Cells

3. the positively charged central core of an atom, consisting of protons and neutrons and containing nearly all its mass.
5. a rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. In the algae and higher plants it consists mainly of cellulose.
7. a minute particle consisting of RNA and associated proteins found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins.
10. (in green plant cells) a plastid that contains chlorophyll and in which photosynthesis takes place.
12. a complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells, involved in secretion and intracellular transport.

1. a large, dynamic structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism.
2. a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.
4. It is composed of water, salts, and various organic molecules. Some intracellular organelles, such the nucleus and mitochondria, are enclosed by membranes that separate them from the cytoplasm.
5. the semipermeable membrane surrounding the cytoplasm of a cell.
6. an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner layer being folded inward to form layers (cristae).
8. a membrane-bound cell organelle that contains digestive enzymes.
9. a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
11. green plant cells) a plastid that contains chlorophyll and in which photosynthesis takes place.