Prokaryotes 🦠 are much smaller without nucleus, cytoskeleton and membrane surrounded organelles. Their DNA transcription occurs simultaneously with protein synthesis.

Gram-positive bacteria 🦠 containing more peptidoglycan are stained purple, while negative bacteria with more lipopolysaccharide appear red or pink.

How are archaea discovered? 🦠Archaea vs bacteria: cell membrane is protein, cell wall is an ether compound, glucose is utilized by modified glycolysis, and the genome is like eukaryotes.

Methanogens without glycolysis are extremely anaerobic. Halophilic archaea live in high-salt water. Rhodopsin absorbs photons to make ATP. Thermophile contribute heat-stable enzymes to PCR.

The virus consists of nucleic acid, capsid, envelope and spiked protein. They usually range from 20 nm to 200 nm. They come in various shapes: rod, icosahedral, filamentous, spherical.

A sponge is a member of the phylum Porifera. It is a simplest oldest multicellular animal, but no mouth, muscles, heart or brain. It is sessile filter feeder and locate in hard substrate permanently.

Cyanobacteria, also known as blue-green algae. Their symbiosis with other organisms, photosynthesis and nitrogen fixation play an important role in modifying the Earth's ecosystem and influencing the evolution of life.

Chlamydia parasitically reproduces in the host. They are transmitted through sexual contact, skin contact, and respiratory droplets. They cause diseases of the urinary and reproductive systems and also cause pneumonia and conjunctivitis in humans. Macrolide antibiotics can treat these diseases.

Mycoplasma is the smallest cell that can survive on its own. They do not have a cell wall and their plasma membrane is rich in sterols. They can also be parasitic within cells. They require nutrient-rich media or live cells to be cultured.