Bacteria Characteristics: Morphology and Gram Staining

Bacteria Characteristics

• Basic bacterial morphology includes capsule and cell wall.
• Cell walls can be either gram-positive or gram-negative.
• Other important features include pili and flagella.
• Fimbriae are hairlike appendages that help cells adhere to other cells/substrates.
• Capsules are a sticky layer of polysaccharide or protein that aids in cell adherence and evasion of the host's immune system.
• Bacteria do not have membrane-enclosed organelles and typically lack complex compartmentalization.
• Flagella are structures used by most motile bacteria for propulsion.
• Pili are used as appendages that facilitate conjugation.
• There is a circular chromosome, plasmids can also be present as smaller rings of DNA.
• The cell wall is made primarily of peptidoglycan, a network of modified sugars cross-linked by polypeptides.

Gram-Positive vs. Gram-Negative Bacteria

• Gram-positive bacteria have relatively simple walls with a thick layer of peptidoglycan.
• Gram-negative bacteria have less peptidoglycan and a structurally more complex outer membrane containing lipopolysaccharides.

Prokaryotic vs. Eukaryotic Flagella

• Prokaryotic flagella are 1/10th the width of eukaryotic flagella and are not covered by an extension of the plasma membrane.
• Prokaryotic flagella are composed of flagellin, and include a motor, hook, and filament.
• Eukaryotic flagella are made of microtubules arranged in a "9+2" pattern composed of tubulin.
• Prokaryotic flagella rotate, driven by a motor at the base.
• Eukaryotic flagella whip, powered by dynein motor proteins causing bending.

Bacterial Reproduction and Genetic Recombination

• Bacteria reproduce asexually through binary fission.
• Genetic recombination occurs through transformation, transduction, or conjugation.
• An F+ cell contains an F plasmid, which gives it the ability to form pili for conjugation and to transfer DNA from a donor to a recipient.
• An F- cell lacks the F plasmid.
• Transduction is genetic recombination via the introduction of viral DNA into a bacterium.
• Transformation occurs when a prokaryotic cell's genotype and possibly phenotype are altered by the uptake of foreign DNA from its surroundings.
• Transduction occurs when bacteriophages carry prokaryotic genes from one host cell to another.
• Conjugation involves the transfer of DNA between two prokaryotic cells that are temporarily joined.

Autotroph vs. Heterotroph

• Autotrophs only need CO₂ or related compounds as a carbon source.
• Heterotrophs require at least one organic nutrient, such as glucose, to make other organic compounds.

Anaerobic vs. Aerobic Conditions

• Anaerobic conditions lack oxygen and obligate anaerobes are poisoned by O₂.
• Aerobic conditions contain oxygen, and obligate aerobes must use O₂ for cellular respiration.
• Facultative anaerobes can use O₂ if present, but can also carry out fermentation or anaerobic respiration in an anaerobic environment.

Autotroph Types

• Photoautotrophs: Have light as their energy source and use CO2, HCO3, or related compounds as a carbon source.
• Chemoautotrophs: Use inorganic chemicals (such as H2S, NH3, or Fe) as an energy source and CO2, HCO3, or related compounds as a carbon source.
• Photoheterotrophs: Use light as their energy source and organic compounds as a carbon source.
• Chemoheterotrophs: Use organic compounds as both an energy and carbon source.

Archaea vs. Bacteria

• Archaea have cell walls containing polysaccharides and proteins (but lack peptidoglycan), membrane lipids with branched hydrocarbons, several kinds of RNA polymerase, and use methionine as the initiator amino acid for protein synthesis.
• Some archaea species have histones associated with their DNA, can grow at temperatures over 100 degrees Celsius, and some contain introns.
• Bacteria have cell walls containing peptidoglycan, membrane lipids with unbranched hydrocarbons, one kind of RNA polymerase, and use formyl-methionine as the initiator amino acid for protein synthesis.
• Bacteria lack histones, cannot grow at temperatures over 100 degrees Celsius, and rarely contain introns.
• Archaea are single-celled prokaryotes without peptidoglycan in their cell walls and are found in extreme environments.
• Bacteria are single-celled prokaryotes with peptidoglycan in their cell walls.
• Eukarya are organisms with eukaryotic cells containing true nuclei, including both single-celled and multicellular organisms.

Archaea and Bacteria Commonalities

• Both lack a nuclear envelope and membrane-bound organelles.
• They both have a circular chromosome and reproduce through binary fission.

