7 All cells share certain characteristics. All cells are enclosed by a membrane.All cells are filled with cytoplasm.All cells have DNA.All cells have ribosomes.cell membraneBacterium(colored SEM; magnification 8800x)cytoplasm
8 There are two cell types: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus.Eukaryotic cells have membrane-bound organelles.nucleusorganellescell membrane
9 Prokaryotic cells do not have a nucleus. Prokaryotic cells do not have membrane-bound organelles.nucleusorganellescell membranecytoplasm
19 Ribosomes link amino acids to form proteins. Vesicles are membrane-bound sacs that hold materials.Vesicles help maintain homeostasis by storing and releasing a variety of substances as the cell needs them.
21 Protein Processing Making and Exporting Proteins The ribosomes located on the rough ER make proteins which then cross into the membranes of the ER. The ER membrane then pinches off and forms a vesicle around the proteins.Vesicles transport the proteins from the rough ER to the Golgi apparatus, where they are modified by enzymes and repackaged in new vesicles.These new vesicles transport the modified proteins to the cell membrane to be released outside the cell.
23 LysosomesA lysosome is a vesicle produced by the Golgi apparatus that contains enzymes that break down large molecules.Lysosomes recycle old or damaged organelles and digest food particles to provide nutrients for the cell.