Biology Lesson #3 PDF

Factors of Illness Lesson 3 What makes us Ill? Are these things living or non-living things? What Makes us Ill? Living or not? ❏ Viruses ❏ NL Viruses ❏ Bacteria ❏ L Bacteria ❏ Chemicals ❏ NL Chemicals ❏ Contaminated ❏ L Contaminated water/air wa...

Factors of Illness Lesson 3 What makes us Ill? Are these things living or non-living things? What Makes us Ill? Living or not? ❏ Viruses ❏ NL Viruses ❏ Bacteria ❏ L Bacteria ❏ Chemicals ❏ NL Chemicals ❏ Contaminated ❏ L Contaminated water/air water/air ❏ Pesticides ❏ NL Pesticides ❏ Mold ❏ L Mold ❏ Pathogens ❏ ??? Pathogens ❏ Diseases ❏ ??? Diseases ❏ Stress ❏ NL Stress  What is a Disease? A disease is an illness which is characterized by specific signs and symptoms Symptoms are evidence of any physical or mental changes caused by the disease. ○ Examples: fever, fatigue, rash, headache What Causes Human Disease? Some causes include: Injury Infection Unhealthy lifestyle Stress DNA Pathogens Pathogens AKA Germs A pathogen (microorganism) is a bacterium, virus or other microbe that has the potential to cause a disease by infecting a host. When the pathogen enters the body, it will multiply and cause infection - a reaction in the body. Some infectious diseases are contagious (or communicable), meaning they are capable of spreading from one person to another. When a pathogen damages the cells to a point of no repair, it is then considered to be an Infectious Disease. What are Microbes? Microbes are any microscopic organism. They include: Bacteria, fungi, protozoa, algae–living cells Viruses– non-living DNA or RNA particles Prions– non-living misfolded proteins that can be infectious (Mad Cow Disease)  Types of Pathogens (and the diseases they can cause) Origin of words: ○ Pathos - “suffering” (ancient Greek) ○ Pathogenesis - “pathos” and “genesis” = creation of disease ○ Pathology – the effects of disease on host such as damage to structure and function, death ○ Pathologist - a person who studies disease  Viruse s Even though there are many factors that can make us physically ill, we will be focusing on viruses and bacteria for the next portion of our unit on the unseen world! Influenza Virus Is a virus a living thing? Why or why not? Viruses are NON-LIVING! They do not display most of the characteristics of living cells Have no membrane bound organelles They do not carry out life processes Their only function is to find a host so that it can reproduce Structure of a Virus All viruses contain nucleic acid (either DNA or RNA) in their core and a protein coat The protein coat (called a capsid) encases the nucleic acid Some viruses have an extra outer envelope which protects the genetic material when travelling between host cells or helps avoid the host’s immune system. On the outside are unique proteins that enable the virus to bind to specific host cells. How are Viruses classified? Based on: Shape DNA or RNA (the nucleic acid) Types of cell they infect Types of diseases they cause Viruses are Host Specific ❏ There is a protein on the surface of the virus which has a shape that matches a molecule on the cell membrane of its host ❏ this allows the virus to lock onto the host cell Some viruses can only replicate in certain types of cells (polio can only enter human nerve and intestinal cells) How do Viruses Replicate? After locking onto the host, the virus injects its DNA or RNA into the host The protein coat remains outside the host Using the host’s metabolism, the viral DNA begins to replicate and form proteins Then, fully formed viruses assemble - Called a virion, it is now the infective form of the virus - free to infect other cells of the body or transmit to a new host How long is someone contagious after a viral infection? Unfortunately, The length of time one is contagious after having a viral infection depends on the type of virus involved. You can often spread the infection to other people before you even start to feel unwell or have noticeable symptoms.  What are Bacteria? Prokaryotic Cells Unicellular organisms that can can form Nuclear region pairs, clusters, colonies or chains Some contain a cell wall Bacteria Facts: Not all bacteria are harmful, some are harmless and even helpful ○ Example: lactobacillus (human digestive tract) They decompose dead plants and animals They convert and recycle essential elements like carbon, oxygen and sulfur Oldest and most abundant living organisms on Earth  Bacterial Reproduction Bacteria reproduce themselves by cell division. Specifically called binary fission. Each time they reproduce, mutations occur that might help them become better adapted to surviving.  