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.

They were first identified in 1665. 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 Bacteria Red Blood Cell Nerve Cell

Prokaryotic Eukaryotic Two Main Types of Cells Prokaryotic Eukaryotic

Prokaryotic Do not have structures surrounded by membranes Few internal structures One-celled organisms – an example would be bacteria http://library.thinkquest.org/C004535/prokaryotic_cells.html

Eukaryotic Contain organelles surrounded by membranes Most 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

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

Cell Parts Organelles

Surrounding the Cell

Plasma (Cell) Membrane Outer membrane of cell that controls movement in and out of the cell Maintains the internal environment Very thin – less than 0.1µm thick Double layer http://library.thinkquest.org/12413/structures.html

Cell Wall Found in plant cells, fungi & bacteria Lie on the outside of the plasma membrane Supports & protects cells Semi-rigid – helps hold plants upright

Inside the Cell

Nucleus The control centre of the cell - directs cell activities Separated from cytoplasm by nuclear envelope (membrane) Contains genetic material - DNA

Nuclear Envelope (Membrane) Surrounds nucleus Made of two layers Openings called nuclear pores allow material to enter and leave nucleus Having 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 chromosomes Contain instructions for traits & characteristics http://library.thinkquest.org/12413/structures.html

Nucleolus Inside nucleus Contains RNA to build proteins http://library.thinkquest.org/12413/structures.html

Cytosol (Cytoplasm) Gel-like mixture Surrounded by the plasma membrane Contains hereditary material

Endoplasmic Reticulum Membranous sacs that package materials, such as proteins, for transport within the cell Smooth type: lacks ribosomes Rough type (pictured): ribosomes embedded in surface http://library.thinkquest.org/12413/structures.html

Golgi Complex (Bodies, Apparatus) Move proteins out of the cell Protein 'packaging plant‘ Are 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 thousands Make proteins (‘protein factories’) – this is called protein synthesis Found on endoplasmic reticulum & floating throughout the cell

Mitochondria Produces chemical energy (ATP – adenosine triphosphate) through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates http://library.thinkquest.org/12413/structures.html

Lysosome Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to plasma membrane for removal Sometimes 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 removal Contains water solution Help plants maintain shape http://library.thinkquest.org/12413/structures.html

Chloroplast Found only in plant cells Contains green chlorophyll Where 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.