VIRUSES Chapter 24 Video VIRAL STRUCTURE AND REPLICATION
- Slides: 30
VIRUSES Chapter 24 Video
VIRAL STRUCTURE AND REPLICATION Section 24. 1
Discovering Viruses: n Late 1800’s – Something very small is causing diseases! n 1935 – It is not made of cells (living things). TMV Polio HIV
What is a virus? n. A nonliving particle composed of a nucleic acid and a protein coat. n Study of viruses = virology
Why do we study them? n Cause disease in living organisms n Useful tools for genetic research
Are viruses living? The Characteristic of life: growth homeostasis metabolism organization cells reproduction n Viral characteristics: NO NO NO YES NO within host cell
Common Diseases Caused by Viruses n AIDS n Influenza n Chickenpox n Rabies n Polio n Mumps n Colds
Viral Structure n n All viruses have: 1. Nucleic acid: (DNA or RNA) 2. Capsid: protein coat Some viruses have: 1. Glycoprotein projections: signals 2. Envelope: Bilipid membrane surrounding the capsid. § Can fit “lock-and-key” with receptors on host cell.
HIV
Grouping viruses based upon… SHAPE AND STRUCTURE: n Envelope present or not? n DNA or RNA? n Single stranded or double stranded? n How does it affect a human? Rabies Hepatitus Herpes
Viral Size & Shape n Size: – 20 to 250 nm – Cannot be seen by a light microscope n Shape: – Determined by the genome (DNA/RNA) or capsid (protein)
Some shapes: H 1 N 1 or influenza Video
Viral Replication: Obligate Intracellular Parasites (huh? )
Viral Replication in Eukaryotes n DNA viruses: – DNA m. RNA proteins – Provirus: inserted viral DNA into host cell n RNA viruses: – m. RNA protein n Retroviruses: – RNA DNA m. RNA protein – Reverse transcriptase: enzyme – Example: HIV Video
Viral Replication in Prokaryotes n Bacteriophage: virus that infects bacteria n Helped scientists discover how viruses replicated n Two replication cycles – Lytic cycle: virulent – Lysogenic cycle: temperate
L Y T I C C Y C L E Animation
L Y S O G E N I C C Y C L E Animation
Origin of Viruses n Early viruses evolved from early cells n Viruses mutate quickly and frequently – Thus they evolve quickly – New strains formed this way
Viral Disease Section 24. 2 Flu Video
Vectors n An intermediate host that transfers pathogens from one organism to another n Examples: – – – Humans Animals mosquitoes Fleas ticks
Chicken Pox & Shingles n Virus: varicella-zoster herpesvirus n Symptoms: rash & fever n Replication: Multiplies in lungs and uses blood network to reach skin n Transmission: direct contact with skin rash
Viral Hepatitis n Virus: Hepatitis A, B, C, D, E n Symptoms: – Fever, nausea, jaundice, liver failure n Transmission: – Sexual contact (B, C, D) – Fecal matter in food & water (A, E)
AIDS n Virus: HIV – retrovirus Transmission: through bodily tissues and fluids n Symptoms: weakened immune system n n Treatment: Drugs target reverse transcriptase OR stop new capsids from forming (protease inhibitors).
Viruses and Cancer n Cancer: when cells divide at an uncontrolled rate and form a tumor n Oncogenes: viral genes that cause cancer n Examples: – HPV cervical cancer – Hepatitis B liver cancer – Epstein-barr lymphoma
Emerging Viruses n New viruses are being discovered every year as humans alter ecosystems n Examples: – – HIV Ebola SARS West Nile
Preventions and Treatments 1. Vaccinations: to prevent disease – Inactivated or attenuated – Smallpox eradication 2. Vector Control: n Wildlife population control 3. Drug Therapy: n Interfere with viral nucleic acid
How to protect yourself and others… 1. Wash your hands! 2. Don’t share tools (cups, toothbrushes) 3. Use protection when transmitting bodily fluids 4. Don’t become someone’s “Blood brother” 5. Avoid being bitten by animal 6. Cover your mouth when sneezing
Non-virus Disease Causers: Viroids – a short singular strand of RNA § smallest known particle to cause disease § infects mostly plants Prions - protein particles without a genome § mad cow disease
Practice Graphing Problem
- Section 24-1 viral structure and replication
- Unlike lytic viruses, lysogenic viruses do not
- Youtube . com / watch v = roxnvcaezjs
- Replication of viruses
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- Bioflix activity dna replication dna replication diagram
- Chapter 21 viruses and bacteria
- Chapter 20 viruses and prokaryotes
- Chapter 7 lesson 1 what are bacteria answer key
- Chapter 20 viruses and prokaryotes
- Study guide chapter 18 section 1 bacteria
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- Dna structure and replication packet answer key
- Nature of dna replication
- Section 19-3 diseases caused by bacteria and viruses
- Section 1 studying viruses and prokaryotes
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- Vrus
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- Viral inoculation in embryonated egg
- Viral inoculation in embryonated egg
- Virus cultivation in embryonated eggs
- Spasmodic croup
- Variola varicela
- Morfologia viral
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- Tratamiento meningitis viral
- Causes of viral hemorrhagic fever
- Inmunidad
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- Viral