kilasan memoir

Introduction Structures/Functions Prokaryotes vs. Eukaryotes Types Reproduction Theory Glossary Credits

Within cells there is an intricate network of organelles that all have unique functions. These organelles allow the cell to function properly. Arranged below according to location (nucleus, cytoplasm, and surface) is a description of common organelles. You may click on the organelle's name in the list below to directly reach the feature on that structure.
Cell wallCentriolesChloroplastsChromosomesCytoskeletonEndoplasmic reticulumNuclear membrane
NucleolusGolgi apparatusLysosomeMitochondriaPlasma membraneRibosomesVacuoles

One or more per cell
Spherical shape
Denser than surrounding cytoplasm
Chromosomes- Usually in the form of chromatin- Contains genetic information- Composed of DNA- Thicken for cellular division- Set number per species (i.e. 23 pairs for human)
Nuclear membrane- Surrounds nucleus- Composed of two layers- Numerous openings for nuclear traffic
Nucleolus- Spherical shape- Visible when cell is not dividing- Contains RNA for protein manufacture

Collective term for cytosol and organelles contained within
Colloidal suspension
Cytosol mainly composed of water with free-floating molecules
Viscosity constantly changes
Centrioles- Paired cylindrical organelles near nucleus- Composed of nine tubes, each with three tubules- Involved in cellular division- Lie at right angles to each other
Chloroplasts- A plastid usually found in plant cells- Contain green chlorophyll where photosynthesis takes place
Cytoskeleton- Composed of microtubules- Supports cell and provides shape- Aids movement of materials in and out of cells
Endoplasmic reticulum- Tubular network fused to nuclear membrane- Goes through cytoplasm onto cell membrane- Stores, separates, and serves as cell's transport system- Smooth type: lacks ribosomes- Rough type (pictured): ribosomes embedded in surface
Golgi apparatus- Protein 'packaging plant'- A membrane structure found near nucleus- Composed of numerous layers forming a sac
Lysosome- Digestive 'plant' for proteins, lipids, and carbohydrates- Transports undigested material to cell membrane for removal- Vary in shape depending on process being carried out- Cell breaks down if lysosome explodes
Mitochondria- Second largest organelle with unique genetic structure- Double-layered outer membrane with inner folds called cristae- Energy-producing chemical reactions take place on cristae- Controls level of water and other materials in cell- Recycles and decomposes proteins, fats, and carbohydrates, and forms urea
Ribosomes- Each cell contains thousands- Miniature 'protein factories'- Composes 25% of cell's mass- Stationary type: embedded in rough endoplasmic reticulum- Mobile type: injects proteins directly into cytoplasm
Vacuoles- Membrane-bound sacs for storage, digestion, and waste removal- Contains water solution- Contractile vacuoles for water removal (in unicellular organisms)

Cell wall- Most commonly found in plant cells- Controls turgity- Extracellular structure surrounding plasma membrane- Primary cell wall: extremely elastic- Secondary cell wall: forms around primary cell wall after growth is complete
Plasma membrane- Outer membrane of cell that controls cellular traffic- Contains proteins (left, gray) that span through the membrane and allow passage of materials- Proteins are surrounded by a phospholipid bi-layer.
Organelle Links
Cells and Organelleshttp://www.life.uiuc.edu/bio100/lessons/cells_and_organelles.html
The Insides of Cellshttp://kauai.cudenver.edu:3010/0/nutrition.dir/organelle.html
Structures and Function of Organelleshttp://esg-www.mit.edu:8001/esgbio/cb/organelles.html
Why Are There Organelles?http://iip.ucsd.edu/Step/projects95/cellular.Organelles/WHY.HTM
Cellular Organelleshttp://iip.ucsd.edu/Step/projects95/cellular.Organelles/CELLS.HTM
Microfilaments and Microtubules--The Cytoskeletonhttp://www-class.unl.edu/bios201/group6/cytoskel.html
Eukaryotic Cell Membrane or Plasma Membranehttp://www.bio.mtu.edu/campbell/eukaryot.htm
The Nucleus, Nucleolus, Nuclear Envelope, and everything you ever wanted to know about DNA (but were afraid to ask)http://www-class.unl.edu/bios201/group6/nucleus.html
Lysosomeshttp://www-class.unl.edu/bios201/group6/lyso.html
The Rough and Smooth Endoplasmic Reticulumhttp://www-class.unl.edu/bios201/group6/er.html
The Endoplasmic Reticulumhttp://lenti.med.umn.edu/~mwd/back/cell_www/chapter2/ER.html
The Golgi Bodieshttp://www-class.unl.edu/bios201/group6/golgi.html
Centrioleshttp://www-class.unl.edu/bios201/group6/centrio.html
Mitochondriahttp://www-class.unl.edu/bios201/group6/mitochon.html