Viruses, Health and Disease - Biology - Lecture Slides, Slides of Biology

Download Viruses, Health and Disease - Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! Viruses Docsity.com Is a Virus a Living Organism? Chapter 1 – Properties of life – Cellular Respiration – Reproduction – Metabolism – Homeostasis – Heredity – Responsiveness – Growth and development Docsity.com RNA or DNA? Viruses with RNA – Human immunodeficiency virus (HIV) – Influenza viruses – Rabies Viruses with DNA – Warts – Chickenpox – mononucleosis Docsity.com Virus Shapes Helical Rodlike with capsid proteins winding around the core in a spiral Tobacco Mosaic Virus Docsity.com Virus Shapes Polyhedral Has many sides Most polyhedral capsids have 20 sides and 12 corners Docsity.com In the lytic cycle, the virus reproduces itself using the host cell's chemical machinery. The red spiral lines in the drawing indicate the virus's genetic material. The orange portion is the outer shell that protects it. Docsity.com In the lysogenic cycle, the virus reproduces by first injecting its genetic material, indicated by the red line, into the host cell's genetic instructions. Docsity.com Viruses Enter Living Cells Viruses enter bacterial cells by punching a hole in the cells wall and injecting its DNA Docsity.com Viruses are host cell specific. Most viruses are restricted to certain kinds of cells (those that infect plants cannot infect animal cells). Why? Scientists think that viruses originated from escaped genetic material from host cells. Docsity.com Viruses can be beneficial… Bacteriophages – attack & destroy bacteria Baculovirus – ebola-like virus that attacks insects – Could use for pest control in crops • Cabbage loopers eat cabbage crops • Virus can kill pests in days – (it’s really gross) … and then there are those that are not so good…. Docsity.com Also important… Any agent (not just viruses) that causes disease is a pathogen. When a virus inserts its genetic material into a host’s DNA, it is called a provirus. Some viruses replicate very slowly and only cause damage when the conditions are “right”. (cold sores) Docsity.com HIV Making Factories • Virus enters cell through endocytosis • Virus replicates RNA to DNA with reverse transcriptase Docsity.com • DNA enters nucleus & binds with host DNA • New virions exit cell through exocytosis to infect other cells (notice cell isn’t destroyed) •mRNA is created (carries instructions for making new viral proteins) and leaves nucleus •Uses host cell’s enzymes to make new viruses Docsity.com How Is HIV Spread? • Sexual contact • Sharing contaminated needles • Blood transfusions • Breast feeding (mother to baby) • Mother to baby during pregnancy or birth Docsity.com