Single-celled organisms. Very tiny. Cannot be seen without a microscope. Our microscopes are not powerful enough. Lack a nucleus and most other organelles. Most numerous organisms on Earth. Extremely important organisms..
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Prokaryotes Biology What are Prokaryotes?
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What are Prokaryotes?
Cannot be seen without a microscopeOur microscopes are not powerful enoughLack a nucleus and most other organellesMost numerous organisms on EarthExtremely important organisms.Slide3
Classification and Evolution
Prokaryotes are split into 2 Domains
Domain Archaea Everything else on Earth is in Domain Eukarya Prokaryotes were the first living things to evolve, around 3.8 billion years agoOnly living things on earth until 2 billion years ago
Until 1970s, Archaea were considered to be bacteria (called
) As more was learned about them, they were given their own domain because they are VERY different from bacteriaSlide4
Made up of bacteria
kingdom-BacteriaMost abundant living things on Earth.Live in almost every environmentAirOceanSoil
Estimated number of bacteria on earth: 5x10
30You have 10 times more bacterial cells than human cells!Slide5
Classification of Bacteria
Thousands of bacterial species exist.
Many are classified by shape.
Others are classified based on the color that they stain (Gram staining) Slide6
Structure of Bacterial Cells
Bacterial cells are surrounded by a plasma membrane
Most also have cell walls
Surrounding the membranes and cell wall (if present) is a capsule, which further protects the cellsInside of the bacterial cell is cytoplasm, similar to eukaryotic cellsFloating in the cytoplasm are ribosomes and plasmids (small sections of DNA)There is no nucleus
Instead, there is a Nucleoid
(area with DNA) and may be plasmids (circular DNA) to be exchanged with other bacteria
Bacterial cells also may contain whip-like structures called flagella Also have hair-like protrusions called pili that allow them to attach to objectsSlide8
Structure of Bacterial CellsSlide9
How do bacteria get energy?
Some are photosynthetic
Others decompose organic matter
Some can use chemicals from the environment to do a process similar to photosynthesis (called chemosynthesis)MutualismGetting resources from other species, while providing some service to that species (+/+)Parasitism
Stealing resources from host organisms (+/-)Slide10
Bacteria and People
You may think that bacteria’s purpose is to make us sick
For some bacteria, this is true
For many others, it is notBenefits of BacteriaCreate medicine, such as vaccinesHelp us digest foods and get vitamins Decompose wastes
Fix Nitrogen into usable forms for plants
Make foods such as cottage cheese, yogurt, cheese, and many more.Slide11
Dark side of Bacteria
Some bacteria can lead to disease
tetani Tetanus aka Lockjaw Affects muscles (including the heart). Leads to muscle spasms, and can be fatal.
(E. Coli)Many strains exist in human intestines in a commensalism relationship. However, some can cause food poisoning. Transmitted by fecal-oral route. WASH YOUR HANDS AFTER USING THE BATHROOM!!!Salmonella
Cause Typhoid fever (very fatal) and Food Poisoning
Transmitted by fecal-oral route. WASH YOUR HANDS AFTER USING THE BATHROOM
Second deadliest infectious disease (After HIV/AIDS). Yersinia pestis “The Bubonic Plague” or “The Black Death
Killed over 1/3 of the European Population between 1347 and 1353Slide13
A child and a portrait of a soldier affected with tetanus Slide14Slide15Slide16
If you have a weak stomach, please look away now…Slide17Slide18
Spread of the Black DeathSlide19
Artist drawing of a typical street during the spread of the black death.Slide20Slide21
At least the Plague is over… Right?Slide22
Bacteria in food and water can be killed by cooking at a high temperature
Bacteria on surfaces can be killed with cleaning products such as bleach or Lysol
Antibiotics can be used to kill bacteria that are harming humansEffective against bacterial infections such as strep throat, sinus infections, ear infections, pneumonia, etc.However, there is a problemSlide23
Antibiotic Resistance in Bacteria
Some bacterial species are evolving resistance to antibiotics.
