1. Every form of life either is a single cell or is composed of cells, each of which can arise only from another cell. 2. The two most fundamentally different kind of cells are eukaryotic cells, each of which has its primary complement of DNA enclosed inside a membrane-lined nucleus: and prokaryotic cells, whose DNA is not enclosed within this structure. 3. In a eukaryotic cell, the cytoplasm is the region that lies inside the plasma membrane but outside the nucleus. The jelly-like fluid filling much of this region is called the cytosol, while the individual highly organized structures within it are called organelles.
Chapter 4 - Pg. 76
1. The cell’s nucleus holds the cell’s primary complement of DNA, which contains information for the production of proteins. 2. Proteins of the sort followed in the text are put together within tiny organelles called ribosomes that lie outside of the nucleus. During their production, these proteins fold up upon entering the RER, where they undergo editing, after which they move to the gorgi complex, where they undergo further editing and are sorted for distribution. 3. Proteins and other materials move through the cell within membrane-lined spheres called transport vesicles, which, together with membrane-lined organelles, make up the endomembrane system.
Chapter 4 - Pg 83
1. Lipids, including fats, are put together in the organelle called the smooth ER, while worn-out cellular materials are broken down and recycled in the organelles called lysosomes. 2. The organelles called mitochondria transform the energy from food into a usable chemical form, contained in a molecule called ATP. 3. The cell’s internal scaffolding, made up of different types of protein fibers, is called the cytoskeleton.
Chapter 4 - Pg 87
1. Plant cells have two organelles and one structure that animal cells do not have. The organelles are chloroplasts, which are the sites of photosynthesis, and a large central vacuole, which performs multiple functions, including the storage of nutrients and the maintenance of internal cell pressure. The structure is the cell wall, which provides protection and limits the plant cell’s uptake of water. 2. Animal cells have only a single organelle that plant cells do not have. This is the lysosome, which breaks down and recycles materials in the cell. 3. In plants, the channels that facilitate cell-to-cell communication are called plasmodesmata, while in animals, the tube-like protein structures that facilitate such communication are called gap junctions.