eukaryotic cells

a cell which contains a nucleus and other membrane bound organelles - makes up multicellular organisms

• nuclear pores allow movement of molecules e.g. mRNA • double membrane called nuclear envelope

• contains genetic info (DNA) which directs protein synthesis • DNA associates with histone proteins to form chromatin which prevents the DNA getting tangled • controls metabolic processes

• within nucleus • produces ribosomes • made of proteins and RNA

• double membrane • inner membrane folded to form cristae • fluid interior = matrix • contains mitochondrial DNA

• respiration occurs • energy is stored in bonds of organic molecules • cristae has an increased surface area for respiration • contains enzymes • produces ATP

• membranous sacs for storage and transport made of phospholipid bilayer • contains fluid

• specialised vesicles • contains hydrolytic enzymes • breaks down waste and pathogens • important in immune system

microfilaments microtubules intermediate fibres

• contractile fibres • formed from actin protein • movement and contraction during cytokinesis

• globular tublin proteins • polymerise to form tubes • acts like scaffold structure • holds shape and allows movement • composes spindle fibres

• mechanical strength • maintains integrity

• mechanical strength • allows movement of organelles • holds shape • important in composition of spindle fibres and cytokinesis

• network of membranes • flattened sacs called cisternae • connected to nucleus

lipid and carbohydrate synthesis and storage

protein synthesis and transport

• free in cytoplasm or attached to rough ER • not membrane bound • exits nucleus via pores • constructed of rRNA and proteins • site of protein synthesis

• network of membranes • compact • formed from cisternae • modifies proteins • packages proteins into vesicles

• part of cytoskeleton • composed of microtubules • 2 centrioles form centrosome in organising spindle fibres

• whip like structure • enables cell movement • detects chemical change in cell’s environment

• hair like structure • stationary = present on cell surface in sensory organs • mobile = creates a current to move fluid/objects adjacent to cell • each cilium contains 9 + 2 microtubules where parallel pairs slide over each other to create a beating motion

• composed of lipids and proteins • regulates movement of substances in and out • receptor molecules allow it to respond to chemicals

• depends on actin filament activity • filament lengths change when subunits are added • subunits change shape before being added to the minus end of the filament • subunit concentration in cytoplasm determine whether they are added to the filament

• surrounds cell surface membrane • keeps cell rigid • freely permeable • protects against pathogens