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Transcript of Bacteria (prokaryotes – no nucleus) Archaea (prokaryotes, but with similarities to next group) ...
Microbe DiversityChapter 13
Life is organized into 3 Domains
Bacteria (prokaryotes – no nucleus) Archaea (prokaryotes, but with
similarities to next group) Eukarya (eukaryotes – have DNA in a
nucleus)› Protista – single celled eukaryotes
Many different ways of feeding and living
Some are plant-like, some animal-like, and some fungal-like
› Metazoans – multi-cellular eukaryotes
Diverse and Everywhere
Viruses
Not cellular› DNA or RNA
genetic material› Inside a protein
coat Can’t reproduce
on own Parasitic on
cellular organisms
Reproduction of viruses Infects host cell by
attaching to outer surface › Injects genetic
material Virus DNA/RNA takes
over host cell’s metabolism to make its own components
New virus parts made, DNA/RNA replicated
Parts put together and then the host cell is lysed open
Note: host immune system has trouble finding the virus while it’s inside the host cell.
Viral Diseases
RNA viruses› No error checking
when replicating› Mutate quickly and so
vaccines must be updated regularly
› Common cold› Influenze can cause
worldwide epidemics DNA viruses
› Have error checking enzymes when replicate, so more stable
› Small pox – vaccine can give long term protection
Viruses can hide in host cell Chicken pox
› One of 8 Herpes viruses to infect humans
› DNA virus› Can lie dormant
in nerve cells for entire life
› Shingles = virus re-emerged later in life
Attacking Cancer with Viruses
Transductional Virotherapy uses viruses that recognize cell membrane receptors specific to cancer cells. › Virus attacks and multiplies in cancer cells
only
Transcriptional Virotherapy uses viruses that can use cancer specific DNA transcription promotor regions› Virus can enter all host cells, but can only use
the protein synthesis mechanisms of the cancer cell
Bacteria Prokaryotes
› No nucleus› Free ribosomes› No organelles
Circular DNA + small circles called plasmids› Plasmids have
been used to introduce foreign genes into bacteria
Unique forms of inheritance that only bacteria have.
Helpful bacteria Used to make yogurt,
cheese, wine, beer & vinegar.
E. coli live in your large intestine and help breakdown food
Also live elsewhere on body & help defend body from other species that might cause disease.
Important decomposers
Used to make medicines
Harmful bacteria Pathogenic bacteria
› Cholera› Plague› Tuberculosis› Tetanus – actually
waste product causes symptoms
› Syphilis Just harmful
› Acne› Strep throat› Plaque on teeth
Archaea Share characteristics
of bacteria› Size and shape› Prokaryote› Circular DNA› No RNA processing
Share characteristics of Eukarya› Histones associate
with DNA› DNA replication and
repair process› Other metabolic
pathways
Archaea con’t
Some characteristics uniquely Archaea› Cell wall has
unique molecular structure
› Cell membrane has unique components
› Some metabolic pathways unique
Many Archaea survive in extreme habitats Up to 122 º C (252 º
F) around thermal vents
Cold temperatures of polar oceans
Salt ponds at salinities of 20-25%
Sulfuric acid at pH 0 Alkaline
environments High pressure of
ocean floor (200 atm)
Uses for Archaea Hard to rear in lab Enzymes used in PCR
for DNA research Can be used to
breakdown oil and materials toxic to other organisms
Feed on minerals and can be used to eliminate mineral build up in power plant cooling systems.
Review Session
Gram staining
Aerobic Respiration
Anaerobic Respiration
Some bacteria use oxygen to generate cell energy.
Cyanobacteria were the first organisms to add oxygen to the atmosphere by photosynthesis. Still important oxygen producers today
Use alternative energy pathways and can’t function in the presence of oxygen.
Tend to be found in sludge at the bottom of lakes or in other places that lack oxygen.
If all of the earth’s bacteria disappeared tomorrow, which ONE of the following would be the MOST LIKELY and MOST DIRECT result?
A) There would be no more pathogens on earth.
B) Human populations would thrive in the absence of disease.
C) There would be little change in earth’s ecosystems.D) The recycling of nutrients would be
greatly reduced.E) The number of organisms on earth would decrease by 10–20%.
Which of the following does a bacterium NOT contain?
A) DNAB) ribosomesC) cytoplasmD) RNAE) mitochondria
With regard to their genomes, what is one major difference between viruses and bacteria?
A) Viruses cannot replicate their own nucleic acids; bacteria can.
B) Viral genomes can be replicated faster than bacterial genomes.C) Viruses can replicate their own nucleic acids; bacteria can’t. D) Viruses replicate using transduction; bacteria replicate using conjugation.E) Viral genomes are RNA; bacteria genomes
are DNA.
Protista
First Eukaryotes› Have a nuclear
membrane Double layer with pores Regulates the
molecules that interact with DNA
Probably formed as an in pocketing of the cell membrane
› Acritarch fossils 1.9 billion years old = first eukaryotes
Innovations Cell organelles› Some formed from
invaginations of cell membrane
› Some by endosymbiosis
› Performed specialized functions
Larger size Cell respiration
enables these cells to produce more energy› Can be more
active
Protista Diversity
Animal-like Protists
Move by cilia or flagella
Feed on other organisms› Phagocytosis › Endocytosis
Digested in food vacuole
Elimination by exocytosis
Plant-like Protists Photoautotrophs
› Feed themselves by capturing sun energy to make sugar molecules
› = Photosynthesis Euglena can also
hunt prey when little light is available
Some are colonial Some multicellular
forms are included = seaweed
Fungi-like Protists
Reproduce by spores Heterotrophic, but
digest outside of body
Tend to be sedentary and move by adding cells to colony› Slime molds can
form a creeping slug
Diseases caused by Protists Trypanosoma –
sleeping sickness Transmitted by
insect Vaccine difficult
because proteins of cell membrane change with every cell division
Leads to lethargy, coma and death
___________________ were the first organisms in the history of life on earth that could use solar energy to build organic compounds from CO2, and in the process break down water molecules to release oxygen.
A) CyanobacteriaB) ChemolithotrophsC) ChemoorganotrophsD) RetrovirusesE) Plants
In the United States, about 25 million pounds of antibiotics, more than eight times as much as used in human medicine, are used in:
A) global warming.B) ecological research.C) forestry.D) waste clean up.E) agriculture.
Protists are alike in that all are:
A) prokaryotic.B) multicellular.C) eukaryotic. D) marine. E) photosynthetic.
Paramecia are protists that resemble
A) PlantsB) FungiC) ArchaeaD) AnimalsE) Bacteria
Classified by shape
Cell membrane + Cell wall with
outer capsule layer
Pili on outer surface have various functions such as attaching to solid surface or moving across that surface