Chapter 26 - 28 Flashcards

Evolution of metabolism

Glycolisis → proton pump → ETC + chemiosmosis → photosynthesis splitting H2S → photosynthesis evolving O2 → aerobic cellular respiration

Cause of mass extinctions

Volcano, Asteroid, Climate Change, Natural Disasters

6th mass extinction

Caused by humans accelerating climate change

States of chemical evolution of life

1) abiotic synthesis + accumulation of small organic molecules (monomers) like amino acids

2) joining of these into polymers, including proteins + nucleic acids

3) aggregation of abiotically produced molecules into droplets, protobionts that hold chemical characteristics different from their surroundings

4) origin of heredity (maybe before the droplet stage)

Characteristics of the first organism

Prokaryote, asexual, anaerobic, nutrition chemoheterotrophic (oxidates (losing electrons) organic compounds)

3 domains of life

Bacteria, Archea, Eukarya

Supporting evidence for three domains of life

Bacteria the only ones with peptidoglycan, archea and eukarya both us Met for START in proteins synthesis, both bacteria and archea have a circular chromosome.

Archea is more closely related to Eukarya than bacteria.

Bacterial shapes

Coccus - spherical

Bacillus - rod shaped

Spirillum - spiral shaped

Genophore

The prokaryotic chromosome, single and circular

Gram - vs. Gram +

+ has more peptidoglycan and a simpler wall, stains purple

-has less peptidoglycan but a more complex cell wall, stains red/pink

Means of locomotion in prokaryotes

• Axial filaments (bundles of fine fibrils)

• Slime

• Flagella

Taxis

Movement towards/away from stimulus (directed movement)

Repreoduction in prokaryotes

• Binary fission (asexual)

• Conjugation (sexual - sex pilus)

• Transduction (sexual - virus carries DNA to another cell)

Metabolism types

• Autotroph

  • Chemoautotroph - energy source is inorganic chemicals, carbon source is CO2 (ONLY IN SOME BACTERIA)

  • Photoautotroph - energy source is light, carbon source is CO2 (PLANTS, BACTERIA, PROTISTS)

• Heterotrophic

  • Chemoheterotrophic - obtains both energy and carbon from organic compounds (ANIMALS AND BACTERIA)

  • Photoheterotrophic - obtains energy from light and organic compounds as source of carbon(SOME WEIRD BACTERIA)

Heterocysts

Specialized nitrogen-fixing cells found in certain cyanobacteria that facilitate the conversion of atmospheric nitrogen into ammonia, providing a source of nitrogen for the organism.

Enteric bacteria

A group of bacteria that reside in the intestinal tracts of humans and animals, including pathogenic strains such as Escherichia coli (E. coli) and Salmonella, often associated with gastrointestinal diseases.

Endo vs. Exotoxins

• Exotoxins - produces specific symptoms, proteins secreted by bacterial cells

• Endotoxins - components of outer membranes of Gram - bacteria, produces aches and fever

Koch’s postulates

Connecting a specific bacteria to a specific disease. The four postulates are: 1) The microorganism should be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms. 2) The microorganism must be isolated from a diseased organism and grown in pure culture. 3) The cultured microorganism should cause disease when introduced into a healthy organism. 4) The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

Characteristics of Archeabacteria

• cell walls lack peptidoglycan

• Lipid cell membrane + unique enzymes

• Methanogens, Halophiles, Thermoacidophiles

Methanogens

Microorganisms that produce methane as a metabolic byproduct in anoxic conditions. They are a type of archaea found in diverse environments, including wetlands and the digestive tracts of ruminants. Methanogens play a key role in the carbon cycle by decomposing organic matter.

Halophiles

Organisms that thrive in high-salinity environments, often found in salt lakes and salt mines, characterized by specialized adaptations to survive osmotic pressure.

Thermoacidophiles

Microorganisms that thrive in both high temperatures and acidic environments, often found in hot springs and geothermal areas. They are a type of extremophile that can survive in harsh conditions.

