Eukaryotic Cell Organelles

Lesson Objectives Identify the structure and function of the parts of a typical eukaryotic cell. Compare and contrast structures of plant and animal cells.

Main Idea Eukaryotic cells contain organelles that allow the specialization and the separation of functions within the cell.

Boundaries Plasma Membrane –Selectively permeable –Around outside of cell and eukaryotic cell organelles –Composed of phospholipid bilayer –Flexible

Boundaries Cell Wall –Found in prokaryotes, plant cells, fungi, bacteria, and some protists –Very porous; not selective on what comes through –Rigid –Located outside the plasma membrane –Provides support and protection –Made of cellulose, a carbohydrate (sugar) polysaccharide

Boundaries

Cytoskeleton and Cytoplasm Cytoskeleton –Supporting network of long, thin protein fibers –Forms a framework for the cell –Provides an anchor for the organelles –Made of microtubules and microfilaments rapidly assemble and disassemble for movement purposes. Cytoplasm –Internal environment of the cell –Semifluid –Like jell-o –Prokaryotes perform all chemical functions in the cytoplasm.

The Control Center Nucleus –Manager of the eukaryotic cell –Contains the DNA, which has all the directions for making proteins for growth, function, and reproduction Controls the activity of other organelles because of this! –Master set of directions for protein synthesis is contained in chromatin, which are strands of DNA attached to proteins.

The Control Center Nucleolus –Site of ribosome production Nuclear Envelope –Double membrane surrounding the nucleus –Similar to plasma membrane –Nuclear pores allow larger-sized substances to move in and out of the nucleus

The Nucleus

Ribosomes –Site where cells assemble enzymes and other proteins according to the DNA sequence –Made of RNA and proteins –NOT bound by a membrane –Found in both eukaryotic and prokaryotic cells –Found freely floating in the cytoplasm and attached to parts of the endoplasmic reticulum

Assembly and Transport Endoplasmic Reticulum (ER) –Membrane system of folded sacs and interconnected channels –Provides a big workspace within the cell –Looks like an accordion or fan folded into the cell –Rough ER has ribosomes attached and serves as the site for protein and lipid synthesis The site where ribosomes attach to the ER is where protein synthesis takes place. –Proteins made on ER have specific functions and can go anywhere –Smooth ER has no ribosomes is the site of carbohydrate and lipid synthesis –Compared to a road or highway

The Endoplasmic Reticulum

Assembly and Transport Golgi Apparatus –After proteins are produced, they are transferred to here –System of flattened, tubular membranes –Modifies, sorts, and packages proteins for their appropriate destination –Like the post office

Golgi Apparatus

Vacuoles and Storage Vacuoles –Membrane bound spaces –Temporary storage of materials –Stores food, enzymes, other materials needed, and waste products –Plant cells usually have one large vacuole –Animal cells have many small vacuoles

Vacuoles

Lysosomes and Recycling Lysosomes –Contain digestive enzymes –Ex. clean-up crew –Found in animal cells and rarely plant cells –Digests excess or worn out organelles, food, and engulfed viruses or bacteria –Membrane prevents the digestive enzymes from destroying the cell

Lysosomes and Recycling Lysosomes can fuse with a vacuole and dispense their enzymes into it. This procedure digests the contents of the vacuole. Sometimes, lysosomes eat the cell that contains it. Ex. Tadpole’s tail

A Lysosome

Centrioles Organelles made of microtubules that function during cell division Located in the cytoplasm of ANIMAL cells and most protists Found near the nucleus

Mitochondria Membrane bound organelles found in both plant and animal cells that transform energy, usually from sugars, for the cell. –Ex. Generators or powerhouses Has an outer membrane and highly folded inner membrane. Inner folds provide a large surface area where energy-storing molecules are produced by breaking the bonds in sugars. Layers of the inner folds are called cristae. Can vary in number depending on the type of cell in which it resides.

The Powerhouse

Chloroplasts Cell organelles that capture solar light energy and produce food to store for a later time. Found in plant cells and responsible for photosynthesis Has a double membrane, with an outer membrane and a folded inner membrane system of thylakoids, that resembles a stack of coins. Stroma is the fluid that surrounds the inner membranes.

Chloroplasts Contain the green pigment chlorophyll. Chlorophyll is responsible for trapping the light energy and giving leaves and stems their green color.

Support and Locomotion Cilia and flagella help in locomotion and feeding. They are composed of microtubules (thin, hollow protein cylinders) with one central pair surrounded by nine additional pairs. The entire structure is surrounded by a plasma membrane.

Support and Locomotion Cilia - short, numerous, hair like projections that move in a wave like motion –Also found on stationary cells to help move substances across the cell Flagella - longer projections that move with a whip like motion For unicellular organisms, cilia and flagella are the major means of locomotion.

Plant Cell

Animal Cell