Bacterial Growth is Exponential A single bacterium can replicate itself in 20-30 minutes, producing large numbers of identical daughter cells that form a colony; this means millions of cells in a few hours. If there is enough food available their populations increase exponentially. Bacterial infections can spread fast! If you have redness, swelling, or the site of an injury feels hot, get treatment right away. -This species of bacteria doubles y = abx its population size every three hours. -you can recognize exponential growth by the shape of the curve- it starts flat and becomes very steep, almost straight up. How do Viruses and Bacteria make us sick? When a virus invades our cells, our immune system tries to attack it. If our immune system can not work fast enough, the virus will continue to invade more cells. This is the incubation period. Once many cells are killed by the release of the new virus, we become symptomatic and ill. Some viruses remain dormant in your body for decades! (chicken pox, herpes, HIV)  If bacteria are infectious, they will reproduce very quickly in the body. They love warm, moist environments. Many give off toxins that crowd or damage the tissue, and disrupt normal function (or sometimes kill the tissue altogether) Untreated bacterial infections can cause severe or life threatening complications Have you all had this type of infection?  Pathogenic Bacteria are the bacteria that potentially cause harm to the host. ○ Examples include food poisoning, toxic shock syndrome, strep throat, gonorrhea, tetanus and syphilis Zoonotic Diseases Zoonotic diseases are infectious diseases in the animal population that can be spread to humans. ○ Over 60 per cent of infectious diseases that we get are zoonotic while 75% of new, "emerging" infectious diseases are zoonotic. ○ Examples include Rabies, Salmonella, Anthrax, Lyme disease, Ringworm, Ebola, and coronaviruses. Diseases are often species-specific. When conditions are favourable, diseases sometimes can move from one species (such as camels) to another species (such as humans). When a new disease enters the population in this manner it is called a spillover event.  Summary: Bacteria vs Viruses ❏ Viruses are not considered to be ❏ Bacteria are _______________ cells; they are living _______________. __________; they are _____________. ❏ They have _____ membrane-bound ❏ They have _____ cellular structures organelles (such as a ____________, (organelles, cytoplasm, etc.) and mitochondria) but do have ribosomes ________________ carry out life- and cytoplasm where energy is made processes such as producing for growth, reproduction and other life processes. energy, growing and reproducing. ❏ They have a _______________. ❏ They have an outer protective coat ❏ They are ____________ celled; reproduce called a ___________ by __________________ to form a ❏ They are ______________ units. collection of identical _____________ cells ❏ _______ are harmful, but some are called colonies. helpful (_________________ are ❏ Many are _______________ but some are harmful. helpful, the rest, not)  Summary: Bacteria vs Viruses Bacteria Viruses Bacteria are prokaryotic cells; they Viruses are not considered to be are living organisms. They have no membrane-bound cells; they are non-living. organelles (such as a nucleus, They have no cellular structures mitochondria) but do have ribosomes (organelles, cytoplasm, etc.) and and cytoplasm where energy is made cannot carry out life-processes for growth, reproduction and other life process. such as producing energy, They have a cell wall. growing and reproducing. They are single celled; reproduce by They have an outer protein coat binary fission to form of a collection of called a capsid identical daughter cells called colonies. They are single units. Many are helpful and some are Most are harmful, but some are harmful. helpful. The exception is a Bugs and Drugs: Bacteria, Viruses, and Medications Read pages 12-13 in Pandemic book. In pairs or small groups, discuss the following questions: Why is it important to know the causes of an illness? How does your body fight infections? How do antibiotics work to fight infections? Do they work on viruses and bacteria? How can individuals develop a resistance to antibiotics? What is a vaccine? How do vaccines work? Why do some viruses only infect you once while others can infect you multiple times?