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Why were the first cells likely Prokaryotic?
- Prokaryotic cells are a simpler than Eukaryotic cells.
- Evidence from microfossils and stromatolites support this theory.
What is a microfossil?
Rock layer of undisturbed continental crust. Evidence of ancient prokaryotic cells.
What is a stromatolite?
Sedimentary deposits covered with mats of bacterial cells that trap mineral deposits. Evidence supporting prokaryotic cells being the first cells.
Why is carbon fixation thought to be an ancient process?
Higher levels of carbon-12 has been noted in fossils than in surrounding rock.
It is estimated that only ____% of prokaryotic species are known.
____ and ____ are the oldest, simplest and most abundant life forms.
Archaea and Bacteria.
*Probably existed a billion years before eukaryotes.
Where do prokaryotes live?
Prokaryotes live EVERYWHERE!
Even in places where eukaryotes cannot live.
True or False: Many archaea and bacteria are extremophiles.
False. Only archaea are extremophiles.
Archaea that exisit in extreme heat conditions.
Halophiles love... ?
Halophiles are a type of archaea that thrive in extremely salty conditions.
What is a methanogen?
A type of extremophile archaea that generates methane gas. Commonly found in sewage plants.
What are the defining characteristics of a prokaryote?
- Cell size - Smaller than eukaryotes
- small circular DNA- PLASMIDBinary fission
- No internal compartmentalization
- Singular flagellum
- Metabolic diversity
Are Prokaryotic cells always unicellular?
How small are most Prokaryotic cells?
Most prokaryotic cells are between 0.5 and 5 micrometers or less in diameter.
How do prokaryotes multiply?
Through a process called Binary fission
Why don't prokaryotic cells have internal compartmentalization or membrane bound organelle?
These cells are far too small for compartments.
What is a plasmid?
A plasmid is a small, circular accessory DNA molecule found in the nucleoid region of a prokaryotic cell.
How many flagella does a prokaryotic cell have?
Prokaryotic cells have a singular flagella
How does a prokaryotic cell get energy?
Prokaryotic cells can use energy stored in chemical bonds from inorganic molecules to make carbs
In what four ways do Archaea and bacteria differ?
- 1. Plasma membrane
- 2. Cell wall
- 3. DNA replication
- 4. Gene expression
What are the traditional characteristics that were used in early classification of prokaryotes?
- 1. Photosynthetic or non-photosynthetic?
- 2. motile or non-motile
- 3. Unicellular or colony-forming or filamentous
- 4. Formation of spores or division by transverse binary division
- 5. Importance as human pathogens or not
What approach is used today to classify cells?
A more molecular approach to classification may help reflect true evolutionary relatedness.
What are the 3 basic forms of prokaryotic cells?
Rob-shaped, Cocci and Spiral form
_____ is the single most important contributor to cell shape.
The Bacteria Cell Wall
What substance is found in the cell walls of bacteria but NOT in archaea?
If a bacteria cell has a flagella, this means they most likely live in ____?
Filamentous bacteria move in a _____.
Describe the differences between Gram-negative and gram-positive bacteria.
- Gram positive: Thicker peptidoglycan wall, stains purple
- Gram negative: Less peptidoglycan present in wall, dye dark pink--Sandwich membrane
Gram-positive bacteria stain:
Gram-negative bacteria stain:
Dark pink: because the have less peptidoglycan to retain purple dye.
In bacteria, what is a capsule and what does it do?
gelatinous, surrounds other wall layers and adherent, helps bacteria to evade immune response (ie: the bacteria that stick to your teeth)
- anchored in the cell wall
- spin like a propellr
- cell can move throgh liquid
hairlike structures on some gram-negative prokaryotes; shorter than flagella; important in adhesion; may have role in exchange of genetic info
Pili are only present in some gram-_____ bacteria.
What is an endospore?
consist of thick wall around genome and small portion of cytoplasm, form in response to environmental stress (drought, etc)
Why are spores important?
Spores help protect prokaryotes from extinction.
Do spores last forever?
Spores germinate and divide once environmental conditions improve
Name three examples of diseases that can form spores
T or F: Prokaryotic cells do not reproduce sexually
What are the three ways that bacteria can exchange DNA with one another?
bacteria transfers DNA to other bacterial cell horizontally via SEX PILI
This method of cellular DNA exchange involves viruses.
