Cell Structure & Function http://koning.ecsu.ctstateu.edu/cell/cell.html

Definition of Cell A cell is the smallest unit that is capable of performing life functions.

Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

Prokaryotic Eukaryotic Two Types of Cells Prokaryotic Eukaryotic

Prokaryotic Do not have membrane bound organelles (structures surrounded by membranes) Few internal structures One-celled organisms Example: Bacteria http://library.thinkquest.org/C004535/prokaryotic_cells.html

Eukaryotic Cells Contain organelles surrounded by membranes Includes most living organisms both single & multi-cellular Carry out more specialized functions than prokaryotic cells b/c of their complex organization Animal Plant http://library.thinkquest.org/C004535/eukaryotic_cells.html

“Typical” Animal Cell http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif

“Typical” Plant Cell http://waynesword.palomar.edu/images/plant3.gif

Organelles “little organs” Cell Parts Organelles “little organs”

Surrounding the Cell

Cell Membrane Also called the Plasma Membrane Outer membrane of cell that controls movement in and out of the cell Double layer called the phospholipid bilayer http://library.thinkquest.org/12413/structures.html

Cell Wall Most commonly found in plant cells, fungi cells & bacteria Supports & protects cells Double layer http://library.thinkquest.org/12413/structures.html

Flagella & Cilia Flagella- whip-like projections Cilia- hair-like projections Both are used for movement; composed of cytoskeleton filaments & protein; covered in an extension of the cell membrane

Inside the Cell

Nucleus Directs cell activities Separated from cytoplasm by nuclear membrane Contains genetic material (DNA) inside the nucleolus

Nuclear Membrane Surrounds nucleus Made of two layers Openings called nuclear pores allow material to enter and leave nucleus http://library.thinkquest.org/12413/structures.html

Chromatin/Chromosomes In nucleus Chromatin is DNA & protein in a loose network of bumpy threads (condenses to form chromosomes during cell division) Contain instructions for traits & characteristics http://library.thinkquest.org/12413/structures.html

Nucleolus Inside nucleus Contains RNA to build proteins ribosome parts are made here http://library.thinkquest.org/12413/structures.html

Cytoplasm Gel-like mixture surrounded by cell membrane Organelles are supported by the cytoplasm Site of most cellular activities (like the factory area of the cell)

Endoplasmic Reticulum System of canals that coils & twists through the cytoplasm Moves materials around in cell Smooth ER: lacks ribosomes, functions in lipid metabolism (making & breaking down cholesterol and fats) and detoxification of drugs and pesticides http://library.thinkquest.org/12413/structures.html

Endoplasmic reticulum (cont.) Rough ER: Has ribosomes on the surface Proteins made by the ribosomes enter the rough ER then fold into their functional 3-dimensional shape. They are then transported to other areas of the cell in vesicles.

Ribosomes Each cell contains thousands Makes proteins Floating free throughout the cell http://library.thinkquest.org/12413/structures.html

Mitochondria Produces energy (ATP) by breaking down food (cellular respiration) Regulates cellular metabolism Surrounded by 2 membranes Has its own DNA & ribosomes! ‘busy’ cells have hundreds of mitochondria http://library.thinkquest.org/12413/structures.htl

Golgi Bodies or Golgi Apparatus Stack of flattened membrane bound sacs Major function is to modify & package proteins Modifies, sorts, and packages materials for export from the cell http://library.thinkquest.org/12413/structures.html

Lysosome Contains powerful digestive enzymes Digestive ‘factory' for proteins, fats, and carbohydrates Abundant in cells that dispose of bacteria & cell debris Cell is digested if a lysosome explodes http://library.thinkquest.org/12413/structures.html

Peroxisomes Most important function is to convert free radicals into hydrogen peroxide (H2O2) If left to accumulate, free radicals can have devastating effects on cells

Vacuoles/ Central Vacuole Membrane-bound sacs for storage, digestion, and waste removal Contains water, ions, nutrients, & wastes Very large in plants; maintain plant shape by holding lots of water http://library.thinkquest.org/12413/structures.html

Chloroplast A plastid found in plant & algae cells Contains green chlorophyll Where photosynthesis takes place Flattened sacs are called thylakoids http://library.thinkquest.org/12413/structures.html

Cytoskeleton Elaborate network of protein structures that extends throughout the cytoplasm Acts as the cells “bones & muscles” by providing an internal framework that determines cell shape, supports other organelles, and provides a route for intracellular transport Made up of microfilaments, microtubules, & intermediate filaments

Centrioles Rod-shaped structures that direct the formation of spindle fibers during mitosis & meiosis Made of microtubles

Vesicles These are not actually organelles. This is a generic term for any material that is enclosed in a membrane. Vesicles are pinched off from the golgi body, cell membrane, and ER. They may contain hormones, proteins, nutrients, etc.