrane ruptures or Exocytosis - vesicle with virus inside fuses with plasma membrane
• Enveloped viruses releases through Budding

Viral Diseases

• Examples of include Measles, Mumps, Chickenpox, Shingles, Influenza, Common Cold.

Viruses Role in Cancer

• Viruses induce 15% of human cancers.
• Burkitt's lymphoma and Hodgkin's disease are caused by Epstein-Barr Virus.
• Kaposi's sarcoma is caused by Herpes 8 Virus.
• Cervical cancer is caused by Human Papilloma Virus.

DNA Tumor Viruses

• Some DNA animal viruses can cause tumors by catalyzing lytic events, or integrating into a genome in a latent state.
• Included are viruses of the polyomavirus family, as well as some herpesviruses having double-stranded DNA genomes

Herpesviruses

• Herpesviruses compose a large group of double-stranded DNA viruses, causing diseases like fever blisters (cold sores), chicken pox, shingles, and infectious mononucleosis.
• Certain herpesviruses can cause cancer.
• Herpesviruses can remain dormant for extended periods of time.
• They become active when stress or immune deficiencies exist.
• Herpesvirus virions are enveloped and possess structural layers over the icosahedral nucleocapsid.
• Host cytoplasmic membrane fuses with the virus envelope following viral attachment which release the nucleocapsid cell , transporting Viral DNA that is uncoated and produced into mRNA to the nucleus

Viruses - Cultivation

• Viruses can be cultivated using lawns of bacteria, live animals or plants, embryonated eggs, or cell cultures (tissues) such as HeLa.

Subviral Agents

• Some noncellular microbes are more streamlined than viruses and lack either protein or nucleic acids.
• Viroids and prions represent two such subviral agents.
• These agents resemble viruses but lack nucleic acid (prions) or protein (viroids).

Viroids

• Viroids are infectious RNA molecules devoid of a protein component.
• They are small, circular, single-stranded RNA molecules and the smallest known pathogens.
• Number of crucial plant diseases are attributed to Viroids impacting agricultural
• No viroids have infected animals, or microorganisms

Prions

• Prions represent the side from that of viroids.
• Prions consist entirely of protein as infectious agents.
• Prions lack both DNA and RNA.
• Prions are responsible for various neurological diseases in animals.
• Amyloids plus transmissible spongiform encephalopathies correlate with
• Debilitating human disease, like type 2 diabetes Alzheimer’s, Huntington’s and Parkinsons

Prion

• Misfolded normal cellular protein occurs in the brain cell
• Prions cause fetal diseases like spongiform encephalopathies
• Scrapie (sheep)
• Mad cow disease (cow)
• Kuru (New Guinea cannibals)
• Creutzfeldt-Jakob disease (spontaneous in humans)
• Spontaneous/transmitted
• Occurs through ingestion, transplantation, contact with mucous membranes with infected nervous tissue
• Destroyed by incineration/ autoclaving in concentrated sodium hydroxide
• With no Cure, incubation is from 5-40 years and lasts 12-14 months

Prion Disease

• Normal protein converts to misfolded form is prion affects brain cells
• Build up of prions is fatal to neurons
• Vacuoles, plaques from death of individual

The Role of ATP in Metabolism

• Metabolism represents chemical reactions in organisms.
• Catabolism makes ATP.
• Anabolism consumes ATP.

Metabolism

• Metabolism equals a grouping of actions
• Catabolism is energy realizing, reactions that are Exergonic.
• Simpler substances result from complex organic compound
• There is a degradation of reactions that includes Hydrolytic reaction, Chemical Bond are destroyed
• Anabolism represents energy consuming a reaction and are endergonic
• Simpler organic compounds are more complex, and involves Anabolic and biosynthetic reactions, and Dehydration synthesis reactions

How Do Chemical Reactions Occur?

• Continually moving Atoms, Ions Molecules collision
• Disruption of electrons breaks and from bonds through energy that collides’
• Electrons are disrupted and broken. Activation energy is required.
• Reaction rate is how frequent the collision
• Temperature/Pressure Increases with enzymes.

Enzymes

• Regarding reactions, temperatures and Physiological pressure is minimum for reactions, in order to accelerate
• Activation of energy, can be accelerated with lower enzymes -Reactants are brought nearer, -Reactants Orient Enymes increase reaction by straining reactant

Enzyme Structure

• There are two structures of Enzyme and those include Enzymes- Simple and Enzymes are Conjugated or known as holoezymes
• Simple enzymes or protein.

Enzymes Structure

• Composed of 1)Protein part called Apoenzyme. 2) non-protein parts called Cofactor with both being a Functional unit.
• cofactor-InOrganic and Ions • Specific substrate binds the active site,

Haloenzyme

• Haloenzyme has
• Aprotein and part known as apoenzyme and a cofactor a nonprotein part as well as a substrate

How do Enzymes work?

• Enzymes turn lower and weaken bond to the lower and activation of the energy
• Enzymes have a surface that is there dimensional- complex which they fit particular reactant as a clove on there hand.
• Enzymes shape is induced slightly and it finds to form the enzymatic subtract complex
• Reaction is brought together by enzyme with the resulting atoms of the closer bonds.

THE FINAL STRUCTURE OF AN ENZYME CAN INFLUENCE ITS FUNCTION.

• Structure shapes the final stage of the enzyme

Enzymes and Chemical Reactions

• The lowering of activation by enzymes (speed up) Catalyze to specific.
• Each have different substrate, however they don’t change

Mechanism of Enzyme Action.

• Activation energy and Enzymes are specific.
• Enzyme is still attached;
• In optima position-

Enzymes

• The lock and key model has global protiens and the Enzymes are specific reactions

Factors that can Influence Enzyme Activity.

• Rise substrate will rate to a point
• Maximum velocity (Vmax)
• Rise Substrates increase at which point
  • Enzymes at (Vmax) that fully
  • Increase and add any enzymes

-At low temp protiens don’t have the ability to freeze, instead they’re low-Functional

• Influence of enzyme activity

Regulation of Enzyme Function.

• Environmental and temperature function

1. conditions 2)Shape is been determined over site on activities

Enzymes

• Enzyme can denatures and and denatured that functions as functional inhibition over chemical bonds. • Can Inhibit and has competitor as competitive and an allosteric (Non-competitive)

Factors that can Influence Enzyme Activity

• As one enzyme goes away, competitor inhibits and that is known over time
• Sulfanilamide (Sulfa drug)
• PABA Conversion and to folic acid needed for growth
• Competitive will result in point and allosteric.

Factors that can Influence Enzyme Activity

• Factors Shape ( Binds allosteric) but it wont act as a competitor Feedback

Test your knowledge of enzymes and prions. This quiz covers enzyme function, specificity, and the induced fit model. It also explores the characteristics, transmission risks, and unique features of prions versus typical pathogens.