Organelles: Structure & Function

Organelles: Structure & Function

Cell/Plasma Membrane Function: Controls what enters & exits the cell. Structure: Phospholipid bilayer

Nucleus Function: Controls everything in the cell Structure: Contains DNA/chromosomes Enclosed by a porous double membrane called the nuclear membrane.

Nucleolus Function: Takes RNA and makes ribosomes Structure: Dense region inside the nucleus

Ribosomes Function: Links together amino acids to make proteins (that means enzymes too!) Structure: Tiny organelles made of proteins & RNA. Found on Rough ER UC Santa Cruz scientists have for the first time taken a detailed picture, using x-ray crystallography, of a complete ribosome, the small cellular component which translates genetic information into proteins. The bacterial ribosome is composed of three different RNA molecules and more than 50 different proteins arranged in two major subunits, which join together to form the complete ribosome. During protein synthesis, the ribosome binds transfer RNA molecules in three different sites. In this image of the ribosome with transfer RNAs in all three binding sites, the large subunit is gray, the small subunit is violet, and the three transfer RNAs are green, blue, and red. www.aip.org/png/html/ribosome.html

Rough Endoplasmic Reticulum (ER) Function: Transport, "intracellular highway“. Site of protein synthesis; makes more ER Structure: Thin folded membranes that are connected together. HAS ribosomes

Vesicle Membrane-bound containers that carry substances throughout the cell

Golgi Apparatus/Body/Complex Function: Checks, modifies & packages proteins Structure: Closely layered stacks of membrane enclosed discs the Golgi receives newly made proteins and lipids from the ER, puts the finishing touches on them, addresses them, and sends them to their final destinations. One of the places these molecules can end up is in lysosomes.

the Golgi receives newly made proteins and lipids from the ER, puts the finishing touches on them, addresses them, and sends them to their final destinations. One of the places these molecules can end up is in lysosomes.

Lysosome Function: Breaks down food, waste & damaged cell parts all within the cell Structure: Contains enzymes; membrane bound

Peroxisome Function: Protects cell from toxins, especially H2O2. Structure: Contains enzymes; membrane bound www.biologyclass.net/celltheory.html

Vacuole Function: stores materials for cell Structure: fluid filled sacs; small in animal cells; large in plant cells

Plastids Function: Storage sacs in plant cells only! Structure: 3 different types

Plastids Leucoplast – stores starch in roots & stems Chromoplast – stores the orange/yellow pigment 3.Chloroplast- stores the green pigment/ site of photosynthesis

Chloroplast Function: Uses sunlight to create food, photosynthesis (only found in green plants & algae) Structure: 3 membranes; bean shaped; contains chlorophyll (green pigment)

Mitochondria Function: Supplies energy to the cell; site of cellular respiration; ‘powerhouse’ of cell Structure: Bean shaped; 2 membranes; has own DNA & ribosomes

Chloroplast & Mitochondria Both have: more than 1 membrane ‘Powerhouse’ of their cells Contain their own DNA Reproduce independently of the cell Were they once free-living prokaryotic cells?!

Cytoplasm/Cytosol Function: Hold organelles in place & site for chemical reactions Structure: Jelly – like substance between the area of the nucleus & cell membrane

Cytoskeleton Function: Supports & shapes the cell Structure: A network of protein filaments (microtubules, microfilaments) The three fibers of the cytoskeleton–microtubules in blue, intermediate filaments in red, and actin in green–play countless roles in the cell. http://publications.nigms.nih.gov/insidethecell/chapter1.html

Smooth Endoplasmic Reticulum (ER) Function: Transport, "intracellular highway“. Also makes lipids; breaks down toxins such as drugs/alcohol Structure: Thin folded membranes that are connected together. No ribosomes a series of large, flattened membranes that fold back and forth on each other and have a very large surface area. This collection of membranes is called the ENDOPLASMIC RETICULUM, or ER. The ER stretches from the nuclear membrane to the plasma membrane. It serves as a pathway through the cytoplasm, as a support structure for the attachment of other organelles, and as a workstation for the ribosomes. The ER can be divided into two parts: the rough ER and the smooth ER. The rough ER has ribosomes attached to it and provides a surface along which the process of protein assembly can occur. The smooth ER does not have ribosomes and is much more tubular in appearance. In some human cells, the smooth ER produces steroids; in others it regulates calcium levels. In a process that scientists still don't understand, the rough ER manufactures the membranes of the smooth ER. www.beyondbooks.com/lif71/4d.asp

Centrosome/Centrioles Function: Helps the cell divide Structure: Small region of cytoplasm, made up of microtubules; pair of centrioles

Flagellum (flagella = plural) Tail used for movement

Cilium (cilia = plural) Tiny hair-like projections on cell exterior used For movement and gathering food