Bacteria Benefits

• Bacteria aid in digestive health.
• Intestinal bacteria produce vitamins.
• Bacteria are used in industrial applications like bioremediation.
• Certain bacteria synthesize polymers like polyhydroxyalkanoate (PHA) for biodegradable plastics.
• Bacteria are used in the production of antibiotics, vitamins, and other important products.

Bacteria and Disease

• Bacteria can cause diseases in humans through the production of toxins.
• Examples of pathogenic bacteria include those that cause Tuberculosis, Diarrheal disease and Lyme disease.
• Exotoxins are proteins secreted by bacteria while alive, and examples include Cholera and Botulism.
• Endotoxins are components of the outer membrane of gram-negative bacteria that cause severe immune responses; and are released after the bacteria die.

Protists

• Protists are a paraphyletic group of mostly unicellular, eukaryotic organisms and are diverse.
• Endosymbiosis explains the origin of certain organelles in eukaryotic cells like mitochondria and plastids.
• Theory says a prokaryotic cell engulfed another prokaryotic cell which then evolved into the mitochondrion.
• A eukaryotic cell engulfed a photosynthetic bacterium which then evolved into the chloroplast.
• Common characteristics among protists include mitochondria and membrane-bound organelles.

Giardia intestinalis

• Locomotion: Multiple flagella that are whiplike structures.
• Nutrition: Heterotrophic; absorbs intestinal nutrients.
• Reproduction: Primarily asexual through binary fission.
• Disease: Giardiasis.
• Ecological role: Parasite.

Trichomonas vagisilis

• Locomotion: Multiple flagella which are whiplike structures that propel the organism through its environment as well as an undulating membrane.
• Nutrition: Heterotrophic; ingestive; feeds on vaginal lining
• Reproduction: Primarily reproduces asexually through binary fission.
• Disease: Trichomoniases, a common STD.
• Ecological role: Parasite.

Trypanosoma sp

• Locomotion: moves using flagella which are whip-like structures
• Nutrition: Heterotrophic; chemoheterotroph
• Reproduction: Primarily reproduces asexually through binary fission.
• Disease: Sleeping sickness and Chaga's disease.
• Ecological role: Parasite.

Euglena

• Locomotion: uses 1 or 2 flagella.
• Nutrition: Mixotrophic; it can perform photosynthesis when sunlight is available. When sunlight is not available it can absorb organic nutrients from its environment.
• Reproduction: primarily though asexual reproduction.
• Diseases: none

Dinoflagellates

• Locomotion: 2 flagella; one propels through water the other is for rotation.
• Nutrition: Mixotrophic.
• Reproduction: Asexual reproduction through binary fission.
• Disease: Red tide which is toxic to marine life and humans who eat marine life.
• Ecological role: Phytoplankton, contributes to primary production in aquatic ecosystems.

Plasmodium

• Locomotion: Moves through different forms. Sporozoites move through the bloodstream to the liver; merozoites move within red blood cells.
• Nutrition: Heterotrophic (ingestive); feeds on host's cells and nutrients
• Reproduction: Sexual and asexual (alternation of generations.)
• Disease: Malaria.
• Ecological role: Parasite.

Ciliates

• Locomotion: Cilia beat in coordinated waves allowing the organism to swim.
• Nutrition: Heterotrophic (ingestive); feed on bacteria and other small particles. Uses cilia to sweep food into their oral groove where it is engulfed into food vacuoles by phagocytosis.
• Reproduction: Asexual and sexual; asexually through binary fission and sexually through conjugation.
• Diseases: No major diseases.
• Ecological Role: Control bacterial populations and recycle nutrients.

Amoeba

• Locomotion: Pseudopodia which are tube or lobe-shaped extensions of their cell membrane that allow them to crawl along surfaces.
• Nutrition: Heterotrophic; engulfs food particles through phagocytosis.
• Reproduction: Asexually through binary fission and sexually through the fusion of haploid amoebas which then go through meiosis then mitosis which releases haploid amoebas.
• Ecological Role: Controlling bacterial populations and recycling nutrients; some are symbiotic parasites infecting various animals.

Diatoms

• Locomotion: Nonmotile.
• Nutrition: Photoautotrophic.
• Reproduction: Asexual reproduction through binary fission and sexual reproduction through the formation of gametes and subsequent fertilization.
• Diseases: None
• Ecological Role: Photosynthesis and carbon sequestration as well as a primary food source for various marine protists and invertebrates.

