Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell Diversity and Photosynthesis Diversity of MetabolismsDiversity of Metabolisms PhotosynthesisPhotosynthesis

Larry M. Frolich, Ph.D.Biology Department, Yavapai College

Cell Diversity and Photosynthesis

• Diversity of MetabolismsDiversity of Metabolisms

• PhotosynthesisPhotosynthesis

• Prokaryotic and Eukaryotic CellsProkaryotic and Eukaryotic Cells

• Prokaryotes—Archaea and BacteriaProkaryotes—Archaea and Bacteria

• Eukaryotes—Protists, Plants, Eukaryotes—Protists, Plants, Fungi, AnimalesFungi, Animales

• Viruses and PhagesViruses and Phages


Basic metabolic requirements

• Energy to build carbon chains

• Oxygen…sometimes

• Nitrogen, Iron and other chemicals

• Physical environment


Energy and Carbon sources


Depending on carbon and energy source:

• Photoautotrophs: CO2, light

• Photoheterotrophs: organics, light

• Chemoautotrophs: CO2, chemical

• Chemoheterotrophs: organics, chemical

Thought question: Which is most common among macrobiological organisms? What are we?


Photosynthesis overview



Photosynthesis I. Light reaction(Photosystem I and II are part of this)





Photosynthesis II. Calvin cycle


Other chemical requirements

• Nitrogen: necessary component of amino acids and nucleotides, can be limiting, nitrogen-fixing bacteria (Rhizobium) very important in food chain

• Iron, may be limiting factor in bacterial survival (reading from “Why we get sick?”)

• Common ions: sodium, phosphorous, potassium, chlorine, magnesium, calcium


Physical aspects of cell’s environment

• Temperature—how hot is it?

• pH—how acid is it?

• Water osmotic pressure—how salty is it?

• Water hydrostatic pressure—how deep is it?

• More on these factors in Unit III


Overview of Diversity


Prokaryotes—simple cells with no organelles

The primitive Archaea are frequently "extreme-o-philes," including these heat-tolerant forms that live in hot springs

Electron micrograph of rod-shaped bacteria--Bacillus?


Prokaryotes—simple cell division, no chromosomes


• Typical shapes of prokaryotic cells

• Cells are tiny—as small as 1 micron


Archaea• Archaea are a group of

bacteria-like prokaryotes that are believed to be very close to the root of the tree of life

• Characteristics of Archaea (different from bacteria): – Lack peptidoglycan in cell

wall – Cell membrane lipids with

branched hydrocarbon chains

– AUG start codon for protein precursor is methionine (like eukaryotes) and not N-formylmethionine (like bacteria) Archaea in solar evaporation ponds near San Francisco

Bay--often have red or orange pigment to protect them from intense solar energy


Principally "extremophiles“– live in harsh

environments: – Thermophiles – Halophiles--highly saline

habitats like Dead Sea, Great Salt Lake and solar evaporation ponds for salt production

– Methanogens--obligate anaerobes in high methane environments--deep sea vents, colons of animals, sewage treatment plants

Archaea


Bacteria Cell Shapes and Groupings

Bacilli—ball-shaped bacteria

Cocci—rod-shaped bacteria


• Lots of bacterial groups!! Lots of bacteria!!

• closeness of disks shows similarity of rRNA sequence

See course website for link to images, descriptions of bacterial groups


Eukaryotes

• Ciliates• Have cilia

around cell to propel and encounter environment

• Paramecium being devoured by Didinium (at right)


• Apicomplexans

• All pathogens of animals

• Includes Plasmodium--protozoan that causes malaria (life cycle at right)

Eukaryotes


• Dinoflagellates• photosynthetic

using carotene and chlorophylss

• make up large part of freshwater and marine plankton

• Often have protective "skeleton" of silica (at right) that frequently forms fossils

• Many are bioluminescent

• Some produce neurotoxins that can poison fish are people who handle infected fish

Eukaryotes


• Amoebae• not clear where

amoebae belong in taxonomic scheme or if they are all related

• all feed and move with pseudopodia

• lack mitochondria • include

Radiolarians and foraminifera (planktonic forms with silica and calcium carbonate armor)

• At right is typical amoeba and Radiolarian

Eukaryotes


• Euglenozoa• have

choloroplasts • lack cell walls

and have flagella • plant allies or

animal allies--own kingdom??

• Euglena, at right, is classic example

Eukaryotes


• Soil decomposers • Mycorrhizae--fungal filaments on roots of plants (90% of plants have

them) help to absorb minerals and water • Nutritious food source--mushrooms • Important spiritual source--hallucinogenic forms • Produce antibiotics (penicillin, etc.) • Food preparation--bread, alcohol, citric acid for soft drinks and other

prepared drinks) • All fungi reproduce by cell division or asexually • Almost all have sexual reproduction by budding, asexual spores or

sexual spores on thalli or fruiting bodies (large mushrooms are example) • Basidiomycota is mushroom group • Ascomycota is mold and yeast group • Zygomycota is small, mostly parasitic group, also includes some molds

Eukaryotes-- Fungi


Penicillin with asexual spores at ends


• symbiotic fungus and cyanobacteria growing together

• sometimes algae replaces cyanobacteria

• sometimes not symbiotic in that fungus kills photosynthetic component

• important soil forming organism--break down new rock

• good air quality indicators--do not grow in polluted environment

Eukaryotes-- Lichens


• Seaweed is multicellular algae--most seaweeds have single-cell part of life cycle

• Many algaes only live as single-celled form

• Important component of marine plankton, especially diatoms

• Several groups of algaes--green algae, red algae, yellow, golden and diatoms, brown algae

• Diatoms have cell walls, composed of silica and cellulose--the silica often fossilizes and forms huge diatomaceous deposits much sought-after by gardeners for their high silica content and light weight porous nature

Eukaryotes-- Algae

Diatom frustrules (two halves fit together like petri dish)


• Previously grouped with fungi, but significant differences

• Water molds decompose dead animals in aqueous environment, also parasitic forms--Irish Potato famine caused by Phytophthora or late blight, still most damaging potato crop disease to this day.

• Slime molds may represent early forms of sexual reproduction--complex life cycle with large multi-nucleated, mobile (in amoeba-like form), synchtiums.

Eukaryotes– Water Molds and Slime Molds


Viruses and Phages

• All are obligatory intracellular parasites--need to be inside a prokaryotic or eukaryotic cell to reproduce

• Viruses infect eukaryotic cells; phages infect prokaryotic cells

• Virus particles, when outside of cells, cannot be seen in light microscope--size is 10-300 nm

• Particle consists of nucleic acids surrounded by one or two protein coats and sometimes protein appendage


Viruses and Phages

Viruses reproduce by making copies of proteins and nucleic acids inside host celll


• Viruses are characterized and grouped according to what kind of nucleic acids are found in the particles, and therefore how they reproduce themselves within cells. RNA viruses require reverse transcriptase (to go from RNA to DNA) which has been very important in genetic engineering:

• viruses types are dsDNA, ssDNA, ssRNA, dsRNA, retroviruses (ds=double-stranded; ss=single-stranded)

• Viruses do not all causes infectious diseases and may be involved in normal development or secondary factors in cancers, diabetes and other conditions

• Viroids are small circular pieces of RNA without any protein capsid that infect plants

• Prions ("PROteinaceous INfective agents) are proteins that can convert cells into a disease state

Viruses and Phages

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Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell Diversity and Photosynthesis Diversity of MetabolismsDiversity of Metabolisms PhotosynthesisPhotosynthesis