PROKARYOTES PLAY A CRUCIAL ROLE
IN THE BIOSPHERE (27-5)
C
PROKARYOTES HAVE BOTH
BENEFICIAL AND HARMFUL EFFECTS
ON HUMANS (27-6)
By: Jacob Pasley
Dedicated to: Dr. Burke
Prokaryotes Intro
• Singled cell organism
• Lack membrane bound nucleus
• Two major classification domains: the bacteria and archaea
• Founds in all types of habitats
• Many create large colonies
• Reproduce through Asexual reproduction; typically by binary fission
• Involves horizontal gene transfer
• transfer of genes that is not typical reproduction
• Four main structures or shapes
1.
2.
3.
4.
Cocci- spherical
Bacilli- rod shaped
Spirochaete- spiral-shaped
Vibrio- comma shaped
Decomposers
• Organism(s) that break down other
organisms; they are heterotrophic
• Heterotrophic- use organic substrates to get
energy, carbon, and nutrients for processes and
• Breaks down cells
• Convert tissues into metabolically useful
chemical products
• No need for internal digestion; thus no
technical “stomach”
• Use dead organisms and non living
organic compounds as a food source
Types of Decomposers
• Bacterial/Bacteria
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Can break down mostly any type of organic matter
1 gram of soil contains 40 million bacterial cells
More bacterial than plants or animals combined; large biomass
Vital in recycling nutrients
Used in nutrient cycle(s)
• Fungi
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Most grow in branching network(s) of hyphae
Can penetrate large pieces of organic matter unlike bacteria
Primary decomposers in the woods
Releases enzymes that breakdowns decaying material
Hyphae is used to breakdown matter and absorb corresponding nutrients
• When two fungi’s hyphae grow close to each other they fuse to form other fungi as
well
Types of Decomposers (2)
• Worms
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(contains slugs and snails)
Can be considered decomposers and also scavengers
A worm can remove the skin or various tissues to sped up decay
Can expose the elements or to other decomposers
Filers soil; filters out nutrients
Video
Overall Importance of Decomposers
• Decomposers help plants receive the nutrients necessary for vital
life processes
• Dead waster would pile up and matter would not decay
• Assists with Nitrogen Fixation
• where atmospheric nitrogen is filtered into organic compounds
(assisted, in part, by decomposers)
• Adds usable nitrogen
Types of Symbiosis
•Three types of Symbiosis
• Mutualism- both benefit
• Commensalism- one benefits with little effect on the host
• Parasitism- one benefits at the coast of the host
• Means a relationship between 2 or more organisms
Symbiosis Video
Pathogens
• (Can) produce disease
• It means “Infectious Host”
• Known as a microorganism (can include a virus, bacterium, prion, or
fungus)
• One of three P’s (predators, pathogens, and parasitoids)
• Beneficial in the sense that they can serve as biological controls and suppress
various (arthropod) pest populations
Pathogenic Prokaryotes
• Prokaryotes cause ½ of human disease
• This includes (famously) Lyme Disease
• Types
• Prior- infectious pathogens that do not include nucleic acids and
abnormally folded proteins
• Viral
• Bacterial- often killed by antibiotics, though resistance is an issue
• Fungal- usually saprophytes; common cause of disease in crops
and plants
• Other Parasites- such as protists and helminths
• However, can be used in healthcare in vaccinations as well
• Makes the immunity stay virulent against disease
Mutualistic Bacteria
• Mutualistic relationships exist between humans and
bacteria.
• the human intestine and digestive systems contains
up to 1,000 different species of bacteria
• 10 times more abundant than the total number of cells in
the human body
• Benefits: bacteria can help digest (break down)
food that the intestine can not efficiently digest
• Bacteria in the human digestive system (and other
digestive systems) also contain genes associated
with nutrients, vitamins, and carbohydrates (and
synthesis processes)
Mutualistic Bacteria (2)
• Gut (intestinal bacteria) sends signals that allows humans to
produce antimicrobial compounds
• Probiotic- dietary supplement that contains live bacteria (ACTIVA)
• Most bacteria are beneficial
• Examples
• Lactobacillus reuteri- protects human(s) from the effect(s) of microbes, lowers
cholesterol, and assists with the immune system
• Bacterial Flora- present in the human gut/ digestive system
Pathogenic Bacteria
• Cause bacterial infection
• Very few are pathogenic (infectious)
•Examples
•Tuberculosis- caused by Mycobacterium
tuberculosis
• Kills 2 million people each year
•Pneumonia- caused by bacteria such
as Streptococcus and Pseudomonas
Endotoxins
• A toxin that is present in the bacteria when a cell disintegrates
• Detailed by Richard Friedrich Johannes Pfeiffer
• In the cell, released only after the cell wall disintegrates
• Associated with lipopolysaccharide(s) and Gram-negative bacteria
• Some studies show endotoxins in the digestive system can cause obesity
Exotoxins
• Can cause damage to the host cell by
destroying it or disrupting cellular metabolism
• May be released during the lysis of the cell
• Lysis- breaking down of the cell
• Can be destroyed by heating
• So toxic that it can kill the host before the
immune system can respond
• A toxin that is released into the environment
***Note: both endotoxins and exotoxins are ways of enducing disease
Prokaryotes in Research
• Have led to important advances in DNA
research and technology
• Bioremediation
• The use of these organisms to remove pollutants
from the environment
• Used for
• Mining
• Synthesis of vitamins
• Production of antibiotics, hormones, and other
products
***Note: just and overview: video will provide further insight