Brown Algae

• Locomotion: Nonmotile.
• Nutrition: Photoautotrophic.
• Reproduction: Alternation of generations that includes sporophyte and gametophyte.
• Diseases: None.
• Ecological Role: Photosynthesis and habitat formation.

Oomycetes

• Locomotion: Nonmotile.
• Nutrition: Heterotrophic; decomposers.
• Reproduction: Asexual reproduction through zoospores and sexual reproduction through oospores.
• Diseases: Plant diseases like downy mildew and white rust as well as potato blight.
• Ecological Role: Decomposers and Parasites.

Red Algae

• Locomotion: Nonmotile.
• Nutrition: Photosynthetic autotrophs; some are heterotrophic and live as parasites on other red algae.
• Reproduction: Sexually; alternation of generations.
• Diseases: None.
• Ecological Role: Photosynthetic role and food source.

Green Algae

• Locomotion: Most are nonmotile; certain forms use flagella.
• Nutrition: Autotrophs.
• Reproduction: Asexually through cell division or formation of spores; sexually through the fusion of gametes.
• Diseases: None.
• Ecological role: Photosynthetic role and symbiotic roles providing photosynthetic products to their hosts.

Slime Molds

• Locomotion: Pseudopodia.
• Nutrition: Heterotrophs that consume through phagocytosis.
• Reproduction: Sexual reproduction involves the formation of fruiting bodies called plasmodial slime molds when conditions are unfavorable; asexual reproduction occurs when solitary cells aggregate and form fruiting bodies called cellular slime molds.
• Diseases: None.
• Ecological Role: Decomposers

Protist Characteristics

• Dinoflagellates possess cellulose plates, two flagella located in grooves and are mostly unicellular photosynthetic algae.
• Ciliates are covered in thousands of cilia, have a micronuclei and a macronuclei and are heterotrophs that ingest food through funnel-shaped grooves.
• Red and green algae are in the same eukaryotic supergroup as plants.
• Plasmodial slime molds form a single mass of cytoplasm called a plasmodium, and extend speduopodia to absorb food particles and when conditions are not favorable it forms fruiting bodies for sexual reproduction.
• Cellular slime molds consist of solitary cells that aggregate to form a slug-like structure.

Fungi

• Fungi are heterotrophs that feed by absorption through secreting enzymes that break down complex molecules into smaller organic compounds that they can absorb.
• Fungi consist of hyphae that form an interwoven mass known as a mycelium.
• Fungi can reproduce asexually through spores that germinate.
• Fungi reproduce sexually through the fusion of cytoplasm from two parent mycelia, followed by the fusion of nuclei to form a zygote. Meiosis then leads to the formation of spores.
• Hyphae are thin filaments that make up the body of a fungus, with mycelium as the interwoven mass.
• Hyphae secrete enzymes to break down organic matter and have a structure which maximizes nutrient absorption.
• Coenocytic fungi are fungi whose hyphae lack septa, resulting in a continuous cytoplasmic mass with multiple nuclei.
• Deuteromycetes are fungi that have no known sexual stage in their lifetime, also known as imperfect fungi.
• The predominant phase of life cycle in most fungi is haploid (n) stage

Fungi Groups

• The major groups of fungi are:
  • Cryptomycetes (e.g., Rozella)
  • Chytrids (e.g., B. dendrobatidis)
  • Zoopagomycetes (e.g., Entomophthora)
  • Mucoromycetes (e.g., Rhizopus)
  • Ascomycetes (e.g., S. cerevisiae)
  • Basidiomycetes (e.g., A. bisporus)
• Chytrids are the most primitive, diverging earliest from a unicellular flagellated protist ancestor.
• Yeasts reproduce asexually through ordinary cell division or by budding.
• Ascomycetes can reproduce asexually through spores called conidia which form at the tips of specialized hyphae called conidiophores.
• Ascomycetes can reproduce sexually which involves conidia of opposite mating types.
• Plasmogamy fusion results in heterokaryotic or dikaryotic cells which contain two haploid nuclei that fuse in karyogamy to form diploid cells for meiosis lead to genetically diverse spores.
• Mycelia is the filamentous mats formed by fungi.
• Lichens are a mutualistic association between a fungus, usually an ascomycete, and a photosynthetic alga or cyanobacterium

