Cell Structure

Plasma membrane Function Structure Main component is phospholipids that are arranged in a double layer (bilayer) Has scattered proteins within the phospholipids Function Regulate what enters/leaves cell

Nucleus Structure Function Surrounded by a double membrane Membrane contains pores (holes) to allow RNA to leave Function Holds the chromosomes (chromatin)…DNA and the nucleolus

Nucleolus Structure Function Small dark structure in the nucleus Produce ribosomes

Ribosomes Make proteins Small structures (NOT made of membrane) Free stay in cytoplasm Bound Secreted (released) Inserted in membranes Packaged into other organelles Small structures (NOT made of membrane) May be free or bound (attached) Made of two subunits

Central Vacuole Structure Function LARGE sac made of membrane Found in center of plant cells Function Stores chemicals and water

Smooth Endoplasmic Reticulum Function Makes lipids (oils, phospholipids, steroids) Detoxifies poisons Transport of materials Structure Canals and tubes made of membrane

Rough Endoplasmic Reticulum Structure Canals and tubes made of membrane Have ribosomes attached to the outside Function Transport materials in the cell Make proteins

Golgi Apparatus Structure Function Stacks of membrane sacs has a receiving end (from ER) and a shipping end Function Chemically modifies substances Packages material for transport out of the cell or to other locations within the cell

Vesicles Structure Functions Small membrane “bubbles” that bud off the ER or Golgi Functions Transport materials to new locations

Lysosomes Structure Function Sacs of membrane that contain hydrolytic enzymes found mostly in animal cells Function Use enzymes to break down old organelles In white blood cells are used to destroy bacteria

Mitochondria Structure Function Surrounded by a double membrane Folds found on the inside Contains DNA (separate from nuclear DNA) Function Cellular Respiration Converts energy in sugars into the energy of ATP molecule

Chloroplasts Structure Function Surrounded by a double layer of membrane Disks found inside Function Convert solar energy into chemical energy (food) Site of photosynthesis

Perioxisome Structure Function Small membranous sac Some reactions occurring here produce H2O2 (toxic) So, it also contains an enzyme that converts this to water and oxygen gas

Centrioles Structure Function Made of rings of microtubules Found in pairs that lie at right angles Look similar to a pair of barrels Function Found in animal cells Help in cell division

Cell Wall Structure Function Found outside the plasma membrane Plant  made of cellulose Function Give support to certain cells (plant) Does NOT determine what can get into/out of the cell

Cytoskeleton Structure Made of protein fibers Function Microtubules Hollow tube Microfilaments Small rods Intermediate filaments Function Give the cell shape Help to move organelles around the cell

Components of the cytoskeleton Fig. 4-17 Components of the cytoskeleton Nucleus Nucleus Actin subunit Fibrous subunits Tubulin subunit 7 nm 10 nm 25 nm Microfilament Intermediate filament Microtubule

Flagella Structure Function Same as cilia, but are longer and there are just a few of them Prokaryotes also have them Not made of microtubules Move the cell within its environment

Cilia Structure Function Microtubules that extend from the cell (still covered by the plasma membrane) Short and many of them Function In single-celled organisms move the organism from place to place If anchored in place, can set up a current, moving fluid across the surface of a cell