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