Life on Earth Topic 7: Procaryotic Organisms

1. Life on EarthTopic 7: Procaryotic Organisms Part of the Evolution of Australian Biota Module Biology in Focus, Preliminary Course Glenda Childrawi and Stephanie Hollis

2. DOT Point • Describe technological advances that have increased knowledge of procaryotic organisms • Describe the main features of the environment of an organism from one of the following groups and identify its role in that environment • Archaea • Bacteria uhh.hawaii.edu

3. Introduction Procaryotesare single-celled organisms. They are the smallest, simplest organisms. They are abundant in the air, water, soil, and on most objects. It’s believed that live as we know it has evolved from these organisms bio.m2osw.com

4. Technology Structural methods of classifying procaryotic organisms in the past have been very valuable however, these methods did not always reflect the organisms’ possible evolution. textbookofbacteriology.net

5. Technology New technological advances have changed the way procaryotic organisms are now classified, and increased our understanding and knowledge of biological structures, chemical composition and biochemical (genetic) characteristics. uhsecho.com

6. Technology The light microscope has allowed us to identify cells as being unicellular and small with a cell membrane and cell wall. The electron microscope allowed us to see fine details including organelles and DNA. microscope-microscope.org

7. Technology Chemical analysis has allowed us to determine the chemical composition of cytoplasm and membranes. Genetic sequencing has allowed us to determine the number of chromosomes and further explore genetic material. nhchemicalanalysis.com

8. Technology These developments, due to technology, in our knowledge of present day organisms allows for a better understanding of the origins of life and the processes involved in the evolution of living things. nrc-cnrc.gc.ca

9. Technology For example, we now know that bacteria have evolved along two main evolutionary lines, classified as kingdoms-Bacteria and Archaea wired.com

10. Bacteria Bacteria are an enormously diverse group that share many environments with, or live on and in humans and other animals and plants. These are habitats of moderate temperature with water freely available, low in salt and where sunlight and organic compounds are plentiful. answersingenesis.org

11. Bacteria Oxygen is not so important since many of the bacteria have powerful fermentation capabilities, producing ATP (energy) under anerobic conditions. The group bacteria contains almost every variety and combination of biochemical energy extraction and carbon-fixation thought to be possible. science.howstuffworks.com

12. Bacteria However, this group also contains some of the most specialised and sensitive cellular organisms known. These are often pathogens that have become highly adapted to particular environments within animal or plant hosts. herryyudha.com

13. Bacteria Cyanobacteria resemble algae and plants in that they contain chlorophyll and generate oxygen during photosynthesis. They occur as individual cells or as filamentous aggregates of many individual cells joined end to end. serc.carleton.edu

14. Bacteria Cyanobacteria contains pigment called phycobilins which give them a blue-green appearance. They often form dense mats of growth in shallow marine or estuarine environments. Scientists believe this bacteria is responsible for the oxygen in our atmosphere. futurity.org

15. Bacteria Endospore-forming bacteria are the most resistant form of life known. Endospores form inside the mother cell rather than budding from it. They form under conditions of nutrient depletion or as a result of other environmental signals forewarning difficult times ahead for the bacterium. www2.raritanval.edu

16. Bacteria Endospores appear to have evolved as a resistant, virtually metabolically inactive cell type, increasing the probability of survival under extreme conditions such as cold, heat or desiccation. kswfoodworld.wordpress.com

17. Bacteria Bacterial endospores are remarkably resistant to high temperature, high radiation and many chemicals which would rapidly destroy all other living cells. Clostridium tetani lives in anerobic environments en.wikipedia.org/wiki/Endospore

18. Archaea Archaea are still commonly referred to as archaebacteria, however, this term has been discarded as they are not bacteria. Archaea are a more specialised group than bacteria and its members are therefore more restricted to the environments they inhabit. microbiologyonline.org.uk

19. Archaea Archaea are single-celled, microscopic organisms which do not contain any membrane bound organelles. They do not require sunlight for photosynthesis, nor do they require oxygen. scienceline.org

20. Archaea Most live in extreme environments and are called extremophiles, however, some still live in ordinary temperatures, salinities and acid levels. • Thermophiles live in water temperatures greater than 50C • Halophiles live in hypersaline environments greater than 9% and up to 32% salt concentration • Acidophiles live in acidic environments lower than pH 2 and as low as pH 0.9 green-buzz.net

21. Archaea By studying these organisms that presently live in extreme conditions on Earth, we are able to infer what the organisms were like that survived during the extreme conditions of early Earth. news.sciencemag.org

22. Homework -Students to complete DOT Point 3.5 **Hand out Holiday Research Activity and discuss** green-buzz.net