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?