Importance of prokaryotes

1. Decomposers (can recycle for ecosystems ex: cleaning oil spills!)

2. Fix N2 + CO2, generate O2

3. Symbiotic relationships

4. Pathogens (opportunistic)

Can be used to make food, antibiotics.

Symbioses in prokaryotes

• Mutualism - both benefit

  • Ex: bacteria in legume roots for N2 fixatioN, vaginal bacteria regulating pH

• Commensalism - symbiont benefits, host unaffected

  • Ex: bacteria on the skin like Staph

• Parasitism - symbiont benefits at host’s expense

  • Ex: most pathogens

Endosymbiont theory

How the first eukaryotic cell came about, larger prokaryote engulfed a smaller aerobic prokaryote, lived symbiotically, became so dependent couldn’t live independently anymore, thus became mitochondria. Smaller photoautotrophic bacteria engulfed and became chloroplasts.

Supporting evidence of endosymbiont theory

1. Double membrane

2. Mitochondria and chloroplasts the size of typical prokaryotes

3. Have their own ring DNA like prokaryotes

4. Have their own ribosomes which are more similar to prokaryotes

5. Both can do binary fission

Characteristics of protists

• They’re all eukaryotic

• Protozoans (ancestors of animals), Algal protists (ancestors of plants), Fungus like protists (ancestors of fungi)

Characteristics of protozoans (Makes them similar to animals)

• nutrition by ingestion

• Locomotion

• No cell walls

Characteristics of algal protists (what makes them plant-like)

• Similar pigments

• Have cell walls

• Photoautotrophic

Characteristics of fungus-like protists

• fungus way of reproducing (stalks)

• Decomposers, chemoheterotrophic

Diversity of protists

• Protozoans are classified by locomotion

  • Ex: Rhizopoda use pseudopods, Ciliophora use cilia, Apicomplexa use no locomotion, Zoomastigina uses flagella

• Algae classified by cell wall components

  • Ex: chlorophyta uses cellulose

Alternation of generations (During lifecycles)

Haploid becomes diploid, meiosis to half diploid back to haploid

Importance of protists

• Some are producers (creating oxygen)

• Symbiotic relationships (Ex: termites)

• Decomposers

• Diseases

• Diatoms used in toothpaste or cleaning products, diatomaceous earth or swimming pool filters

• Seaweed in foods, some algae used to make agar

Cyanobacteria

• photoautotrophs

• may be filamentous

• motile forms glide

• live in freshwater, saltwater, and damp soil

• chlorophyll A in thylakoids

• heterocysts in some useful for N2 fixation

phototrophic bacteria

• green + purple sulfur

• get electrons from H2S

• pigment in bacterioentorophyll

• usually anaerobic

Pseudomonads

• soil, aquatic

• most versatile chemoheterotrophs

spirochetes

• helical shaped; corkcscrew movement

• large cells

• saprophytic (dead host) or parasitic

Example of a spirochete

Treponema pallidum, which causes syphillis

Endospore forming bacteria

• produce spores - dehydrated cells with thick walls

• autoclave necessary to kill spores up to 120 degrees Celcius

Example of endospore forming bacteria

Clostridium botulinum causes botulism

Rickettsias + Chlamidias

very small (dependent parasites) Ex. Chlamidia

Mycoplasmas

smaller than rickettsias, ONLY PROKARYOTES LACKING CELL WALLS

Actinomycetes

• colonial, resembling fungal bodies

• causes TB + leprosy

• “dirt smell” in soil

Myxobacteria

• gliding bacteria

• elaborate colonies

• erects bulbous stalk (fruiting body)

• spore producing

• brightly colored

phylum Chlorophyta

• green algae

• unicellular, colonial or multicelluar

• 2 or more flagella

• cellulose cell walls

phylum Acrasiomycota

• cellular slime molds

• ameboid unicellular + multicellular stages

• terrestrial heterotrophs

• decomposers

• ex: Dictiyostelium