* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CELLS AND CELL STRUCTURE Biology and Geology IES El Escorial April 2021 CELLS: THE BUILDING BLOCKS OF LIFE • All living things, as well as having the same kinds of molecules, are made up of the same basic structures: cells. • Cells are the building blocks of life. • Cells are divided into two classifications: prokaryotic and eukaryotic cells. EUKARYOTIC CELL STRUCTURE • All cells, may it be prokaryotic or eukaryotic, have three similar structures, they have: • Cytoplasm • Cell membrane or plasma membrane • Nucleus • Eukaryotic cells can either be animal or plant cells. ANIMAL CELL STRUCTURE • Animal cells come in many different shapes and sizes, although they are usually more or less spherical. • Animal cells have cell membranes which are semipermeable structures which allow selected substances to enter the cell. • They also have vacuoles which contain substances such as food and waste materials. • They have mitochondria which are the energy centres of the cell. This is where cell respiration takes place. • They also have a nucleus, which contains the cell’s DNA. PLANT CELL STRUCTURE • Plant cells are larger than animal cells. • They come in different sizes but they are normally polyhedral. • Unlike animal cells, they have a cell wall, which is a thick, rigid layer, made of cellulose that maintains the cell’s form. • They also have larger vacuoles, and these fluid-filled cavities occupy most of the cytoplasm. • They also have chloroplasts, which enables photosynthesis to occur.