eukaryotes and prokaryotes

Define Prokaryote and Eukaryote and identify which kingdoms belong to each.

Back: * Prokaryotes: Simple cells lacking a nucleus or membrane-bound organelles (e.g., Bacteria and Archaea).

​Eukaryotes: Complex cells containing a distinct nucleus and membrane-bound organelles (e.g., Animals, Plants, Fungi, and Protists).

​Grade 8 Tip: Remember that "prokaryote" literally means "before nucleus."

Front: Contrast how DNA is stored in a bacterial cell versus an animal cell.

Back: * Eukaryotes: DNA is linear, associated with proteins (histones), and enclosed within a double-membrane envelope (the nucleus).

​Prokaryotes: Genetic material consists of a single circular strand of DNA that floats freely in the cytoplasm (nucleoid region). They also contain plasmids—small loops of extra-genomic DNA.

Front: Which cell types possess a cell wall, and what are they made of in each kingdom?

​Prokaryotes (Bacteria): Almost all have a cell wall made of peptidoglycan (murein).

​Eukaryotes (Plants): Made of cellulose.

​Eukaryotes (Fungi): Made of chitin.

​Eukaryotes (Animals): No cell wall present.

Front: Compare the size and internal structures (ribosomes/organelles) of prokaryotes and eukaryotes.

Back:

​Size: Prokaryotes are much smaller (0.1\text{ to }5.0\,\mu\text{m}) compared to eukaryotes (10\text{ to }100\,\mu\text{m}).

​Ribosomes: Eukaryotes have larger 80S ribosomes; Prokaryotes have smaller 70S ribosomes.

​Organelles: Eukaryotes have mitochondria and chloroplasts; prokaryotes lack these, often using their cell membrane for metabolic reactions

Front: Explain the significance of plasmids and the method of reproduction in prokaryotes.

Plasmids: Small, circular DNA molecules that can replicate independently and often carry genes for antibiotic resistance. They can be transferred between bacteria (conjugation).

​Reproduction: Prokaryotes divide via binary fission (asexual), whereas eukaryotic cells divide via mitosis or meiosis.