All animals have eukaryotic cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules. During development, it forms a relatively flexible framework upon which cells can move about and be reorganized, making complex structures possible. In contrast, other multicellular organisms, like plants and fungi, have cells held in place by cell walls, and so develop by progressive growth. Also, unique to animal cells are the following intercellular junctions: tight junctions, gap junctions, and desmosomes. COUNT 5
QSN1 What type of cells do all animals have? ANS1 eukaryotic QSN2 What is the extracellular matrix surrounding eukaryotic cells made of? ANS2 collagen and elastic glycoproteins QSN3 What is formed when the collagen and elastic glycoproteins surrounding eukaryotic cells are calcified?  ANS3 shells, bones, and spicules QSN4 What are the intercellular junctions unique to animal cells? ANS4 tight junctions, gap junctions, and desmosomes QSN5 How are cells held in place in plants and fungi? ANS5 cell walls