Compare the structures and functions of viruses to cells
Todays Objective: Compare the structures and functions of viruses to cells Viruses Doesnt belong to any kingdom -Its not a plant or an animal.
-Its not a fungi, protist, orbacteria. WHAT IS A VIRUS? A virus is an infectious agent made up of nucleic acid (DNA or RNA) wrapped in a protein coat called a capsid. Viruses have no nucleus, no organelles, no cytoplasm or cell membraneNon-cellular This is why it does NOT belong to any kingdom. vs Viruses with RNA that transcribe into DNA are called retroviruses.
Viruses have either DNA or RNA but NOT both. Viruses with RNAthat transcribe into DNA are called retroviruses. Viruses are parasitesan organism that depends entirely upon another living organism (a host) for its existence in such a way that it harms that organism. HIV Infected Cell (This is the reason why HIV is so incurable.) A flea is a parasite to a dog and is harmful to the dog. Section 18.1 Summary pages 475-483
Viruses are extremely small non-living particles composed of genetic material (DNA or RNA) enclosed in a protein coat. They are smaller than the smallest bacteria. Bacteriophage Viruses Flu Viruses Section 18.1 Summary pages Section 18.1 Summary pages 475-483
What is a Virus? Viruses are considered NON-LIVING because: They cannot metabolize food for energy They are NOT cells All viruses can do is replicatemake copies of themselveswith the help of living cellsa HOST CELL. Section 18.1 Summary pages Bacteriophageviruses that infect bacteria
Capsid (protein coat) inside contains either RNA or DNA 2. Flu (influenza), HIV DNA or RNA SurfaceMarker D. Replication is how a virus spreads.
A virus CANNOT reproduce by itselfit must invade a host cell and take over the cell activities, eventually causing destruction of the cell and killing it. (The virus enters a cell, makes copies of itself and causes the cell to burst releasing more viruses.) DNA/RNA iscopied. DNA/RNA injectedinto cell. Virus attachesto cell. Step 3 Step 2 Step 1 Virus copiesitself. Cell bursts (lyses) andreleases new viruses. Step 4 Step 5 Some viruses hit you fast
The lytic cycle is a viral replication cycle in which a virus: 1.takes over a host cells DNA 2.uses the host cells structures and energy to replicate the virus 3. then the host cell bursts(lyses), dies, and releases the replicated viruses. Some viruses slowly sneak up on you
A lysongenic cycle begins in the same way as a lytic cycle. However, in a lysogenic cycle, instead of immediately taking over the hosts genetic material, the viral DNA is integrated into the host cells chromosome. Section 18.1 Summary pages 475-483
The Lysogenic Cycle Viral DNA that is integrated into the host cells chromosomes is called a provirus. Every time the host cell reproduces, the provirus is replicated along with the host cells chromosome. This can go on for years Section 18.1 Summary pages Section 18.1 Summary pages 475-483
Once the virus is ready to take over other cells. Lysis, the bursting of a cellResult: Cell Death Section 18.1 Summary pages In the lytic cycle, the virus reproduces itself using the host cell's chemical machinery. In the lysogenic cycle, the virus reproduces by first injecting its genetic material, integrating its DNA into that of the cells. Certain viruses can only attack certain cell types
Certain viruses can only attack certain cell types. They are said to be specific. Example: The rabies virus only attacks brain or nervous cells. Surface Markers Virus Receptor Sites Its like the pieces of a puzzle. The ends have to match up so only certain pieces fit. Cell A virus recognizes cells it can infect by matching its surface marker with a receptor site on a cell. Virus Surface Markers Cell Receptor Sites Importance: Beneficial: *Harmful Causes diseasepathogenic
Disease producing agentpathogen Human Diseases: Warts, common cold, Influenza (flu), Smallpox, Ebola, Herpes, AIDS, Chicken pox, Rabies Viruses disrupt the bodys normal equilibrium/balance Viruses can be prevented with vaccines, but NOT treated with antibiotics. (antibiotics treat bacteria) Beneficial: Genetic Engineeringharmlessvirus carries good genes into cells. Virus Living Cell RNA or DNA core (center), protein coat (capsid)
Cell membrane, cytoplasm, genetic material, organelles Structure Copies itself only inside host cell--REPLICATION Asexual or Sexual Reproduction DNA and RNA Genetic Material DNA or RNA Growth and Development NO YESMulticellular Organisms Obtain and Use Energy NO YES Response to Environment YES NO Change over time NO YES Are viruses living? NO ONE
How many characteristics of life do viruses possess? ONE *Genetic Material Are viruses living? NO A cell in which a virus replicates inside of is called the host cell.