www.youtube.com/watch?v=znnp-Ivj2ek The antibiotic kills those that are not resistant, but leaves the one that are resistantExample: Clostridium difficile
A common bacteria that causes diarrheal disease in hospitals. Hospitals, due to their obsessive cleaning procedures, have selected for resistant strains. Patients are being infected at a high rate, while staying in hospitals.Slide24
Even more alarming…
Remember how we just learned that Tuberculosis is the 2
most deadly infectious disease… Well…Tuberculosis is spreading due to becoming resistant to the antibiotics typically used to treat it.One strain is totally resistant to ALL drugs currently usedAnother is resistant to 3 of the 6 drugs used to treat it.Slide25
Genetic Diversity in Bacteria
Bacteria reproduce asexually (without sex)
Called binary fission
One bacteria replicates its DNA and then splitsMakes clones-identical copiesBenefit: Quick, little energy used, don’t need a mateDisadvantage: No genetic diversity
Susceptible to extinction
Conjugation is a way bacteria can increase genetic diversity
Exchanging all or part of a plasmid with another bacteriaNo longer identical Slide26
Antibiotic Resistance and Evolution by Natural Selection
Organisms must adapt to changing environments or they will die off
Called natural selection
As organisms adapt, the frequency of alleles (traits) in the population changeEvolutionBacteria, because they reproduce asexually, are able to quickly adaptThe antibiotic kills the weak ones and eliminates them as competition for strong ones.
They will rapidly reproduceSlide27Slide28
Only 1 Kingdom
Called Archaea (Surprised?)
ProkaryotesFirst discovered in extreme environmentsOriginally classified as bacteriaAs more was learned about them, they were found to be VERY different from bacteriaTheir cell wall is more similar to Eukaryotes than bacteria
They were given their own Domain and Kingdom
Very little is known about these organismsSlide29
Archaea: Tiny but Tough
Many archaea are extremophiles
Organisms that have evolved to live in extreme conditions.
Example: Hydrothermal vents in the ocean (picture) are very acidic and hot. Would kill most organisms, yet archaea thrive.4 types of extremophiles
Halophiles-Survive in very salty water (Dead sea)
Hyperthermophiles- Survive at high heats
Some archaea can survive up to 122° C (252° F)Acidophiles-Live in highly acidic environments (like near volcanoes)
-Live in very basic environmentsSlide30
Where else do they live?
chaea do not only live in extreme environments
They are found nearly everywhere on Earth.Including in humans (many are found in the human belly button!)Around 4 % of human microbiome The microorganisms that live on or in us
They are also important decomposers, and part of Nitrogen cycle
Many archaea also form symbiotic relationships
None are known parasitesMost form mutualistic relationshipsArchaea in cattle gut help break down grass and straw, and get nutrients in return
Prokaryotes Biology What are Prokaryotes? - Description
Singlecelled organisms Very tiny Cannot be seen without a microscope Our microscopes are not powerful enough Lack a nucleus and most other organelles Most numerous organisms on Earth Extremely important organisms ID: 694875 Download Presentation
Eubacteria & . Archarbacteria. Prokaryotes. Unicellular organisms that lack a nucleus. Prokaryotes are identified by characteristics such as shape, the chemical nature of their cell walls, the way they move, and the way they obtain energy..
Prokaryotic . Structure. size1-5. m. m (resolution of the human eye ~750. m. m). . Cell wall. . main component is peptidoglycan (modified sugar polymers). . can be further differentiated performing a gram stain .
Cell Theory. Every living organism consists of one or more cells.. The cell is the structural and functional unit of life.. All living cells arise by division of preexisting cells.. Cells contain hereditary material, which they pass on to their offspring during division..
GTAC. Learning Outcomes. Students recognise that there are different levels of classification – the largest being the five kingdoms which are based on cell structure.. Distinguishing plant cells from animal or fungal cells..
Cellular organisms. In one of two domains: . Archaea. and Eubacteria. Generally smaller than eukaryotes. Most are unicellular, some form colonies or filaments. No membrane-enclosed organelles. Ribosomes are located in the cytoplasm.
Biology Unit 04 Lesson 01. Prokaryotes – What are they?. Cells (usually single-celled) with no nucleus. Have no specialized organelles. Usually have: cell wall, cell membrane, ribosomes, genetic material, cytoplasm, and flagella or cilia.