Life and Germ Theory

Characteristics of Life Living things are organized and have structure Prokaryotes: cell but no nucleus Eukaryotes: cell and nucleus

Characteristics of Life Organisms respond to their environment in order to maintain homeostasis. Exothermic: cannot maintain a constant internal temperature. Endothermic: maintains a constant internal temperature.

Characteristics of Life Organisms use energy for life functions. Producer: makes food from solar energy Consumer: consumes food for energy.

Characteristics of Life Organisms reproduce Asexually: no sex cells involved. Sexually: sex cells involved

Characteristics of Life Organisms grow and develop.

Characteristics of Life Species of organisms evolve to survive in the environment.

Characteristics of Life All organisms are made of cells.

Traditional Cell Theory Robert Hooke First to observe and describe “cells” from looking at cork in a microscope. Anton van Leeuwenhoek Considered the “Father of Microbiology”. He was the first to describe single-celled organisms.

Cell Scientists Matthais Schleiden (1838) Theodore Schwann (1839) Concluded that all plants are made of cells Theodore Schwann (1839) Concluded that all animals are made of cells Rudolf Virchow (1855) Concluded that new cells could only be produced from existing cells.

Traditional Cell Theory Living things are made of cells and cells come from other cells. Cells are the basic unit of structure and function. Cells contain specialized structures to perform life functions.

Additions to the Modern Cell Theory Cells use energy for metabolism and biochemical functions. Cells contain DNA. All cells have the same basic composition in organisms of related species.

Cell Theory

The Source and Treatment of Human Disease Germ Theory The Source and Treatment of Human Disease

What is Disease? Disease is the disruption of the body’s homeostasis by a pathogen (a disease causing agent). This can be caused by: 1. the environment 2. genetics 3. pathogens – organisms that cause sickness

How do Humans Avoid Disease? 1. WASH hands. 2. Eat a healthy diet 3. Get exercise and sleep. 4. Get vaccines (immunizations)

Studying Disease is a Collaborative Effort! The combined work of three different scientists form what modern medicine calls “The Germ Theory”.

Scientist # 1 Louis Pasteur proved that living cells come from other cells. He discovered that many diseases come from microorganisms (germs) that enter the body.

Scientist # 2 Robert Koch used Pasteur's discovery of “germs” and tried to figure out how germs spread from one organism to another.

Scientist # 2 Koch designed a series of experimental steps to isolate and identify the microorganism that was causing the disease. They are called Koch’s Postulates and are still used by the medical community today.

Koch’s Postulates 1. The pathogen is identified in a sick organism. 2. The pathogen is grown in a pure culture. 3. The pathogen is injected into a healthy organism. 4. The healthy organism becomes sick and the pathogen is also found in it.

Scientist # 3 Alexander Fleming is the scientist that accidently discovered penicillin, the first antibiotic. He purified it and found that it would kill bacteria. He saved many lives.

So, what is Germ Theory? It is the idea that disease is caused by a microorganism. 2. Specific rules are followed to isolate and identify the pathogen (microorganism) that causes a disease.

Human Disease How we get sick!

Sources of Disease Diseases can be caused by: Environmental conditions Genetic inheritance And Microorganisms, such as viruses and bacteria.

Environmental Diseases These diseases happen because the body has been exposed to something dangerous in the environment. Examples of environmental diseases include: Many cancers and black lung disease

Genetic Disease Genetic diseases result from the inheritance of detrimental (bad) traits. Examples include: Sickle Cell Anemia and Huntington’s Disease

Infectious Diseases Infectious diseases are illnesses caused by the invasion of a pathogen. These diseases can be passed from one person to another. They may be viral or bacterial.

Viral Diseases Viruses are nonliving and require the human cell in order to reproduce. They cause humans to get sick when they use our cells to reproduce themselves.

Viral Diseases Examples of viral disease include: The common cold The flu And Small Pox

Viral Diseases Viral diseases can’t be cured with antibiotics, but may be prevented with an immunization. Vaccines put a dead virus into the body so the body recognizes and kills any live viruses that enter it.

Bacterial Diseases Bacteria are living cells and grow very quickly; using the body as a habitat and food source. These infections can be treated with antibiotics but some have become resistant to the medications.

Bacterial Diseases Some examples of bacterial infections include: Gum disease Gangrene And Bubonic plague

What are viruses made of? Viruses are made of: A protein coat (capsid) A strand of DNA or RNA Plug/tail fibers

How does a virus make an organism sick? First, the virus attaches to a body cell and injects the DNA or RNA into the cell. Virus Somatic cell

How does a virus make an organism sick? Second, the host cell copies the viral DNA. Making copies of the virus.

How does a virus make an organism sick? Third, the viruses lyse (break open) the cell membrane and leave to infect more cells.

How does a virus make an organism sick? If a virus does this right away, it is called a lytic infection. If the virus remains dormant for awhile, like HIV, it is known as a lysogenic infection.

Virus Infection: NPR http://www.youtube.com/watch?v=Rpj0emEGShQ&feature=related

Are Viruses Alive? In order to be alive, an organism must fit a list of characteristics.

Structure Cells have a cell membrane, organelles, and DNA. Viruses have a protein capsid with a DNA core.

Genetic Code Both cells and viruses have nucleic acid codes.

Growth and Development Viruses do not grow or develop. Cells in multi-celled organisms increase in number and become specialized (differentiate).

Obtain/Use Energy Viruses do NOT obtain and use their own energy. Cells may be autotrophic or heterotrophic.

Respond to the Environment Viruses are NOT able to respond to the environment. Cells are able to respond; moving towards or away from stimuli.

Change over time Viruses mutate; changing over time. Cells also mutate and mix their DNA through reproduction; changing over time.

Reproduction Viruses only reproduce with a host cell; not by themselves. Cells reproduce through sexual or asexual reproduction.

The Ebola Virus – A level 5 virus http://www.youtube.com/watch?v=Us0ovQ1r0Sg&feature=fvw