Chapter 11 pdf (continued)

Gram(-) proteobaceteria

• Largest and most diverse group of Bactria

• 5 classes:

  • Alphaproteobacteria

    • Nitrogen fixers (Nitrofying)

    • Nitrobacter

    • 2 genera important for agriculture

      • Azospirillum

      • Rhizobium

    • Purple nonsulfur phototrophs

    • Pathogenic:

      • Rickettsia

      • Brucella

    • Others:

      • Acetobacter

      • Gluconobacter

      • Caulobacter

  • Betaproteobacteria

    • Pathogenic:

      • Neisseria

      • Bordetella

      • Burkholderia

    • Others:

      • Thiobacillus

      • Zoogloea

      • Sphaerotilus

  • Gammaproteobacteria

    • Largest and most diverse class of proteobacteria

    • Subgroups:

      • Purple sulfur bacteria

      • Intracellular pathogens

        • Legionella

          • Causes Legionnaires’ disease

        • Coxiella

          • Causes Q fever

      • Methane oxidizers

        • Use methane as a carbon and energy source

        • Inhabit anaerobic environments

      • Glycolysis faculatative anaerobes

        • Catabolize carbohydrates by glycolysis and the pentose phosphate pathway

        • Divided into 3 families

          • Enteroacteriaceae

          • Vibrionaceae

          • Pasteurellaceae

      • Pseudomonads

        • Break down numberous organic compounds

        • Important pathogens of humans and animals

          • Pseudomonas causes urinary tract, ear and lung infections

        • Azotobacter

        • Azomonas

  • Deltaproteoacteria

    • Desulfovibrio

    • Bdellovibrio

    • Myxeobacteria

  • Epsilonproteobacteria

    • Campylobacter

    • Helicobacter

Other Gram(-) bacteria:

• Chlamydias

  • Grow intracellular in mammals, birds and some invertebrates

  • Some are smaller than viruses

  • Most common sexually transmitted bacteria in the United States

• Spirochetes

  • Motile bacteria that move in a corkscrew motion

  • Have diverse metabolism and habitats

  • Treponema and Borrelia both cause disease in humans

• Bacteroids

  • Bacteroids

    • Inhabit digestive tracts of humans and animals

    • Some species cause infections

  • Cytophaga

    • Aquatic, gliding bacteria

    • Important in the degradation of raw sewage

Chapter 12 pdf

Classifying/characterizing Eukaryotes:

• microorganisms

  • Protozoa

  • Fungi

  • Algae

  • Water molds

  • Slime molds

Eukaryotes include:

• include both human pathogens and organisms vital for human life

• Marine algae called diatoms together with a set of Protozoa called dinoflagellates provide the basis for the ocean’s food chains and most of the world’s oxygen

• Eukaryotic fungi produce penicillin, and bakers/brewer’s yeasts are essential for baking and alcoholic beverages

• Pathogenic eukaryotes include

  • Wide variety of agents we will cover in depth at a later date

• Reproduction:

  • Can reproduce both sexually (meiosis), asexually (mitosis) and Gamete fusion (fertilization)

  • DNA stores in nucleus

  • Nuclear division

    • Has one or two complete copies of genome

      • Single copy (haploid)

        • Most fungi, many algae, some Protozoa

      • 2 copies (diploid)

        • Remaining fungi, algae, and Protozoa

    • 2 types of nuclear division

      • Mitosis

      • Meiosis

Mitosis:

• cell partitions replicated DNA equally between 2 nuclei

• Maintains policy of parent nucleus

  • Haploid nucleus that undergo mitosis forms 2 haploid nuclei

  • Diploid nucleus that undergoes mitosis produces 2 diploid nuclei

• 4 phases:

  • Prophase

    • Cell condenses its DNA into chromatid

    • 2 sister chromatids join a central region called a centromere to form one chromosome

    • microtubules form spindle in the cytosol

    • Nuclear envelope disintegrates so that the remaining shares occur freely in the cytosol

  • Metaphase

    • Sister chromatids line up on a plane in the middle of the cell and attach ear their centromeres to the microtubules of spindle

  • Anaphase

    • Sister chromatids separate and move along the microtubules to the piles of each spindle

    • Each chromatid is now called a chromosome

  • Telophase

    • Cell restores its chromosomes to their less compact state and nuclear envelope forms around daughter nuclei

    • A cell might divide telophase, but mitosis is nuclear division, not cell division

    • Cell division is called cytokinesis

Meiosis:

• nuclear division that partitions chromatid into 4 nuclei

• Diploid nuclei produce haploid Daughter nuclei

  • Contain half the amount of original DNA

• 2 stages:

  • Meiosis I

  • Meiosis II

  • Each stage has 4 phases:

    • Prophase

      • Early prophase I

        • DNA replication during interphase results in pairs of identical chromatids joined at centromeres, forming chromosomes

        • Chromosomes carrying similar or identical genetic sequence line up side-by-side, each consists of 2 chromatids

      • Late prophase I

        • Homologous chromosomes exchange sections of DNA in random fashion in a process called “crossing over”

        • Can last days or longer

    • Metaphase

      • Metaphase I

        • Tetrads align on a central plane at the center of the cell and attach to the spindle microtubules

        • Homologous chromosomes remain as Tetrads

    • Anaphase

      • Anaphase I

        • Homologous chromosomes of tetrads carrying crossed-over DNA, move apart from one another

    • Telophase

      • Telophase I

        • First stage of meiosis is completed as the spindle disintegrates

        • Cell typically divides at this stage to form 2 cells

        • Nuclear envelopes may form, through prophase II may begin immediately without nuclear envelope forming

