Cells and cell cycle

Cytoplasm 

• Cellular material outside the nucleus but inside the plasma membrane.

Cytoskeleton 

• Our skeleton supports many structures of our bodies, the cytoskeleton supports the cell and holds the nucleus and other organelles in place. 
• Some components of the cytoskelton are responsible for changes in cell shape and the movement of cell organelles 
• Cytoskelton consists of three groups of proteins, 1)microtubules, 2)actin filaments, 3)intermediate filaments 

Microtubules

• Hollow tubes composed primarily of protein units called tubulin. 
• Are about 25 nanometers in diameter, with walls about 5 nm thick 
• Vary in length but are normally several micrometers long. 
• Microtubule length can change as tubulin subunits are added or removed, 
• Play a variety of roles in cells. 
• Help provide support and structure to the cytoplasm. 

Cytoplasmic inclusions 

• Contain cytoplasmic inclusions, which are aggregates if chemicals either produced or taken in by cell 
• Dust, minerals and dyes can also accumulate in the cytoplasm 

Cystosol 

• Fluid portion of the cytosol. 
• Colloid, a viscous solution containing dissolved ions and molecules as well as suspebded molecules, called proteins. 
• Many of these proteins are enzymes that catalyze the breakdown of molecules for energy or the synthesis of sugards, fatty acids, amino acids and other molecules. 
• Other proteins in the cystol make up the cytoskeleton anc cytoplasmic inclusions. 

Actin filaments 

• Are called microfilaments, are small fibris, about 8 nm in diameter, that form bundles, sheets or networks in the cytoplas, 
• Intermediate filaments are protein fibres about 10 nm in diameter that provide mechanical strenth to cells. 

Organelles 

• Organelles are structures within cells that are specilaized for particular functions, such as manufacturing proteins or producing ATP. 
• Interior of the membrane-bound organelles is seperated from the cytosplasm, creating subcellular compartments having their own enzymes capable of carrying out unique chemical reactions. 

Nucleus 

• The nucleus is a large, membrane-bound structure usually located near the center of the cell. 
• May be spherical, enlogated or lobed, depending on the cell type. 
• All body cells have a nucleus at some point, some loose their nucleus. 
• Nucleus contains nucleoplasm surrounded by a nuclear envelope. Composed of two membranes separated by a space. 
• Many points on the surface of the nuclear envelope, inner and outer membrane fuse to form porelike structure called nuclear pores. 
• Molecules move between the nucleus and cytoplasm through the openings. 
• DNA is found within the nucleus, small amounys of DNA is also found ewithin the motochondria. 
• DNA and associated proteins are organized into discrete structures called chromosomes. 
• Associated proteins incluse histnes
• Chromosomes are dispered throughout the nucleus as delicate filaments collectively reffered to as chromatin. 

Endoplasmic reticulum 

• Outer membrane of the nuclear envelop is continuous with a series of membranes distributed throughout the cytoplasm of the cell. 
• Contains interconnecting sacs and tubules. 
• Inferior spaces of those sacs and tubules are called cisternae. 
• Rough endoplasmic reticulum is called rough because ribosomes are attached to it. Proteins are produced. 
• Smooth endoplasmic reticulum, manufactures lipids and carbonhydrates. Participates in detoxification. 

Golgi apparatus 

• Composed of flattened, membrous sacs, containing cisternae stacked on each other. 
• Modifies, packages and sitributes…