Cell Structure & Function
http://koning.ecsu.ctstateu.edu/cell/cell.html
Cell Theory
All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from pre-existing cells through cell division.
Definition of Cell
A cell is the smallest unit that is capable of performing life functions.
They were first identified in 1665.
Examples of Cells
Amoeba Proteus
Plant Stem
Red Blood Cell
Nerve Cell
Bacteria
Two Main Types of Cells
ProkaryoticEukaryotic
Prokaryotic
Do not have structures surrounded by membranesFew internal structuresOne-celled organisms an example would be bacteria
http://library.thinkquest.org/C004535/prokaryotic_cells.html
Eukaryotic
Contain organelles surrounded by membranesMost living organisms
Plant
Animal
http://library.thinkquest.org/C004535/eukaryotic_cells.html
Typical Animal Cell
http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif
http://waynesword.palomar.edu/images/plant3.gif
Typical Plant Cell
Cell Parts
Organelles
Surrounding the Cell
Plasma (Cell) Membrane
Outer membrane of cell that controls movement in and out of the cellMaintains the internal environmentVery thin less than 0.1m thickDouble layer
http://library.thinkquest.org/12413/structures.html
Cell Wall
Found in plant cells, fungi & bacteriaLie on the outside of the plasma membraneSupports & protects cellsSemi-rigid helps hold plants upright
Inside the Cell
Nucleus
The control centre of the cell - directs cell activitiesSeparated from cytoplasm by nuclear envelope (membrane)Contains genetic material - DNA
Nuclear Envelope (Membrane)
Surrounds nucleusMade of two layersOpenings called nuclear pores allow material to enter and leave nucleusHaving a nuclear envelope distinguishes an eukaryotic cell
http://library.thinkquest.org/12413/structures.html
Chromosomes
During the process of cell replication, the DNA in the nucleus becomes organized into chromosomesContain instructions for traits & characteristics
http://library.thinkquest.org/12413/structures.html
Nucleolus
Inside nucleusContains RNA to build proteins
http://library.thinkquest.org/12413/structures.html
Cytosol (Cytoplasm)
Gel-like mixtureSurrounded by the plasma membraneContains hereditary material
Endoplasmic Reticulum
Membranous sacs that package materials, such as proteins, for transport within the cellSmooth type: lacks ribosomesRough type (pictured): ribosomes embedded in surface
http://library.thinkquest.org/12413/structures.html
Golgi Complex (Bodies, Apparatus)
Move proteins out of the cellProtein 'packaging plantAre formed from layers of membranes and vesicles that carry materials out of the cell
http://library.thinkquest.org/12413/structures.html
Ribosomes
Each cell contains thousandsMake proteins (protein factories) this is called protein synthesisFound on endoplasmic reticulum & floating throughout the cell
Mitochondria
Produces chemical energy (ATP adenosine triphosphate) through chemical reactions breaking down fats & carbohydratesControls level of water and other materials in cellRecycles and decomposes proteins, fats, and carbohydrates
http://library.thinkquest.org/12413/structures.html
Lysosome
Digestive 'plant' for proteins, fats, and carbohydratesTransports undigested material to plasma membrane for removalSometimes the lysosome releases its enzymes and causes the cell to undergo a controlled death (for a variety of reasons) - this self-destruction is called apoptosis
Vacuoles
Membrane-bound sacs for storage, digestion, and waste removalContains water solutionHelp plants maintain shape
http://library.thinkquest.org/12413/structures.html
Chloroplast
Found only in plant cellsContains green chlorophyllWhere photosynthesis takes place
http://library.thinkquest.org/12413/structures.html
Cytoskeleton
The cytoskeleton is unique to eukaryotic cells. It is a dynamic three-dimensional structure that fills the cytoplasm. This structure acts as both muscle and skeleton, for movement and stability.
Flagella and Cilia
Typically, cells possess one or two long flagella, whereas ciliated cells have many short cilia. The mammalian spermatozoon has a single flagellum to move the sperm through the Fallopian tubes.Huge numbers of cilia cover the surfaces of mammalian respiratory passages (the nose, pharynx, and trachea), where they dislodge and expel particulate matter that collects in the mucus secretions of these tissues.
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