  • Meiosis II is essentially a repeat of Meiosis I

    • Telophase II results in 4 haploid cells

Cytokinesis:

• typically occurs simultaneously with telophase of mitosis

• Plants and algae have a cell plate form

• Protozoa and some fungal cells divide by microfilaments that “pinch” the cell

• Single-called fungi form a bud

Protozoa:

• unicellular

• Lack cell wall

• Motile by mean of cilia, flagella and/or pseudopods

  • Except large groups

• Require moist environments

  • Most live in lakes, ponds, streams, oceans

• Free-living or parasites

• Very few are pathogens

• Others live in moist soil, beach sand, and decaying organic matter

• 2 nuclei

  • Macronucelus

    • Contains copies of genome

  • Micronucleus

    • Involved in genetic recombination

• Resting stage is called a cyst

• Feeding stage is called a trophozoite

• Most are Chemoheterotrophic

  • Has to eat things for energy

• Most reproduce asexually

  • Binary fission

  • Schizogony:

    • Multiple mitosis

• Few produce sexually

  • Conjugation

• Groups:

  • Parabasalid

    • Lack mitochondria

    • Have multiple flagella

    • Have single nucleus

    • Contains parabasal body

    • Undulating membrane

    • Important:

      • Trichomonas

  • Diplomonadida

    • Lack mitochondria

      • Have mitosomes

    • Lack Golgi bodies and peroxisomes

    • Have 2 equal-sized nuclei and multiple flagella

    • Can form a cyst

    • Important

      • Giardia

  • Euglenozoa

    • Have 2 flagella

    • Mitochondria have disk-shaped cristae

    • Groups:

      • Euglenids

        • Photoautotrophic

        • Some feed by phagocytosis

        • Lack cell walls

        • Have flagella

        • The “red-eye” spot helps to detect light

        • Reproduce via binary fission

      • Kinetoplastida

        • Have a single large mitochondrion

        • Some are pathogenic

          • Trypanosoma

            • African sleeping sickness

            • Chaya’s disease

          • Leishmania

            • Through sandfly

  • Alveolates

    • Membrane-bound cavities called alveoli

    • Divided into 3 subgroups:

      • Ciliates

        • Numerous cilia

        • Chemoheterotrophs

        • Balantidium

          • only ciliate pathogenic to humans

      • Apicomplexans

        • Chemoheterotrophic

        • Pathogenic

        • Plasmodium, Cryptosporidium and Toxoplasma cause disease in humans

          • Malaria, Cryptosporidiosis, toxoplasmosis (respectively)

      • Dinoflagellates

        • Unicellular

        • Photosynthetic pigments

        • Large proportion of freshwater and marine plankton

        • Motile ones have 2 flagella

        • Bioluminescent

        • Abundance is what causes “red tide”

        • Some produce neurotoxins

          • Exposed through shellfish

          • Saxitoxin

  • Rhizaria

  • Amoebozoa

    • Lobe-shaped Pseudopods

    • Most lack flagella

    • Phagocytosis

    • Some man pathogens

      • Naegleria

        • Causes amebic meningoencephalitis

      • Acanthamoeba

        • Causes blindness

      • Entamoeba

        • Causes acute dysentery, colitis and long-term chronic diarrhea

    • Slime molds

      • 2 types:

        • Plasmodial

        • Cellular

Fungi:

• Chemoheterotrophic

  • Most exist as saprobes

    • They absorb nutrients from dead organisms

• Function as major decomposes of organic matter

• More than 100,000 species

  • Classified in 3 divisions

    • Zygomaycota

    • Ascomycota

    • Basidiomycota

  • 200 or less have demonstrated to cause disease in humans

• Have cell walls

  • Composed of Chitin

• Do NOT perform photosynthesis

• Lack chlorophyll

• 2 types:

  • Yeasts

    • Grow as single cells that reproduce through asexual budding

  • Molds

    • Grow as long filaments (hyphae)

      • Some form transverse walls

        • Septate hyphae

      • Others do not form walls

        • Non-septate hyphae

• Some fungi produce yeast-like and mold-like shapes and are called Dimorphic

  • Change their growth habits based on the temp of their immediate vicinity

• Many are obligate aerobes

• Some are facultative anaerobes

• Recognize the fungus and its common clinical diseases

• Nutrition

  • Saprobes

    • Absorb form dead organisms

  • Haustoria

    • Trap and kill microscopic soil-dwelling nematodes

• Reproduction

  • Budding and asexual spore formation

  • Sexual spore formation

• Classification

  • Zygomycota

    • Most re saprobes

    • Asexual

    • Obligate intracellular parasites

    • Spread small, resistant spores

  • Ascomycota

    • Sexual spores

    • Asexual also

    • Most of the fungi that spoil food

    • Infect plants and humans

    • Beneficial for drug manufacturing

      • Penicillium

      • Saccharomyces

  • Basidiomycota

    • Above ground mushrooms

    • Fruiting body contains sexual spores

    • May produce toxins or hallucinatory chemicals

      • Death cap mushroom

      • Toadstools

  • Deuteromycetes

    • Imperfect fungi

    • Asexual

Parasitic Helminths (worms)

• many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract

• Others (schistosomes) reside in blood vessels

Arthropod Vectors

• Arachnida

  • 4 pairs of legs

  • Ticks (most common)

  • Mites

• Insecta

  • 3 pairs of legs

  • Mosquitos

  • Fleas

Vector-borne parasites:

• Kissing bug

  •Trypanosoma

• Mosquito

  •Plasmodium

  •Wuchereria

• Sand fly

  •Leishmania

• Tsetse fly

  •Trypanosoma