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Bacteria - Page Text Content

S: AP Biology 2012


FC: Bacteria | Michelle | Brittany | Grace

1: So... what do you know about bacteria? Here are some questions for you. Try and see how many you can answer by the end of the presentation. | What is kind of bacteria can be traced through fossil records to the Precambian era? | What is the size range for most bacteria? | What is the main method of bacterial transportation? | What bacterial structure is needed for conjugation? | What method is used to distinguish between gram + and gram - bacteria? | Where are bacteria found? | What do bacteria eat? | What is a heterotroph?

2: SIZE AND SHAPE | - The average size of a bacteria is between 0.5 and 2 micrometers | There are several different shapes of bacteria. They include... | 1. Coccus a.Chain: streptococcus b.Cluster: staphylococcus 2. Bacillus a.Chain: fastreptobacillus | 3. Coccobacillus 4. Vibrio 5. Spirillum 6. Spirochete 7. Square 8. Star

3: Square Bacteria: | Spirochete: "Long, helically coiled spiral shaped cells" | Coccus Cluster: "A facilitative anaerobic gram positive bacterium" | Coccus Chain: "Cocci that fail to separate after they divide, but instead remain in chains of cells.

4: BACTERIAL STRUCTURES | The Flagella | Gives the organism movement | Flagella are long appendages which rotate by means of a "motor" located just under the cytoplasmic membrane. | Bacteria may have one, a few, or many flagella in different positions on the cell.

5: Bacterial Structures: The Pili | Short appendages that are made up of protein and are much smaller than the flagella. | The F-Pili, or sex pili, is used in conjugation to exchange DNA | Allows the bacteria to float by increasing its boyancy EX: Pellicle

6: Bacteria Structure: Capsule | Also called the "Slime Layer" | Usually made up of Glycocalyx-Polysaccharide, but sometimes protein | Adheres the bacteria to surfaces | Most associated with harmful bacteria since it protects against phagocytosis, by the white blood cells. | CAPSULE

7: Bacteria Structure: Cytoplasm | Made up of 20% salt and protein and 80% water | Contains the bacteria's circular, haploid DNA, which is more efficient and grows quicker | Holds the plasmids, which are extra pieces of DNA | NO Organelles!

8: Bacteria Structure: Cell Membrane | Much like the plasma membrane of other cells... | - Consists of a Bilayer Phospholipid | - Water can penetrate | - Flexible | - Not strong; Ruptures easily due to osmotic pressure

9: Bacteria Structure: Cell Wall | - Determines the shape of the cell | - Is strong, which prevents the osmotic rupture that the weak membrane can't stop. | - Unique to bacteria: made up of peptide-glycan polymer | - 20% to 40% of bacteria have a cell wall

10: Bacteria Structure: Teichoic Acids | Bacteria Structure: Endospores | - The attachment for phages - Only present in Gram + Cells - Made up of glycerol, phosphates, and ribitol. | - Form in dry environment, and are resistant to harsh environments like, heat, desiccation, radiation, chemicals, acids, and drying | - Takes both time and ergy for a cell to form a spore | -Located within the cell | - Not really a spore but a dormant form to which the bacterium can reduce itself often triggered due to lack of nutrients

11: Bacteria Structure: Lipopolysaccharide (LPS) | - "The major component of the outer membrane of Gram-negative bacteria, contributing greatly to the structural integrity of the bacteria, and protecting the membrane from certain kinds of chemical attack." | - An endotoxin that causes disease when destroyed | G+ Bacteria: | G- Bacteria: | - Has a thicker cell wall - Has teichoic acids | - Contains endotoxins, or LPS

12: Overview of Cell Structures


14: Bacteria's | Look where these live... | Don't I just look lovely. Think of what I could do to . ......you | Actually Bacteria does a lot for Humans

15: Niche | Actually... Bacteria does a lot for Humans. | Actually Bacteria does a lot for Humans. | THE GOOD...(Probiotics) | THE BAD | L.Acidophilus- commonly used . in yogurt L. Lactis- found in most cheeses L. reuteri- present in human milk Streptomyces- used to synthesize . antibiotics Rhizobium- supplies ammonia to plants | Salmonella- the course of . salmonella, or the . sickness you get . from raw chicken streptococcus- strep-throat staphylococcus- staph. . infections of . wounds | Did you know... that bacteria are necessary in almost every natural cycle including the nitrogen cycle, decomposition, and carbon fixing

16: Where in the world is bacteria ? | bacteria are found everywhere except for areas sterilized by humans...

17: You can find bacteria in lakes, seas, soil, in tissues of plants and animals... even in Antarctica ! | you can even find bacteria in him!!

18: NUTRIENTS | bacteria have a wide range of diets. Some are heterotrophs and some are autotrophs | Most heterotrophic bacteria are saprobes (they absorb dead organic material like rotting flesh). Some of these parasitic bacteria kill their host while others help their host.

19: Autotrophic bacteria make their own food, either by photosynthesis (which uses sunlight, carbon dioxide and water to make food) or by chemosynthesis (which uses carbon dioxide, water and chemicals like ammonia to make food - these bacteria are called nitrogen fixers and include the bacteria found living in legume roots and in ocean vents) | Staphylococcus epidermis

20: Types of heterotrophic bacteria | Lithotrophs | Organotrophs | Chemoheterotrophs | Photoheterothrphs

21: Types of Autotrophic bacteria | -photo-autotrophic -chemo-autotrophic

22: Evolu | THE PAST | Fossil of blue-green algea (cynobacteria) from the Precambrian era. Approx. 3.5 billion years old. | Bacteria are considered prokaryotes and although considered more 'simple' than eukaryotes much about them is unknown

23: tion | THE PRESENT | The current form of blue-green algae. It is one of the least changed organisms on the planet | Their age though, has led to great variety with in bacteria themselves. They have evolved into diverse shapes and forms and to utilize differing food sources.

24: A Cladogram of Bacteria based on DNA sequences that encode ribosomal structure

26: How is Bacteria Classified? | Before... | Classified on the basis of... | - Shape: - Bacilli: rod shaped - Cocci: spherical - Spirilla: Curved - Ability to form spores - Method for energy production: - Glycolysis (anaerobes) - Cellular Respiration (aerobes) - Nutritutional Requirements - Reaction to Gram Stain

27: The Gram Stain: | 1. Bacterial Cells are stained with a purple dye, called crystal violet | 2. Treated with alcohol or acetone to wash the stain out of the gram-negative cells | 3. Redyed in pink safranin; this is called a counterstain. Those that are recolored the second time are the gram-positive | Useful in distinguishing between the two very different kinds of cell walls

28: Classification of Bacteria | NOW... | - Genome Sequencing of bacteria's RNA, specifically their rRNA. | Advantages of comparing DNA sequences of bacteria are... | - DNA is much easier to sequence - DNA is more stable, so there is a greater possibility of sequencing DNA on extinct organisms.


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  • By: Bacteria A.
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  • Title: Bacteria
  • A project we had to do for AP Biology on Bacteria. Here is the result of our three days.
  • Tags: biology, school, Bacteria
  • Published: over 4 years ago

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