Bacteria Flashcards
Name the three different shapes of bacteria (morphology).
Cocci (Spheres)
Bacilli (Rods)
Spirochetes (Spirals)
What is the function of the cytoplasm?
Site of biochemical reactions.
What is the function of bacteria DNA?
Contains genetic material for reproduction. It is NOT contained within a defined nucleus, and also found in plasmids.
What is a flagella?
Filamentous structure that aids the mobility of the bacterium.
What is a capsule?
Found on the outside of the bacteria and enhances the bacterium’s ability to cause disease.
What is the cell wall of a bacteria made up of?
Peptidoglycan.
What are the differences between gram positive and gram negative bacteria?
Gram positive have thick cell walls, that contain several layers of peptidoglycan. Goes purple during a gram stain.
Gram negative have thin cell walls and contain little peptidoglycan. Turns pink during a gram stain.
What are the four steps involved in a gram stain process?
- Stain cells with crystal violet
- Add iodine to improve the colour resolution of crystal violet dye.
- Decolorisation. Add alcohol (ethanol). Gram positive have thick cell walls, preventing the alcohol to enter. Gram negative have thin cell walls so the alcohol can enter clearing the crystal violet.
- Add safranin. This turns the colourless gram negative cell pink, and does not effect the gram positive cell - leaving it purple.
What are the 4 types of flagella distribution?
Monotrichous - one flagellum at one end of the cell
Lophotrichous- multiple flagella at one or both ends of the cell.
Amphitrichous - one flagellum at each end of the cell.
Peritrichous - flagella that covers the whole surface of the cell.
What is a bacterial endospore?
They are protective, highly resistant structure that allow bacteria to survive in hostile environments.
They are cryptobiotic, meaning they show no signs of life.
How is an endospore formed?
- DNA is copied. A wall is formed, separating the two copies of DNA in the mother cell. This creates a cell within a cell.
- Peptidoglycan surrounds the outside of the endospore. This layer is called a cortex.
- Water is removed. Outside of the cortex another layer called a spore coat is added (protein coat).
- The mother cell is destroyed, and the endospore bursts out.
Name three conditions that a bacterial endospore can survive.
- High Temperatures
- Irradiation
- Desiccation
- Strong Acids
- Organic Solvents
- Disinfectants
What is binary fission? Describe the process.
Binary fission is how bacteria reproduce asexually.
The DNA of the bacteria is copied inside the bacteria.
The chromosomes are pulled to separate sides, and the cell starts to divide.
The cells then produce a cell membrane around the two cells, creating two identical haploid cells.
What is conjunction? Describe the process.
Conjunction is how bacteria pass on their genetic material to other bacteria, allowing resistance to pass onto a population quickly.
Small protein tubes called Pili are located on the outer layer of bacteria. The Pili attaches itself to the host bacteria and transfers a copy of the plasmid into the host bacteria.
