HIV

• Matrix is a layer of proteins situated under the outer envelope
• Attachment proteins are used by the virus to identify and attach to host cells
• Capsids are a protein layer that encloses two strands of RNA and some enzymes
• RNA contains the genetic material needed to reproduce
• Lipid envelope is not present in all viruses
• Reverse transcriptase is an enzyme that catalyses the production of DNA from RNA
• HIV enters the bloodstream and circulates around the body
• HIV binds to the cell surface membrane protein most frequently found on T helper cells
• Protein capsid fuses with cell surface membrane, RNA and reverse transcriptase enter cell
• Reverse transcriptase catalyses synthesis of DNA from viral RNA
• Viral DNA diffuses through a nuclear pore into the nucleus where it is inserted into the cell's own DNA, remains inactive for a long time
• When the viral DNA becomes active, it produces mRNA using cell enzymes. This contains genetic information for making new viral proteins and RNA to go into new HIV particles
• mRNA diffuses out the cell nucleus through a nuclear pore
• Newly made viral proteins are assembled into new virus particles inside the cytoplasm
• mRNA code provides instructions for cell's protein synthesis mechanisms to manufacture HIV particles
• HIV particles break away from T helper cells with a piece of cell surface membrane, forming the lipid envelope
• What are enzymes?

  Biological catalysts that speed up reactions
• How do enzymes speed up chemical reactions?

  By binding to a substrate at their active site
• What is the role of enzymes in immune function?

  They help in the response to pathogens
• What is the role of enzymes in digestion?

  They help break down food substances
• What are the roles of enzymes in biological processes?

  • Digestion
  • Metabolism
  • Growth and repair
  • Immune function
  • Cell signaling
• What is the role of enzymes in growth and repair?

  They assist in synthesizing new cellular components
• What is the name of the process shown in the image?

  Enzyme catalysis
• What is the specific binding pocket of an enzyme called?

  Active site
• What is the role of enzymes in metabolism?

  They facilitate chemical reactions for energy production
• How does the enzyme facilitate the conversion of substrate into products?

  • Enzyme provides an optimal environment for the reaction
  • Enzyme lowers the activation energy required for the reaction
  • Enzyme brings the substrate and reactants into the correct orientation
  • Enzyme stabilizes the transition state of the reaction
• How does the induced fit model benefit enzyme function?

  It helps the reaction occur more efficiently
• What is the term for the shape change of an enzyme upon substrate binding?

  Induced fit
• How does the induced fit mechanism differ from the lock-and-key model of enzyme-substrate interactions?

  In induced fit, the enzyme changes shape to better fit the substrate, unlike the rigid lock-and-key model
• What happens to the enzyme's shape as the substrate binds to the active site?

  The enzyme changes shape slightly as the substrate binds
• How is the active site of an enzyme related to its specificity?

  The active site is shaped for its substrate
• If the enzyme in the image was changed, how would that affect the induced fit mechanism?

  The induced fit would no longer work as the enzyme and substrate would not fit together properly
• What is the relationship between the enzyme and the substrate in the image?

  The enzyme and substrate fit together like a lock and key
• What is the relationship between enzymes and substrates?

  Enzymes act on specific substrates
• What would happen without enzyme specificity?

  Enzymes would bind to multiple substrates
• What are the main steps shown in the enzyme catalysis process?

  1. Substrate entering the active site of the enzyme
  2. Enzyme-substrate complex formation
  3. Enzyme changes shape slightly as substrate binds
  4. Conversion of substrate into products
  5. Products leaving the active site of the enzyme
• What forms when a substrate enters an enzyme's active site?

  Enzyme-substrate complex
• How does the active site behave according to the induced fit theory?

  It undergoes a temporary conformational change
• What does the induced fit theory describe?

  Enzyme's active site changes shape when binding
• What type of molecule does amylase act on?

  Starch