Life Science—chapter 2 Viruses Microscopes Cells

Viruses Definition – --virus is a piece of hereditary material covered by a protein coat that infects and reproduces only inside a living cell.

Viruses Characteristics – Very small – Can make a crystal structure – Need a host cell to reproduce – Classified by Shape Hereditary material (DNA or RNA) Kinds of organisms they infect Method of reproduction

Viruses Reproduction type one – Active Virus See page 34 in text book –Steps Attach Invade Copy Release –Become active right away and cause disease or other

Viruses Reproduction type two – Latent Virus See page 35 Steps –Enters a cell and becomes part of the cell’s DNA and hides until something triggers it to react –Then follows same steps as active

Vaccine Definition – vaccine is made from damaged virus particles that can’t cause disease anymore, help build immunity for the virus so that when you get the strong form of the virus, it can be killed quickly

Diseases Caused by Viruses List

AIDS Define – Acquired Immune Deficiency Syndrome – Caused by HIV Human immunodeficiency virus – Allows the body to be infected by many organisms that cause disease

Microscope Parts – Page 41 in text book

Microscope Parts cont. – Has one or more lenses – Enlarges objects – Compound microscopes – Stereomicroscopes – Anton Van Leeuwenhoek Developed first microscope

Compound Light Microscope Lets light pass through an object then through two or more lenses Lenses enlarge the image and bend light toward your eye

Stereomicroscope Gives 3-D view of object Ocular for each eye Doesn’t enlarge image as much as compound light microscope

Electron Microscope Uses a magnetic field to bend beams of electrons Magnify up to 1,000,000 times TEM—transmission electron microscope – Used to study parts inside a cell – Vacuum sealed – Very thin slice of the specimen needed SEM—scanning electron microscope – Used to see the surfaces of whole objects

Cell Theory-Scientists Hooke first to see cells Schleiden – concluded that all plants were made of cells Schwann – concluded that all animals were made of cells Virchow – cells divide to form new cells

Cell Theory States All organisms are made up of one or more cells Cells are the basic units of structure and function in all organisms All cells come from cells that already exist

Types of Cells—1 st Type Prokaryotic Cells – No membrane around their nuclear material – Bacteria – No membrane bound organelles—like golgi bodies, endoplasmic reticulum, mitochondria, chloroplasts etc.

Types of Cells—2 nd Type Eukaryotic Cells – Has a nucleus with a membrane around it – Has membrane bound organelles – Animal, plant, protists, fungi

Animal Cells See figure 2-14 on page 46 – Use tables of organelles and functions

Plant Cells See figure 2-19 on page 51 – Use tables of organelles and functions

Cells Cells vary in size and function Cells Tissues—a group of cells Organs—a group of tissues Organ systems—a group of organs Name some organ systems Cells—tissues—organs— organ systems