Chapter 18

As a group discuss for 1 minute. Be able to defend your answer for the class!

Growth and Development Reproduce Change Over Time Obtain and Use Energy Maintain Homeostasis Composed of Cells Respond to the Environment Contain Genetic Material

Non-living  Virus: Non-living, parasitic, biological particle. cancer  All viruses cause some sort of disease. Some even cause cancer.

reproduce  They can not reproduce outside a “host” cell cellular respiration  They do not carry out cellular respiration  They do not growdevelop  They do not grow or develop

 Nucleic Acids  DNARNA  DNA or RNA Core  Holds the genetic material that will affect the host  Proteins Capsid enter  An outer protein coat called a Capsid enables the virus to enter certain cells.

 Glycoproteins  Projections that help the virus attach to host  Not all viruses have glycoproteins.

smaller cell Viruses are smaller than the smallest cell

 Host:  Host: a cell in which a virus replicates  Host Specific single  Host Specific: most viruses or bacteria will only affect a single host or a small group of host species Examples: birds people  West Nile Virus – affects birds, horses, and people  Influenza peopl  Influenza type B – affects only people not others dogs  Parvo – affects only dogs, not other organisms

bacteriophage  Viruses that attack bacteria are called bacteriophage or just phage  T-phages  T-phages are a specific class of bacteriophages with icosahedral heads, double- stranded DNA, and tails

T4 T7  The most commonly studied T-phages are T4 and T7 E. coli bacteria  They infect E. coli, an intestinal bacteria attach  Six small spikes at the base of a contractile tail are used to attach to the host cell  Inject viral DNA into cell

 Once the viral genes get inside a cell, the genes are expressed.  This genetic program causes the host cell to make copies of the virus.  In the process, the host cell is destroyed.

two  There are two ways this can occur Lytic 1. The Lytic Cycle Lysogenic 2. The Lysogenic Cycle

STEPS 1. Attach Virus “docks” with host cell 2. Injection Virus inject it’s DNA/RNA into host cell 3. Replicate replication of virus parts 4. Lysis cell ruptures and new virus’ invade tissues of the host to break or rupture cells or cell membranes Lysis – to break or rupture cells or cell membranes

STEPS 1. Attach Virus “docks” with host cell 2. Injection Virus inject it’s DNA/RNA into host cell 3. Incorporate DNA attaches to the cells own DNA 4. Time Goes By 5. Stress 6. Replicate replication of virus parts 7. Lysis cell ruptures and new virus’ invade tissues of the host

Common Cold 1. Common Cold  How do we catch it? Contact with contaminated objects; droplet inhalation  What are the symptoms? Sneezing, Sore Throat, Fever, Headache, Muscle Aches

Influenza 2. Influenza  How do we catch it? Contact with contaminated objects, droplet inhalation.  What are the symptoms? Body Aches, Fever, Sore Throat, Nasal Congestion, Headache, Dry Cough, Fatigue.

Ebola 3. Ebola  How do we catch it? exposure to blood or bodily secretions of an infected person, or through direct contact with the person.  What are the symptoms? Sore Throat, Fever, Dry hacking cough, Weakness, Severe Headache, Joint and muscle aches, Diarrhea, Dehydration, Stomach pain, vomiting, Internal and external bleeding.

Herpes Viruses 1. Herpes Viruses  Once a person is infected with a herpes virus they are infected for life.  Examples: Chicken Pox Shingles Chicken Pox can reappear later in life as Shingles HSV-1 (oral herpes) and HSV-2 ( genital herpes)

2. HIV  How do we catch it? Contact with contaminated blood or bodily fluids  What are the symptoms ? T cells (needed for normal immune function) are destroyed

RNA  Retroviruses are viruses that contain RNA as their genetic information backwardRNA cDNA  Retroviruses get their name from the fact that their genetic information is copied backward, from RNA to cDNA.  HIV  HIV is the most infamous retrovirus

ANTIBIOTICS ANTIBIOTICS DO NOTHING FOR VIRAL INFECTIONS!!! Immune system  After enough cell debris (from blown up cells) is detected your Immune system gets involved  Macrophages  Macrophages are large white blood cells that get rid of debris by eating it.  When they eat too much, they die. These dead cells and the cell debris are “puss”

Lymph nodes  Other white blood cells pick up viral particles from the battle and carry it to Lymph nodes.  In the lymph nodes, they look for cells to fight this type of virus.  T- cells  T- cells (thyroid cells) are called upon and go to the site of the infection to kill specific infected cells  B-cells antibodies  B-cells (bursal cells) make antibodies that go to the site and kill free viruses

prevention vaccines  The best way to protect against most viral diseases lies in prevention, often by the use of vaccines. before  Most vaccines provide protection only if they are used before an infection begins.