Structure and function of cell components (i)Carbohydrates (ii)Lipids (iii)Proteins (iv)Nucleic Acids (v)Membranes (vi)Cytoskeleton

Structure of cytoskeleton Cytoskeleton is found in all eukaryote cells It is anchored in the cell membrane via membrane proteins It is composed of 3 types of fibre microfilaments

Microtubules Found in all eukaryote cells Hollow tubes made of the protein tubulin Radiate from the MTOC (microtubule organising centre), stretch to plasma membrane MTOC changes length of microtubule by assembling and disassembly ends Microtubules can be assembled and disassembled rapidly Components of microtubules become spindle fibres during cell division

Microtubules cont…. Function Provide structural support by resisting compression Provide structural support by resisting compression Have a role in organelle movement Have a role in organelle movement Separate chromatids during cell division Separate chromatids during cell division Components of cilia, flagella and centrioles Components of cilia, flagella and centrioles

Microfilaments Made of actin protein Present throughout the cell, but most common just inside the plasma membrane Readily assembled and disassembled Function Involved in cell membrane movements e.g. Endocytosis / Phagocytosis Involved in cell membrane movements e.g. Endocytosis / Phagocytosis Give cell shape Give cell shape Are part of the contractile ring that forms the two daughter cells during cytokinesis of animal cells Are part of the contractile ring that forms the two daughter cells during cytokinesis of animal cells

Intermediate filaments Mostly made of keratin proteins Not found in all cells Probably permanent (cannot be assembled and disassembled) although cells may be able to regulate length Function Very stable tough fibres providing cell support Very stable tough fibres providing cell support Abundant in areas of a cell subject to mechanical stress Abundant in areas of a cell subject to mechanical stress

Learning Activities Read and take notes from DART pg (58- 60) Scholar 5.3 Look back at the role of MTOCs and spindle fibres in cell division (cell cycle notes) Create a list of cytoskeleton functions and remember it Advanced Higher Questions