Complex eukaryotic cell evolved when prokaryotes took up residence within larger prokaryotes. Protists are the most nutritionally diverse of all eukaryotes. Some of them are photoautotrophs, containing chloroplasts. Some are heterotrophs, absorbing organic molecules or ingesting larger food particles. Still others, called mixotrophs, combine photosynthesis and heterotrophic nutrition. Protists also can be divided by habitats.
WHAT ARE THE DIFFERENCES BETWEEN BACTERIA AND ARCHAEA?
Archaea: cell membrane contains ether linkages; cell wall lacks peptidoglycan; genes and enzymes behave more like Eukaryotes; have three RNA polymerases like eukaryotes; and extremophiles
Bacteria: cell membrane contains ester bonds; cell wall made of peptidoglycan; have only one RNA polymerase; react to antibiotics in a different way than archea do.
WHAT MAKES THE PROTISTS ANCESTOR OF EUKARYOTES?
Kingdom protista consists of the single-celled eukaryotes as well as a variety of not very morphologically complex multicellular eukaryotes. All protists are eukaryotes, but protists are so diverse that few other general characteristics can be cited without exception. In fact, protists vary in structure and function more than any other group of organisms at the cellular level, many protists are exceedingly complex the most elaborate of all cells. We should expect this of organisms that must carry out within the boundaries of a single cell all the basic functions performed by the collective of specialized cells that makes up the bodies of plants and animals.
SUMMARY:
Prokaryotes have lived way longer than eukaryotes. They live in cold, hot, salty, acidic, and alkaline habitats. Although some bacteria are pathogenic and cause disease, most on our bodies are benign or beneficial. There are two prokaryotic domains, bacteria and archaea, diverged soon after life on Earth arose. Prokaryotic cell walls maintain cell shape, provide physical protection, and prevent the cell from bursting in a hypotonic environment. Some prokaryotes stick to the substrate or each other with pili.P Prokaryotic DNA forms a circular chromosome. Smaller rings of DNA called plasmids carry genes that may provide resistance to antibiotics or metabolize rare nutrients, among other metabolic activities Many prokaryotes can transfer genes, such as antibiotic resistance genes, within or between species.Pathogenic bacteria cause disease by producing poisonous exotoxins or endotoxins. Endotoxins produce septic shock, bacterial meningitis, and food poisoning.
Protists constitute several kingdoms within the domain eukarya. They obtain their nutrition in a variety of ways: algae are autotrophic protists. Protozoans are heterotrophic, eating bacteria and other protists. Fungus-like protists obtain organic molecules by absorption. Protists are eukaryotes, with membrane-bound chromosomes, multiple chromosomes, and flagella or cilia with 9+2 pattern of microtubules. Euglenozoans are diverse clade of protists. their common feature is a crystalline rod of unknown function inside their flagella. Amoebas move and feed by pseudopodia. Members of the clade amoebozoans include many free-living amoebas, soma parasitic amoebas, and slime molds. Foraminiferans and radiolarians move and feed by means of threadlike pseudopodia. Red algae are typically soft bodied, but some have cell walls encrusted with hard, chalky deposits. Green algae split into two groups, the chlorophytes and the charophytes.
KEY TERMS:
- Exotoxins: proteins secreted by bacterial cells
- Endotoxins: components of the outer membrane of gram-negative bacteria, released when the cell dies or is digested by a defensive cell
- Symbiosis: close association between organisms of two or more species
- Diplomonads: possibly the most ancient surviving lineage of eukaryotes
- Parabasalids: heterotrophic protists with modified mitochondria that generate some energy anaerobically
- Alvelates: have membrane-enclosed sacs or alveoli beneath the plasma membrane
- Dinoflagellates: important members of marine and fresh water phytoplankton
- Ciliates: use cilia to provide moments and feed
- Apicomplexans: animal parasites such as plasmodium, which causes malaria
- Foraminiferan: live in marine and freshwater. They have porous tests with small pores through which pseudopodia extend
Ciliates (csillósok)
-covered with cilia, move by beating cilia
-have 2 kinds of nuclei: macronucleus to control cell life functions and micronucleus (1 or more) for reproduction
eg. Paramecium (papucsállatka)
5 FACTS:
1) Prokaryotes are diverse and widespread
2) Prokaryotes are origin of eukaryotes
3) Various structural features contribute to the success of prokaryotes
4) Diplomonads and parabasalids have modified mitochondria
5) Amoebozoans have lobe-shaped pseudopodia
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