Eukaryotic Cell Structure

• Chromatin: network of strands that coil into chromosomes just before cell division.
• Chromosomes: contains DNA, protein, some RNA.
• Nucleolus: dark region of chromatin where rRNA is produced and joins with proteins to form the subunits of ribosomes.
• Nuclear envelope: membrane of nucleus.
• Nuclear pores: allow passage of ribosomal subunits, mRNA out; proteins in.

• Non-membrane bound particles where protein synthsis occurs.
• Some occur freely (sometimes in groups), others attach to the ER.
• Receive mRNA from nucleus with aa sequences for proteins.

• Membranous channels and saccules attached to nuclear envelope.
• Rough ER - studded with ribosomes. Creates and modifies proteins, forms vesicles to transport large molecules.
• Smooth ER - no ribosomes. More abundant when lipid synthesis is needed.

3-20 slightly curved saccules. Receives protein and lipid filled vesicles from ER. Modifies, sorts, and packages macromolecules into vesicles some of which go to the plasma membrane to be secreted (exocytosis).

• Vesicles produced by the Golgi apparatus w/low pH and containing digestive enzymes.
• Digests macromolecules into smaller bits, bacteria or other foreign bodies, and takes part in cell death (apoptosis).

Vesicles with enzymes, synthesized by free ribosomes, whose action creates H2O2. H2O2 immediately broken down by anoher peroxisomal enzyme called catalase.

• Membranous sacs larger than vesicles. Store substances, regulate water in cell, and digest nutrients.
• Plant cells usually have a large central vacuole. Maintains hydrostatic pressure (turgor), permanently stores all waste, and digests organelles.

Use solar energy to synthesize carbs. Type of plastid (own DNA). Double membrane around space called stroma filled with stacks of thylakoids (called granum). Produced by division of existing plastids.

Process by which energy of carbs is converted to ATP.

Outer membrane and inner membrane forming folds (cristae) projecting inside and increasing surface area; surrounds a matrix which is concentrated mix of enzymes supplying chemical energy to create ATP. Own DNA and ribosomes.

Form a dense, comple web just under plasma membrane (helps structure). Involved with movement of cells and organelles. Interact with motor molecules (proteins such as myosin) which pull along actin filaments in the presence of ATP.

Ropelike assembly of fibrous polypeptides. Keratin is an example. Add structure and can disassemble when phosphate is added by kinase.

• Made of globular protein called tubulin of two types, alpha and beta, which come together as dimers which arrange themselves into rows. Assembly regultaed by centrosomes. Associated with motor molecules kinesin and dynein.
• Before cell division they reassemble into a spindle that distributes chromosomes then reassmble into former array at the end of division.

Major microtubule organizing center for the cell.

Short cylinders located in pairs at each centrosome; of unknown function.

Allows movement.