Viruses

Virus A tiny particle that contains nucleic acid encased in protein Nucleic acids – organic compounds that contain genetic information and the information necessary for an organism to make the protein it needs

Viruses Viruses are much smaller than the tiniest cell Viruses were discovered with the invention of the electron microscope. (uses a beam of electrons instead of light to detect objects)

Virus shapes Sphere shaped Rod shaped

Virus Shapes Spiral shaped Thread shaped

Are viruses living things? We don’t know. VIRUSES: can reproduce (by infecting a living cell) and mutate (living thing) contain proteins that are found only in living things (living thing) have genetic material (living thing) are not made of cells (non-living) cannot mutate or reproduce outside a host (non-living) genetic material resembles host more than virus (non-living)

Virus Reproduction Computer virus is what??? Piece of software designed to secretly enter system and infect files Think of a virus as a genetic program wanting to reproduce, but it must be in a host cell Viral infection – the penetration of a virus or its nucleic acid into a host cell. Without a host there is NO virus reproduction

Virus Reproduction Infection can begin in several ways Bacteriophage- (virus that infects bacteria) Animals – virus enters host cell Plants – virus enters a wound in the plant Retrovirus – virus that carries genetic material Ex. HIV causes AIDS (hides in cell; deadly effect)

BASIC PATTERN of Viral Reproduction virus gets itself or its genetic material into host cell host cell makes more virus particles virus particles leave the host cell to infect more cells.

Bacteria Bacteria – one celled organisms without a nucleus Bacteriologists and microbiologists believe most species of bacteria are undiscovered. Bacteria can only be seen under a microscope.

Parts of Bacterium Cell wall – determines the shape of a bacterium Capsule – slimy layer outside the cell, protects the cell from destructive chemicals Cell membrane – allows small food particles to pass through Cytoplasm – contains enzymes that help break down food and build cell parts Hereditary material – moves freely around the cell Flagellum – thin, whip like structures that help an organism move through liquids

Shapes of Bacteria round shaped – cocci rod shaped –bacilli spiral shaped – spirilla bent rods – vibrios Descriptive prefixes Diplo – pair Staohylo – cluster Strepto – chain Streptococci = round bacteria linked in chains

Bacteria Life Functions All bacteria reproduce asexually (reproduction that involves only one parent and in which the offspring is identical to the parent) Binary fission – is cell division in which one cells splits into two identical daughter cells, each having a complete set of DNA Budding – asexual reproduction in which a small part of the parent develops into an independent organism Aerobic (“with oxygen”) bacteria need oxygen to live, but anaerobic (“without oxygen”) bacteria do not

When bacteria find themselves in conditions that might harm them, they take action. Bacteria form endospores (protective capsules that protect them from extreme heat or drying out. Allow bacteria to remain dormant (resting state)

Autotrophs – organisms that make their own food from simple substances Use sunlight and water to produce energy through photosynthesis Heterotrophs – organisms that can’t make their own food Feed on other living things, causing infections is plants, animals and people. These are the bacteria that make us sick Decomposers – organisms that get their energy by breaking down the remains of the dead organisms or animal wastes Help dead organisms from piling up