Fungi - Ecological Role

• Important ecological roles of fungi are decomposers, mutualists, and pathogens.
• Fungi decomposing a dead tree and releasing nutrients into the soil are examples of decomposers.
• Mycorrhizal associations with plant roots are an example of fungi being a mutualist.
• American chestnut blight is an example of fungi being a pathogen.
• The structures of fungi arranged in order from largest to smallest, assuming that they all come from the same fungus: Mycelium, Basidiocarp, Gills, Hyphae, Basidia, Basidiospores.
• Fungi are commercially important in food, cheese, cheese production, are used as brewery and baking yeasts, provide gourmet foods, provide medicine, supply antibiotics, conduct human glycoprotein and research.
• Certain fungi can synthesize hydrocarbons, decompose organic matter recycling nutrients back into the ecosystem.

Fungi- Plant Evolution

• Both fungi and plants faced the challenge of moving from aquatic to terrestrial environments.
• Early land enviornmet shad mineral nutrients but lacked organic matter.
• Both fungi and plants evolved to form mycorrhizal associations.
• Plants developed spores and apical meristems; while fungi formed extensive hyphae.

Plant Key Characteristics

• Key characteristics of a plant are vascular/non-vascular, xylem and phloem, spores, gamete, zygotes, homosporous/heterosporous, and micro/megaspores.
• Key characteristics of a plant include alternation of generations; apical meristems; multicellular dependent embryos; walled spores produced in sporangia; cuticle; and stomata.

Vascular vs Non-vascular Plants

• Vascular plants have vascular tissue, sporophyte dominance, are larger/more complex, and use vascular tissue for transport.
• Nonvascular plants lack vascular tissue, possess gametophyte dominance, are small and simple structured, and rely on diffusion and osmosis for transport.
• Xylem transports water and minerals from roots to shoots through transpiration.
• Phloem transports sugars from leaves to sugar sinks through pressure.
• Spores are produced by sporophytes and develop into gametophytes through mitosis.
• Gametes are produced by gametophytes and involved in fertilization to form a zygote.
• Zygotes form through fertilization and divide by mitosis to develop a sporophyte.

Homosporous vs Heterosporous Plants

• Homosporous plants produce one type of spore, which typically develops into a bisexual gametophyte.
• Heterosporous plants produce microspores and megaspores.
• Microspores develop into male gametophytes, produced by microsporangia on microsporophyll.
• Megaspores develop into female gametophytes, produced by megasporangium on megasporophyll.
• Seed plants appear 360 MYA further diversifying plant life.
• Plant adaptations for terrestrial existence are: cuticle; stomata; vascular tissue; seeds and pollen; mycorrhizae; and apical meristems.
• Bryophytes lack vascular tissues and have gametophyte dominance.
• Seedless vascular plants have sporophyte dominance.
• Gymnosperms produce naked seeds; and angiosperms produce seeds encased in fruits.

Spores vs. Seeds

• Spores are single-called, dispersal and reproduction in seedless plants contain no stored food and can be dispersed in a dormant state.
• Seeds are multicellular with protective coat and can be carried distances.
• Unique features of seed-producing plants include heterospory, reduced/microscopic gametophytes, ovules + pollen, and seeds.
• Ferns are homosporous with spores as the dispersal mechanism.
• Seed plants produce the megaspores, microspores via seeds.

Gametophyte vs. Sporophyte

• Gametophytes are haploid which produce haploid gametes by mitosis.
• Sporophytes are diploid which produce haploid spores by meiosis.
• Bryophytes-gametophyte dominant
• Seedless vascular plants and ferns-sporophyte dominant
• Embryophytes are plantae.

Flower Structure

• Flower parts include sepals, petals, stamens, and carpels.
• Petals are brightly colored to attract pollinators and sepals enclose the flower, before it opens.
• The male components (stamens) consist of a filament supporting an anther and filament.
• The female components consist of an ovary with an ovule, style: and stigma.
• Pollen tubes grow down the style when water is absorbed by the pollen grain.

Eudicots vs Dicots

• Eudicots have one cotyledon, parallel veins and scattered vascular tissue.
• Dicots have two cotyledons, netlike veins, and the vascular tissue aranged in a ring.
• Eudicots have a fibrous root system and pollen grain with one opening.
• Dicots tend to have taproot, with pollen grain containng three openings.
• In Eudicots, floral organs come in increments of 3, where as dicots exist in increments of 4-5.