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Biology : The Study Of Life

Explore the 8 characteristics that define life and learn about the debate on whether viruses are considered alive. Discover how viruses affect our health and their relationship to cancer.

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Biology : The Study Of Life

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  1. Biology:The Study Of Life

  2. Biologists have devised a list of 8 characteristics that define life. • Something can be considered alive ONLY if it displays ALL 8 of the characteristics. • Anything that possesses all 8 of the characteristics of life is called an organism. The Characteristics of Life

  3. 1. Displays cellularorganization: • Cell = the basic unit of structure and function in all living things. • Smallest unit that can perform all life’s processes. • Living things are made of one cell (unicellular) or many cells (multicellular). The Characteristics of Life

  4. The Characteristics of Life • For complex multicellular organisms, cells specialize. • Levels of Organization: -Cells form tissues -Tissues form organs -Organs form organsystems

  5. The Characteristics of Life 2. Responds to stimuli They are able to react, or respond, to an environmental condition, or stimulus. Discuss an example with a partner…get ready to share your ideas! Venusflytrap

  6. 3. Maintains homeostasis: The Characteristics of Life • All organisms are able to maintain a relatively constant internal environment. • Homeostasis: The regulation of an organism’s internal environment to maintain conditions suitable for life. • Example – maintaining a constant body temperature – sweating

  7. The Characteristics of Life 4. Metabolism • Organisms require energy to perform life processes such as repair, movement, and growth. • Metabolism = the sum of all the chemical reactions that take in and transform energy and materials from the environment. • Discuss (with a different partner) how different types of organisms might obtain their energy

  8. 5. Grow and Develop: • All living organisms grow and develop during their life spans. Growth: An increase in the size of an organism due to an increase in the size and number of cells Development: All of the changes that take place throughout the life span of an organism The Characteristics of Life

  9. 6. Reproduction: • All organisms produceoffspring • Although reproduction is not essential to the survival of an individual organism, it is essential for the continuation of a species. The Characteristics of Life

  10. 7. Contain geneticinformation that can be passed on through generations: • Hereditary information is transmitted through a molecule called DNA. • Gene: Segment of DNA that contains instructions for a specific physical trait. The Characteristics of Life

  11. The Characteristics of Life 8. Evolve Over Time • Individual organisms do not evolve • However, populations of living things do change over time (evolve). • Ability to evolve is essential for survival in a changing world.

  12. VIRUSES

  13. Viruses: Alive? Yes or No? Discuss! Which of the 8 characteristics do they have? https://www.youtube.com/watch?v=Q0vqi0vv_Fc

  14. Viral Structure

  15. Well-Known Viruses • Hepatitis A, B, and C viruses • Rabies virus • Varicella(causes chickenpox and shingles) • Norovirus (causes gastroenteritis) • Rotavirus (causes gastroenteritis) • Poliovirus • Herpes virus (many different strains that target different parts of the body) • Rhinovirus (common cold) • HPV(a virus that could lead to cervical cancer if left untreated) • Ebola • HIV

  16. Answer: • Overwhelming consensus: NO, viruses are NOT alive • Reasons people say “no”: Not made of cells, cannot reproduce on their own, don’t develop • Completelydependentupon a host to carry out functions • Reasons people say “yes”: Have genetic material and evolve

  17. Do Antibiotics Work Against Viruses? • NO, they work against BACTERIA • Target structures specific to bacteria(i.e., carbohydrate in their cell walls; specific type of ribosomes) • If a doctor tries to give you antibiotics for a cold, find a new doctor!

  18. Vaccines Against Viruses • What is a vaccine? • Vaccines are available for viruses that cause diseases such as the flu, chickenpox (but not in my day…), HPV, polio, and some types of meningitis A dead or weakened strain of a pathogen (disease-causing organism) that is given to expose the body to the pathogen in order to build immunity by creating antibodies

  19. Viruses & Cancer • Certain types of viruses can cause a person to be at a higher risk of developing certain types of cancers • HPV Cervical cancer • Hepatitis B & C  Liver cancer • HIV  Kaposi’s sarcoma (in the lining of blood & lymph vessels); types of lymphoma • Epstein-Barr  Burkitt’s lymphoma (although very rare and more common in Africa)

  20. Viral Outbreak! • Nipah Virus • Outbreak in 1999 (Malaysia & Singapore); spread from pigs to humans • Outbreak in 2018 (India); spread from bats to humans • Once a person is infected, can be spread directly between people through bodily fluids • Fever, headaches, vomiting, sore throat, muscle aches  dizziness, drowsiness, encephalitis, seizures, respiratory distress  Coma within 24-48 hours • Fatality rate of 40-75% • 20% of survivors develop seizure disorders and/or personality disorders; some may relapse

  21. Nipah Virus https://www.biointeractive.org/classroom-resources/virus-hunter-monitoring-nipah-virus-bat-populations

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