 Nucleus: contains most of the genes that control entire cell 1. Nuclear envelope: double membrane, encloses nucleus, regulates molecular traffic by pores. 2. Chromosomes: composed of chromatin (DNA & histone protein) 3. Nucleolus: active in the synthesis of ribosomal parts.

 Cytoplasm: area between nucleus & cell membrane. ◦ Cytosol: semifluid portion of the cell membrane ◦ Cellular organelles: bodies with specialized functions suspended in cytosol

 Ribosomes: non-membrane bound organelles made of rRNA and protein, site of protein synthesis. ◦ Free ribosomes: suspended in cytosol; make proteins that function in cytosol ◦ Bound ribosomes: make proteins for membrane inclusion or export.

 Endomembrane System: is a collection of membranes inside & around the cell, related either through direct physical contact or by transfer of membranous vesicles. Many organelles are related through this system.

 Vesicles: membrane enclosed sacs that are pinched off portions of membranes moving from the site of one membrane to another.

 Endoplasmic Reticulum: extensive membranous network continuous with the outer nuclear membrane, composed of rough (ribosome-studded) and smooth (ribosome free) regions

 Smooth ER: lacks attached ribosomes, functions are ◦ Synthesizes lipids, phospholipids, and steroids ◦ Detoxifies drugs & poisons, participates in carbohydrate metabolism; liver cells ◦ Stores calcium ions necessary for muscle contraction

 Rough ER: ribosomes attached to the surface ◦ Folds polypeptide chain into proper conformation, adds oligosaccharide if needed, protein departs in vesicle ◦ Attaches phospholipids to protein produced by attached ribosomes, ER membrane transported to other parts of the cell in vesicles

 Golgi Apparatus: organelle made of stacked, flattened membranous sacs that store, modify, and route the products of the endoplasmic reticulum. ◦ Cis face: receive products contained in transport vesicles from ER, fuse together, and empty contents into Golgi apparatus ◦ Trans face: pinches off vesicles from the Golgi apparatus and transports to other sites

 Lysosome: membrane-enclosed bag of hydrolytic enzymes that digest all major classes of macromolecules. ◦ Functions: intercellular digestion where lysosomes fuse with food vacuoles, recycles cell’s own wastes, and programmed destruction.

 Vacuoles: membrane enclosed sacs larger than vesicles; food vacuoles, contractile vacuoles, and central vacuoles which store inorganic ions, dangerous wastes, or water.

 Peroxisomes: membrane organelles that contain specialized enzymes (peroxide- producing oxidases) for specific metabolic pathways; used to breakdown fatty acids into acetyl-CoA, detoxify alcohol and hydrogen peroxide

 Mitochondria: site of cellular respiration (produces ATP). Smooth outer membrane, inner membrane with folds (cristae) to increase surface area; own DNA due to constant need for enzymes

 Cytoskeleton: a network of microtubules, microfilaments, and intermediate fibers that branch throughout the cytoplasm serving a variety of mechanical and support functions

 Microtubules: hollow cylinder tubes; function as ◦ Cellular support; reinforce cell shape ◦ Tracks for organelle movement; move vesicles from ER to Golgi apparatus ◦ Separate & guide chromosomes during cell division ◦ Make up centrioles in animal cells. Cilia and flagella are examples of microtubules

 Microfilaments: (Actin filaments) solid cylinder rods ◦ Participate in muscle contraction ◦ Provide cellular support; ex. Microfilaments in the core of intestinal microvilli ◦ Responsible for the local contraction of cell; ex. Pseudopods in amoeba, cytoplasmic streaming in plant cells, and cleavage furrows in animal cells

 Tight junctions: hold cells tightly together, no space, common in epithelial cells; water proof tissue.  Desmosomes: rivet cells together at certain points but still allow movement between cells  Gap Junctions: cell membranes connected at certain points to allow direct transport of materials