Cell structure & Function

Cell Wall Main function – provide support & protection for the cell Made of cellulose (carbohydrates) and protiens Located outside the cell membrane of plant, fungi, and some protist cells

Cell Membrane Main function – outer boundary of cell; regulates what can enter and exit the cell Composed of a phospholipid bilayer w/ proteins embedded in the membranes; carbohydrates may attach to proteins

Cytoplasm Main function – substance where organelles are suspended; site of many chemical reactions Fluid substance that fills the space between the cell membrane and the nucleus

Nucleus Main function – controls most cell processes and contains hereditary information (DNA) Composed of a Nuclear membrane Nuclear pores Nucleolus Chromatin/Chromosomes Located in all eukaryotic cells Scanning ↑ Transmission ↓

Chromatin/Chromosomes Chromatin – DNA & Protein when it is loose and thread-like; granular looking; most of the time Chromosomes – DNA & Protein when it condenses to form distinct structures; when cells are dividing

nucleolus Main function – production / assembly of ribosomes Dense region within the nucleus

Nuclear Membrane Main function – surround and protect the contents of the nucleus Double membrane layer Dotted with thousands of nuclear pore which allow material to move into and out of the nucleus

Cytoskeleton Main function – help the cell maintain its shape; also involved in many forms of cell movement Network of protein filaments Microfilaments – smallest; movement & support Intermediate filaments – medium sized Microtubules – largest; transport; cilia; flagella

Ribosomes Main function – site of protein synthesis Composed of RNA and protein Can be free floating in the cytoplasm or attached to endoplasmic reticulum

Endoplasmic Reticulum Rough ER Main function – manufacture and distribution of proteins; ribosomes are attached Smooth ER Main function – manufacture of lipids and break down toxins; NO ribosomes are attached

Golgi Apparatus Main Function – modifies, packages, and distributes material in the cell; Material is received from the ER, modified in the Golgi, then sent to the cell or out of cell. Stack of membranes

Lysosome Main function – break down food and/or worn out organelles Small sack containing digestive enzymes

Vacuole Main function – store materials such as water, salts, proteins, and carbohydrates Plants have a large central vacuole that help the plant stand upright Saclike structures

Chloroplasts Main function – use energy from sunlight to make energy-rich food molecules; site of photosynthesis Double membrane structure that contain large states of green membranes; green color is due to the pigment chlorophyll

Mitochondria Main function – use energy from food to make high-energy compounds that eh cell can use to power growth, development, and movement Double membrane structure; inner membrane is highly folded

Theory that states - mitochondria and chloroplasts are descendents from ancient prokaryotic cells that were engulfed by other cells; the two cells formed a symbiotic relationship where both cells benefited. Evidence = mitochondria & chloroplasts have DNA, ribosomes, and can divide independently of the cell Endosymbiosis