HIV to AIDS How the disease progresses

Learning OutcomesDiscuss how the evolutionary race between pathogens and their hosts has resulted in sophisticated evasion mechanisms in Human Immunodeficiency Virus (HIV)

Transcription vs TranslationTranscription = synthesis of mRNA from a DNA template

Translation = Ribosomes use mRNA to synthesise new proteins

Sort cards into correct order to remind yourself of protein synthesis

Protein Synthesis (again!)mRNA attaches to ribosomal subunittRNA attaches to mRNA by complementary anticodonRNA polymerase break hydrogen bonds & unzips DNA helixtRNA carries amino acids to ribosomemRNA moves from nucleus to ribosomesRNA nucleotides pair up with complementary DNA bases & form mRNAPeptide bond forms between amino acids

Protein Synthesis (again!)TranscriptionRNA polymerase break hydrogen bonds & unzips DNA helixRNA nucleotides pair up with complementary DNA bases & form mRNAmRNA moves from nucleus to ribosomes

TranslationmRNA attaches to ribosomal subunittRNA carries amino acids to ribosometRNA attaches to mRNA by complementary anticodonPeptide bond forms between amino acids

HIV = Human Immunodeficiency Virus

AIDS = Acquired Immune Deficiency Syndrome

You have 2 minutes....

How is HIV transmitted?

Infection of T helper cellsLymphocyte white blood cells that defend against diseaseT stands for Thymus, the T cells are produced in bone marrow but mature in thymusHelper cells stimulate B cells to divide, are capable of producing antibodies and enhance phagocytosisMacrohpages can also be infected

How HIV worksHIV affects the immune system by invading T helper cells

The cell surface membrane of the virus contains a glycoprotein called gp120 which binds to CD4 receptors on the surface of the host T cell

The viral protein coat then fuses with the host membrane & viral RNA enters that host cellHIV then hijacks the cells DNA transcription process & use it to replicate viral RNA

Reverse TranscriptionThe Virus uses an enzyme called reverse transcriptase to copy viral RNA into viral DNA

Integrase then inserts viral DNA into host DNA which enters the host nucleus

In the nucleus viral DNA produces viral mRNAmRNA triggers the translation of viral proteins in the ribosomes on the RER

These proteins are transported via the Golgi to the cell membrane, where they are incorporated into the host membrane

Viral RNA is produced by the viral DNAThe viral RNA & envelope proteins come together and bud off from the cell membrane to form a new virus

How does this kill the T cell?Once these new viruses have been made they bud off from the T helper cell taking some of the membrane with it

The infected T helper cell still displays some of the viral proteins and is killed by T killer cells

New virus budding from T cell

Label your diagram Some things to remember...Reverse transcriptionIntegraseProtein synthesisViral envelopeViral RNAmRNAViral DNACD4 receptorsBuddinggp120 receptorsIntegrationInfectionReverse transcriptase

Home learningName the enzymes involved in production of viral DNA within the host cell & explain how they workHow is HIV adapted to entering the host cell & taking over protein synthesis?Explain the difference between transcription and translation of proteinsWhich organelles are involved in viral replication and what part do they play?Why does losing T helper cells cause such a problem for the hosts immune system?Define opportunistic infections and explain why these are so dangerous for AIDS sufferers Produce a flow chart to show how the disease progresses from the acute phase to chronic phase to disease phase

BINGO!

TranscriptionDisease phaseDegenerative codeAcute phaseAmino acidsTranslationRNA PolymeraseCodontRNAReverse TranscriptaseT helper cellCondensation reactionCD4 receptorsChronic phasemRNAIntegrase