Diversity of Life Flashcards
Gram-positive bacteria
- Stain dark purple
- Thick peptidoglycan layer in cell wall
- No outer (second) membrane
- Relatively small periplasm
- No (endotoxins) lipopolycaccharide (LPS)
- Secrete exotoxins
- Contain teichoic acids (acidic polysaccharide connecting peptidoglycan layer and plasma membrane for rigidity and structure
Gram-negative bacteria:
- Stain pink (due to counterstain)
- Thin peptidoglycan layer in the cell wall
- Contains periplasm between inner and outer membrane
- Outer (second) membrane present
- LPS present (an endotoxin release when bacteria is destroyed)
- Secrete exotoxins
- No teichoic acids
Cell wall of archea
No peptidoglycan present in cell wall, instead they contain some pseudomurein (a molecule that is analogous to peptidoglycan but with different peptide cross bridges)
Cell walls are also composed of sugars, proteins and inorganic molecules
Cell wall of eubacteria
Peptidoglycan present (a carbohydrate and protein polymer), encompassing the entire bacterial cell wall and allows for anchoring
The peptide and carbohydrate cross bridge linkages have D-amino acids that provide structural integrity
DNA organization of archea
- Circular
- Utilize histones and introns
DNA organization in eubacteria
- Circular
- Lack histones and introns
Endospores
- Produced by some bacteria
- A tough, non-reproductive structure that allows bacteria to enter a dormant state
- In the dormant state, the cell’s genetic material is preserved, allowing the cell to survive during times of extreme environmental stress
Fungus-like protists
- Lack a cell wall made of chitin
- Can move with flagella and cilia
- Saprophytic: feed on decaying matter
- Most live in moist soil
- Ingest food via phagocytosis
- Asexual reproduction and sporulation (spores produced have thick and strong cell walls allowing to resist environmental conditions
Plant-like protists
(algae-like protists)
* Among the most important primary consumers
* Photosynthetic autotrophs: produce organic matter from inorganic molecules using photosynthesis
* Examples: diatoms, euglenoids and dinoflagellates —> unicellular, photosynthetic autotrophs that reproduce asexually and are found in aquatic environments
Dinoflagellates
Responsible for red tide (toxins build up, oxygen in water is depleted)
Posses 2 flagella (find food in the absence of light)
Can parasitically infect certain animals (heterotrophic)
Animal-like protists
- Known as protozoa
- Eukaryotic (membrane-bound organelles)
- Unicellular
- Heterotrophic
- Move via flagella and cilia
- Often parasitic pathogens that infect and feed off a host organism (consume living cells or dead organic matter
- Contain food vacuole to store food
- Ingest food via phagocytosis
Kingdom fungi key features
- Heterotrophic sporophytes: feed on decaying/dead matter
- Posses a cell wall contain the polysaccharide glucan
- Have a predominantly haploid life cycle
Nonfilamentous fungi
- Yeast
- unicellular
- Reproduce asexually by budding
- Facultatively anaerobic: utilize fermentation in absence of oxygen to convert glucose to carbon dioxide and ethanol
Filamentous fungi
- Molds
- Multicellular and multinucleate
- Undergo aerobic respiration (require oxygen to gain energy from food)
- Reproduce sexually
- Form hyphae
Hyphae
Long, branching filaments that extend out to form a network of fungi (mycelium) with nearby fungi
› Collectivley all the hyphae are known as mycelium, which includes all connected spores
Septate hyphae
- Have septum dividing hyphae into multiple sections/compartments
- Causes the mycelium to look segmented
- Cell division occurs with cytokinesis which generates the individual septa as the cell grows
- Each compartment has a single nucleus
- Septa can close if injured and septa increases structural stability
Coenocytic hyphae
No septa present
One long continuous multinucleate cell (coenocyte)
Cell division occurs without cytokinesis
No septa allows for rapid nutrient diffusion
Phylum Platyhelminthes general characteristics and examples
- Reproduce sexually (hermaphrodites) or asexually (regeneration)
- Mainly aquatic habitats
- Parasitic lifestyle
- Most primitive of triploblasts
- Have organs
- Ex: tapeworms, flukes, planarian and flatworms (The Flat Planet Failed)
Phylum platyhelminthes body symmetry
Bilateral symmetry (can be split into equal right and left halves down the mid-sagittal plane) with cephalization (concentration of nervous/central organs in the brain/head)
Phylum Platyhelminthes tissue organization
Triploblastic (derived from three embryonic germ layers)
Eumetazoa
Phylum Platyhelminthes digestive system:
Gastrovascular cavity (one opening with two way digestion), except for tapeworms (they absorb food from surroundings)
Use a combination of extracellular (enzymes secreted into gastrovascular cavity, food particles breakdown) and intracellular (food particles engulfed and digested in food vacuoles) digestion
Phylum Platyhelminthes circulatory system
None- diffusion
Phylum Platyhelminthes respiratory system
None- diffusion
Phylum Platyhelminthes nervous system
Utilize two nerve cords (dense nerve bundle running along the length of invertebrates) and anterior centralized ganglia (brain)
Some planarians have eyespots