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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