Chapter 27 Flashcards
Are prokaryotes multicellular or unicellular?
Unicellular
Look at figure 22.7: what three shapes are most common in prokaryotes?
Spherical (cocci), rod shaped (bacilli), and spiral (spirilla)
What is the composition of the typical bacterial cell wall?
Rather than being made of cellulose or chitin, it is made up of peptidoglycan- a polymer composed of modified sugars cross-linked by short polypeptides. It encloses the entire bacterium and anchors other molecules that extend from the surface.
Look at figure 27.3: explain the difference between gram-positive and gram-negative bacteria.
Gram-positive bacteria have a thick wall made of peotidoglycan.
Gram-negative bacteria have a thin layer of peptidoglycan, which is located between the plasma membrane and an outer membrane
Why would a gram staining procedure be very valuable in treating a patient? Consider why certain antibiotics are only effective on one type of bacteria or the other?
It is an easy way to determine if an infection is due to a gram-positive or gram-negative bacteria. Gram-negative bacteria have a more complex structure and outer membrane as opposed to the more simple gram-positive bacteria
What are antibiotics? Why are they becoming less effective?
Drugs that kill bacteria. Bacteria that have some resistance to the drug are becoming more successful and reproducing.
Describe what a plasmid is and why it is important for bacteria.
A small circular double stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome. They can be uptaken as well as replicated and transferred to other cells
If bacteria only reproduce asexually, how do they maintain the diversity needed for evolution?
Transformation: uptake DNA from surroundings
Transduction: bacteriophages transfer DNA
Conjugation: DNA transfer when temporarily joined by sex pilus
What is horizontal gene transfer? How is it accomplished in bacteria?
Gene transfers between different species. Transformation, transduction, and conjugation.
Prokaryotes can be placed in four groups according to their mode of nutrition, which is how they take in carbon and how they obtain energy. Use table 27.1 to help you list each and summarize how each of them obtains energy.
Photoautotroph: light energy source, C from CO2 or HCO3-.
Chemoautotroph: inorganic chemical energy source, C from CO2 or HCO3-
Photoheterotroph: light energy source, C from organic compounds
Chemoheterotroph: organic compound energy source, C from organic compounds
Explain what a biofilm is, give an example, and explain their importance.
A surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation. Dental plaque. They help form the capsule or slime layer.
Many archae love on the edge of where life can exist, what are these organisms called and what are some examples of where you may find these organisms?
Extremophiles. Highly saline, sulfur-rich volcanic Springs, etc
There are many bacterial diseases. Make a list of three that you find most interesting in your text and briefly describe their effects.
Lyme disease: carried by ticks that live on deer and field mice. Can result in arthritis, heart disease, nervous disorders, and death.
Cholera: caused by an exotoxin secreted by a protobacterium and stimulates intestinal cells to release chloride ions into the gut, and water flows by osmosis which results in diarrhea
C. Diff: produces exotoxins that causes severe diarrhea
Explain how a normally harmless symbiont of our gut, E. coli, can be the agent of serious food poisoning.
Different DNA parts are introduced into some bacteria by phages (transduction) which enable the bacteria to attach to the intestinal wall and extract nutrients
Not all bacteria activity is negative. Humans employ bacteria for many diverse activities. Cite three human applications using prokaryotes in research and technology here.
- they provide food for small organisms
- used to clean up oil spills
- mass production of insulin
