The Single Cell: Viruses, Bacteria, & Protists. Why are levels of organization important? What do...
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Transcript of The Single Cell: Viruses, Bacteria, & Protists. Why are levels of organization important? What do...
The Single Cell:Viruses, Bacteria, & Protists
Why are levels of organization important?
What do you notice as the levels go from atom to organism?
Once at the organism level how do we organize?
Structure:Viruses, Bacteria, & Protists
DNA or RNA
DNA viruses: - Herpes simplex virus (HSV)
What is a Virus?
Classification on basis of nucleic
acid RNA viruses: - influenza virus
½ to 1/100 the size of the smallest bacteria
Structure of a Virus?
Envelope – additional layer surrounding the capsid
Capsid - a shell of protein surrounding nucleic acid
Proteins determine the viruses shape:
Polyhedral - papilloma virus
helical - tobacco mosaic virus
with projections - HIV
Polyhedral head w/cylindrical tail w/ leg fibers
Envelope Lipid bilayer
Capsid
Genetic material
Kingdom ArchebacteriaKingdom ArchebacteriaProkaryote Prokaryote Extreme environmentExtreme environmentNo free ONo free O22
High salt or sulfur concentrationHigh salt or sulfur concentrationSome produce methaneSome produce methane
What are Bacteria?
Kingdom Kingdom EubacteriaEubacteria
Human pathogensHuman pathogens
DecomposersDecomposers
Symbiotic livingSymbiotic living
Prepare foodPrepare food
Make antibioticsMake antibiotics
What are Bacteria?
Structure of BacteriaProkaryotic cells lack a nucleus and membrane
bound organelles
Common shapes among prokaryotes are spheres, rods, & spirals
Unicellular, multicellular, colonial
Eukaryotic
Aquatic environments
Kingdom Protista All organisms that are neither animals, plants, bacteria
or fungi are called 'protists'
What are Protists?
Plant like Protists - AlgaeLive in fresh or salt water
Reproduction & metabolism similar to plants
What are Protists?
Animal like Protists - ProtozoaAquaticAll are single celled
Metabolism similar to animalsGrouped according to how they move
Ciliate
Flagellate
Pseudopod
Sporazoan
Fungus like Protists – plasmodium, slime mold, downy mildewBehavior & metabolism similar to fungus
Reproduction:Viruses, Bacteria, & Protists
Viral Reproduction Lytic Cycle
The viruses attaches to a host cell and deposits its DNA The viral DNA instructs the host cell to use its own enzyme raw material & energy to only make new viruses The new viruses burst from the host cell – killing it – & are able to go infect other cells
•Attachment•Entry•Replication•Assembly•Release
Viral Reproduction Lysogenic Cycle
The viral DNA is integrated into the host cells chromosome - provirus
Every time the host cell replicates it also replicates the viral DNA
Once activated, the provirus enters the lytic cycle replicates and kills the host cell
•Attachment•Entry•Provirus formation•Replication•Assembly•Release
Most prokaryotes have a Most prokaryotes have a single, circular, double-single, circular, double-stranded DNA chromosome stranded DNA chromosome condensed in the nucleoid condensed in the nucleoid region of the cytoplasmregion of the cytoplasm
Bacterial Reproduction
Many bacteria have an additional small Many bacteria have an additional small ring of DNA – The ring of DNA – The Plasmid Plasmid – prokaryotes – prokaryotes can survive without the plasmid the genes can survive without the plasmid the genes for essential functions are on the for essential functions are on the chromosome. Plasmids sometimes contain chromosome. Plasmids sometimes contain genes for resistance and other special genes for resistance and other special issues issues
Prokaryotes reproduce mostly asexually via binary fission, making DNA almost continuously
Bacterial Reproduction ASEXUAL
No cell cycle like seen in Eukaryotes
No mitosis or meiosis
Translation and transcription
occur simultaneously
Allows for rapid response to Allows for rapid response to
Environment – Environment – ADAPTATIONADAPTATION
Conjugation, one cell directly transfers DNA to another
Resulting in a bacterium with a new genetic composition
Bacterial Reproduction SEXUAL
Plant Like Protist Reproduction Asexual & Sexual
Conjugation occurs when two filaments form conjugation tubes. The contents of one cell passes through the tube an fuses with a cell from the other filament. Fertilization occurs and a zygote is formed.
Fragmentation occurs when a filament breaks apart and each piece develops into another organism.
Spirogyra
(haploid)
(haploid)
(haploid)
(diploid)
(diploid)(diploid)
Alternation of generations Sexual and asexual reproduction occurs during alternating periods in the life cycle of the plant like protist.
