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An overview

Prokaryotes. An overview. What to Expect:. These notes focus on Cell theory Prokaryotes. Cell theory. All living things are made of cells Cell can only come from other cells All functions of a living thing are carried out in cells

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An overview

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  1. Prokaryotes An overview

  2. What to Expect: • These notes focus on • Cell theory • Prokaryotes

  3. Cell theory • All living things are made of cells • Cell can only come from other cells • All functions of a living thing are carried out in cells • Reminder: the functions of living things are: respiration, metabolism, growth, adaptations to the environment, reproduction, homeostasis and interdependence

  4. On your worksheet • State the 3 points of cell theory. • List the 7 characteristics of life

  5. There are two main groups of cells, prokaryotic and eukaryotic cells. Similarities: all are alive, all have a cell membrane, all have DNA Differences: appearance, structure, reproduction, and metabolism. • biggest differences are between cells of different kingdoms . 

  6. On your worksheet • List the 2 types of cells

  7. Where do we find Prokaryotes?

  8. Prokaryotes are bacteria • Prokaryotes are simple organisms VS Diagrams courtesy - http://www.cod.edu/people/faculty/fancher/ProkEuk.htm

  9. According to current scientific thought;Prokaryotes were formed 2 billion years before eukaryotes (or about 3.5 billion years ago)

  10. On your worksheet • According to current scientific thought, about how old are prokaryotes?

  11. Prokaryotesfrom the Greek meaning “before nuclei”

  12. Why “before nuclei?” • Prokaryotic cells have no nucleus. • Prokaryote’s DNA is circular (it has no ends). • Small circlets of DNA are called Plamids. • Prokaryotic DNA is “naked” – it has no histones associated with it and does NOT form chromosomes

  13. On your worksheet • What does prokaryote mean? • Why is the term prokaryote used to describe the cells we are talking about?

  14. bacteria Cyanobacteria also known as blue-green algae All Prokaryotes are in the monera kingdomdomains Bacteria and Archaea

  15. On your worksheet • What kingdom to do all prokaryotes belong to?

  16. Prokaryote Characteristics • Very small size. • Lack membrane-bound organelles inside the cell • have few internal structures that are distinguishable under a microscope. • genetic information is in a circular loop called a plasmid • Strong cell walls: resistant to environmental changes

  17. Size • Bacterial cells are very small, roughly the size of an animal mitochondrion • about 1-2µm in diameter and 10 µm long • µm = one millionth of a meter, or equivalently one thousandth of a millimeter.

  18. Video:

  19. On your worksheet • What is the size of an average Prokaryote?

  20. 2. Lack membrane-bound organelles inside the cell

  21. 3. have few internal structures that are distinguishable under a microscope. http://www.umanitoba.ca/science/biological_sciences/lab3/biolab3_2.html#Examine

  22. 4. genetic information is in a circular loop called a plasmid • E. coli cell dividing. • E. Coli Grows in human intestine; • Has a single, circular chromosome • contains DNA as plasmids • Plasmids are extra-chromosomal DNA http://www.bio.mtu.edu/campbell/prokaryo.htm

  23. 5. Strong cell walls: resistant to environmental changes

  24. On your worksheet Describe the 5 items used to classify a prokaryote

  25. Cocci - sphereBacilli - rodsSpirilla – spirals Staph - in clustersStrep - in chains Spiral Rod shaped Spherical Shapes This spiral shaped bacteria is the causitive agent of syphilis Treponema pallidum Streptococcus sp. Chains of nearly-spherical bacteria.From The Rockefeller University.

  26. cocci Means Sphere-shaped Streptococcus sp. Chains of nearly-spherical bacteria.From The Rockefeller University. Streptococcus pyogenes

  27. Spirilla Means Spiral-shaped This spiral shaped bacteria is the causitive agent of syphilis Treponema pallidum

  28. Bacilli Means Rod-shaped

  29. Intermediate Shapes • short rods - (coccobacilli). • commas - (vibrii).

  30. Rare shapes squares stars irregular

  31. groups or clusters Cocci can divide to form • chains (streptococci) • groups of 4 (tetrads) • irregular clusters (staphylococci).

  32. groups or clusters Real-life examples:

  33. Bacilli can divide to form chains (streptobacilli) • spiral bacteria normally remain as separate individuals.

  34. To review:

  35. Or, how bacteria move bacterial motility

  36. overview of info • Some bacteria can be identified by how they move • Stationary (don’t move at all) • Flagella (whip like structure) • Rotation and tumbling • Number of flagella • Monotrichous • Lophotrichous • Amphitrichous • Peritrichous • Spiraling • Slime and ooze

  37. remain stationary • Which means, some bacteria simply do not move - - at all, ever.

  38. flagella • Some bacteria are propelled (moved) by a whip-like structure called a FLAGELLA • Flagella can be rotated like tiny outboard motors • When flagella rotation is reversed, bacteria tumble about in one place.

  39. Arrangements of flagella • Monotrichous-Having one flagellum at only one pole or end • Lophotrichous- having a tuft of flagella at one end • Amphitrichous- having flagella at both ends • Peritrichous- Having flagella uniformly distributed over the body surface

  40. spiral Like a corkscrew • Kinking different parts of the bacteria body by hardening one side and then the other

  41. Slime and ooze • Other bacteria secrete a slime layer and ooze over surfaces like slugs. • slime layer is formed by decomposition of the cell wall.

  42. Replication • Binary fission • one cell splits into two cells, • offspring are genetically identical to parent

  43. Bacterial conjugation • a form of sexual reproduction where bacteria exchange genetic information before dividing • offspring have new genes (and new traits) Figure 1. Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus; 2- Pilus attaches to recipient cell, brings the two cells together; 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipent cell; 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili. Both cells are now viable donors. http://parts.mit.edu/igem07/index.php/Boston_University/Conjugation

  44. Transformation • bacteria incorporate genes from dead bacteria • Transduction • viruses insert new genes into bacterial cells. • This method is used in biotechnology to create bacteria that produce valuable products such as insulin

  45. Movement Some can't move, while others have long threadlike flagella. If bacteria doesn’t move, how does it get from person to person? E.Coli flagella

  46. How does a Bacteria get energy?

  47. Metabolic Diversity Or, how bacteria get energy

  48. overview of info • 4 main ways bacteria get energy • Chemoheterotrophs • Photoheterotrophs • Photoautotroph • Chemoautotroph • Energy is released through either cellular respiration or fermentation • Oxygen demands vary • Obligate aerobe • Obligate anaerobe • Facultative anaerobe

  49. Heterotrophs • Heterotrophs get energy by eating other organisms • Chemoheterotrophs • Eat other organisms for Energy • Eat other organisms for carbon supply • Photoheterotrophs • Use sunlight for energy • Eat other organisms for carbon supply

  50. Heterotrophs • At least 95% of life on earth is heterotrophic (including people) staphylococcus aureus • Chemoheterotroph • “eat” same foods as humans • Release toxins that cause food poisoning • Antibiotic resistant strains cause breakout pictured here

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