2.2

• Prokaryotic and eukaryotic cells have many features in common, reflecting their common evolutionary past
• Prokaryotes lack internal membrane-bound organelles and a nucleus
• Prokaryotes are significantly smaller than eukaryotes and usually have a single circular chromosome
• Prokaryotes are unicellular
• Eukaryotic cells are multicellular
• Eukaryotic cells are 100 to 10,000 times larger than prokaryotic cells
• Eukaryotic cells store DNA in the nucleus
• Eukaryotic cells have double-stranded DNA wrapped around histone proteins and condensed to form 46 chromosomes
• Eukaryotic cells have membrane-bound organelles
• Prokaryotic cells are very small, ranging from 1-10µm in length to 0.2-2.0 µm in diameter
• Prokaryotic cells have DNA that floats freely in the cytoplasm
• Prokaryotic cells have a single circular chromosome and extra bits of DNA in the form of small circular plasmids
• Prokaryotes are grouped with two domains: bacteria and archaea
• Prokaryotes lack membrane-bound organelles, limiting the versatility of simple cells
• Cytoplasm in prokaryotes surrounds the internal structures of the cell and maintains an optimal environment for other organelles
• Ribosomes are not organelles; they are composed of RNA + proteins and function in protein synthesis
• Eukaryotic cells are found in the kingdoms: animals, plants, fungi, and protists
• Organelles are structures bound by a membrane with specialist functions
• The nucleus in eukaryotic cells controls and regulates cell activities and carries genes
• The nucleus in eukaryotic cells stores DNA as double-stranded DNA wrapped around histone proteins and condensed to form 46 chromosomes
• Cytoplasm suspends organelles in place and maintains an optimal environment
• Cytosol is the semi-fluid part of the cytoplasm not including organelles and is where metabolic activity occurs
• Centrosomes have a major role in cell division and are located close to the nucleus
• Centrioles are involved in cell division and the formation of cell structures like flagella and cilia
• Chloroplasts in plant cells are the site of photosynthesis
• Cell walls in plant cells protect the cell, maintain its shape, and prevent excessive water uptake
• Large vacuoles in plant cells store substances and are involved in cell structure
• Organelles that facilitate waste transport include endoplasmic reticulum, Golgi apparatus, lysosomes, and cell membrane
• The rough endoplasmic reticulum processes and modifies proteins and is a site for protein synthesis
• The smooth endoplasmic reticulum transports proteins, synthesizes lipids, and assists in manufacturing cell membranes
• The Golgi apparatus collects, packages, modifies, and distributes materials like proteins in the cell
• Lysosomes are sacs of enzymes that digest foreign substances and macromolecules
• The cell membrane controls the entry and exit of substances and encloses the cell
• Exocytosis is the movement of molecules out of the cell, while endocytosis is the movement of molecules into the cell