Bacteria picks up genetic material from the external environment. Whole plasmid is taken up by bacteria from environment.
Antibiotic resistance can be transferred between bacteria by _______
What is a resistance plasmid and why is it important?
A resistance plasmid is a plasmid that has developed or acquired resistance to antibiotics, etc. Important because this allows bacteria to survive.
Name a bacteria that has acquired resistance plasmids
What is MRSA?
Methicillin resistant S. aureus.
What is VRSA?
Vancomyacin resistant S. Aureus
Variations in bacteria can also arise from _____
Prokaryotic metabolism consists of four types:
- Photosynthetic bacteria
- Example: cyanobacteria (self feeders that use light)
- Oxisize inorganic compounds
- Example: Nitrifiers (Self feeders that use chemicals)
Where are nitfifiers commonly found and what purpose do they serve?
- Nitrifiers are found on the nodules of legumes (beans, nuts, etc)
- Nitrifiers rejuvenate soil on farms with nitrogen.
- use light as a source of energy but obtain carbon from organic molecules
- Example: purple and green nonsulfer bacteria
- obtain both carbon AND energy from organic molecules
- Example: majority of prokaryotes, including decomposers and most pathogens
Note: Humans and all nonphotosynthetic eukaryothes are chemoheterotrophs too.
How do photoautotrophs meet their energy needs and how to they get their carbon?
Photoautotrophs make their own carbon from the energy they receive from light
How do chemoautotrophs meet their energy needs and how to they get their carbon?
Chemoautotrophs make their own energy and carbs from oxidizing inorganic compounds
How do photoheterotrophs meet their energy needs and how to they get their carbon?
Photoheterotrophs use light as their source of energy, but get carbon from organic molecules
How do chemoautotrophs meet their energy needs and how to they get their carbon?
Chemoheterotrophs obtain both carbon and energy from organic molecules
T of F: Some bacteria can attack other cells directly
Give an example of a bacteria that can attack other cells directly
Yersinia pestis causes what?
How does yersinia pestis attack other cells?
- This bacteria releases protiens through it's cell walls
- these proteins may transfer other, virulent proteins into eukaryotic cells
How is yersinia pestis (Bubonic plague) commonly spread?
Through rats and fleas
What are pseudomonads?
Gram-negative, rod-shapped bacteria that cause plant diseases such as blights, soft rots, and wilts
Pseudomonads are (gram-negative/positive), (cocci, spiral, or rod shaped) bacteria that attack plants.
Disease spreads by means of:
mucous, saliva, contaminated food/water, insect vectors
Clostridium botulinum causes?
Chlamydia trachomatis causes
Corynebacterium diphtheriae causes:
Helicobacter pylori causes:
Yersinia pestis causes:
Name some beneficial prokaryotes
Beneficial bacteria responsible for releasing dead organism's atoms back into the environment
return elements from inorganic form to organic forms that heterotrophs use
What are the two types of fixation?
- Carbon fixation
- Nitrogen fixation
Define carbon fixation
involves incorporating the carbon from CO2 inro complex organic compounds
Define nitrogen fixation
involves certian bacteria converting N2 gas to ammonia (NH3) and then to nitrate (NO3)
Distinguish between mutulism, commensalism, and parasitism
- Mutulism: Both parties benefit
- Commensalism: One organism benefits while the other is neithe harmed or helped
- Parasitism: One organism benefits while the other is harmed
Give an example of mutulism
bacteria in roots of plants, cellulase-producing bacteria in gut of cattle, bacteria in human intestines that produce vitamin B12 and K
Example of Commensalism:
Bacteria on surface of animals or plants in which the bacterium benefits and the host isn't harmed or helped
Example of parasitism
Explain how bacteria is used in engineering and give an example
Bacteria is used to produce pharmaceutical agents such as Insulin, also in production of ensymes, vitamins, and antibiotics. Also used in production of commercial products.
How is bacteria used in bio-remediation?
Bacteria is engineered to clean up and resolve undesirable situations such as:
- sewage treatment plants
- cleaning up oil spills
- removal of contaminants from ground water