Multiply asexually by fission. The cell divides into two individuals.
Animal Like Protist Reproduction
Paramecium undergoing fission.
Fungus Like Protist Reproduction Plasmodium - Reproduces by haploid sporesSlim molds are haploid their entire life & reproduce by cell division
Metabolism:Viruses, Bacteria, & Protists
Do viruses need energy?
Do viruses produce waste?
Do viruses need to “eat”?
Do viruses have a metabolism?
Heterotrophic BacteriaUse organic molecules as a food source
Obtain nutrients from living organismsObtain nutrients from living organisms
Unable to produce organic moleculesUnable to produce organic moleculesParasitesParasites –
SaprophytesSaprophytes – Feed on dead organisms or organic Feed on dead organisms or organic
wastewasteBreak down nutrients locked in body Break down nutrients locked in body tissues tissues of dead organismsof dead organisms
Excretes waste thru cell Excretes waste thru cell wall wall
Excretes waste thru cell Excretes waste thru cell wall wall
Autotrophic BacteriaUse sunlight to make organic molecules
PhotosynthetPhotosynthetic autotrophsic autotrophs – Contain Contain
chlorophyllchlorophyllExcretes waste Excretes waste thru cell wallthru cell wallMake organic molecules from inorganic ones
Chemosynthetic Chemosynthetic autotrophsautotrophs – Obtain energy needed to make food Obtain energy needed to make food fromfromChemicals like sulfur & nitrogenChemicals like sulfur & nitrogenExcretes waste thru cell wallExcretes waste thru cell wall
Plant like Able to perform photosynthesis contain chlorophyll
Not all are green. Diatoms & dinoflagellates have yellow to brown chloroplasts. There are brown algae & red algae
Release waste thru cell wall
Animal likeHeterotrophic – feed on other organisms or dead organic matter. Some are parasitic
Have specialized organelles used to release waste
Protists
Heterotrophic
Plasmodium Eats as it moves
Mildew Feed on dead organisms
Releases waste thru cell membrane
Fungus like
Gas Exchange:Viruses, Bacteria, & Protists
Do viruses need oxygen or carbon dioxide?
Why is gas exchange important?
Obligate aerobes – require oxygen
Mycobacterium tuberculosisMycobacterium tuberculosis – –the organism that causes the the organism that causes the lung disease tuberculosislung disease tuberculosis
Obligate anaerobes – require NO oxygen
Treponema pallidum – Treponema pallidum – the bacterium that the bacterium that causes syphiliscauses syphilis
Bacteria Metabolism
Prokaryotes used infolded regions of the plasma membrane to perform many
metabolic functions, including cellular respiration and photosynthesis.
Respiratory membranes in aerobes
Thykaloid membranes in photosynthetic bacteria
Heterotroph Autotroph
Bacteria Metabolism
Protists MetabolismProtists are eukaryotic cells
Have many specialized organelles including mitochondria or chloroplasts used in cellular respiration
Protists are aerobic – they require oxygen
Paramecium
Homeostasis:Viruses, Bacteria, & Protists
What is HOMEOSTASIS?
Why is it important?
How do VIRUSES maintain homeostasis?
The cell wall maintains the shape of the cell, protects the cell, and prevents the cell from bursting in a hypotonic environment
Bacteria Homeostasis
When life gets rough some bacteria can form resistant endospores
Endospores contain a bacterium’s DNA and a small amount of cytoplasmEndospores are encased in a tough outer covering that resists drying out and extreme temperatures
Star-shaped contractile vacuoles are used to balance the amount of water in the cell. Two nuclei contain the genetic information.
Amoebas can grow to very large sizes. Some species are 5 mm long! They can survive by having many nuclei within
their single cell.
If you would keep Euglenoids in the dark they start feeding on organic matter and may loose their chloroplast. Sometimes classified as animal like other times classified as plantlike
Protist Homeostasis Because the kingdom protista contains such a variety, several homeostatic behaviors exist
Are viruses alive?
How do How do characteristics of characteristics of
virusesvirusescompare to that of compare to that of living organisms?living organisms?
What are the What are the characteristics of characteristics of
life?life?
Maintain
Homeostasis
Metabolism
Reproduction
Cellular organization
Genetic information
Are viruses alive?How do How do characteristics of characteristics of virusesvirusescompare to that of compare to that of living organisms?living organisms?
Use host
cell’s
metabolism
No cell organization
Unable to
reproduce with out
a host cell
Has genetic material
Homeostasis?