CELL AS A BASIC UNIT CELL SIZE AND SHAPE INTRODUCTION A cell is the smallest unit of a living thing and is the basic building block of all organisms A living thing whether made of one cell like bacteria or many cells like a human is called an organism Thus cells are the basic building blocks of all organisms Several cells of one kind that interconnect with each other and perform a shared function form tissues Several tissues combine to form an organ your stomach heart or brain and several organs make up an organ system such as the digestive system circulatory system or nervous system SKASC 2 Cell Theory SKASC 3 Traits of Prokaryotes They do not have a nucleus and their genetic material is not stored in the nucleus They have some organelles structures but not many They are less complicated that eukaryotes All bacteria are prokaryotes Most are unicellular but some prokaryotes are multicellula SKASC 4 SKASC 5 Cell Wall The Walls Cell walls are rigid and unbending SKASC 6 Ribosomes Structure rRNA Proteins Function Site of protein formation translation Found in both prokaryotes and eukaryotes different structurally SKASC 7 Cytoplasm The Jelly in the centre The cytoplasm in the cell is jelly like liquid that fills all the empty space in a cell SKASC 8 The protoplasm or cytoplasm The dense gelatinous solution within the cell membrane that is the primary site for the cell s biochemical and synthetic processes The following are found within the protoplasm of the prokaryotic cell SKASC 9 Vacuole The vacuoles are the cell s storage place where it keeps water food and waste SKASC 10 Genetic Material DNA The genetic material DNA is stored in the nucleus and holds information a cell needs to reproduce itself SKASC 11 Nucleus Structure and Function membrane similar to cell membrane similar function Nucleolus formation of ribosomes Chromosomes gene expression Nucleoplasm matrix Lysosomes Structure membrane bound sac containing hydrolytic enzymes Function digestion SKASC 12 SKASC 13 Cell Size SKASC 14 Limits to cell size Lower limit Smallest bacteria Mycoplasmas 0 1 to 1 0 micron m micrometer Most bacteria 1 10 microns Upper limit SKASC 15 Eukaryotic cells 10 100 microns What limits cell size Surface to volume ratio as cell gets bigger its volume increases faster than its surfac smaller objects have greater ratio of surface area to volume SKASC 16 Cell membrane Exchange structure Plasma membrane functions as selective barrier Allows passage of O2 nutrients IN Allows passage of products wastes OUT SKASC 17 Cellular Organization 1 Nucleolus 2 Nucleus 3 Ribosomes 4 Vesicles 5 Rough ER 6 Golgi apparatus 7 Cytoskeleton 8 Smooth ER 9 Mitochondrion 10 Vacuoles 11 Cytosol 12 Lysosome 13 Centriole 14 Cell Membrane SKASC 18 What is Cellular Organization By definition cellular organization is the components that make up the cell and how they are arranged inside it Each component called an organelle performs a specific function that is vital for the cell SKASC 19