UNIT: #3 Cell Structure and Function
Organelle Structures of the Cell Organelle: Specialized structure of the cell that carries out a specific function, “organ like”. The cell is often compared to a factory. These organelle structures work to produce a product.
Cell Membrane (Both) • Composed of several molecules, the most important is Lipids, which form a bilayer. • The cell membrane separates the cell from its surroundings. • It regulates what enters & leaves the cell. • Functions: protection and support.
Cell Wall (Plant) • Found in Plant, Algae, & some Bacteria. • Is found outside the cell membrane, it actually surrounds the cell membrane. • It is very porous, allows for water, oxygen, carbon dioxide and others to pass through it. • The cell wall is both elastic & rigid. • Functions: Protection, Support, Regulation.
Nucleus (Both) • Large dark round structure usually in the center of the cell. • Is known as the information center of the cell. • Sometimes called the brain of the cell. • Function: To direct all activities of the cell and store DNA.
Nucleolus (Both) • Made up of RNA and other proteins. • Function: To make ribosomes. Nuclear Envelope (Both) • Two layer membrane that surrounds the nucleus, Function: Acts as border between the nucleus and the rest of the cell. Chromosomes (Both) • The DNA of the cell is stored on the chromosome inside the nucleus. Shaped like an X. • The chromosome passes genetic information from generation to generation.
Cytoplasm (Both) • The space or area between the nucleus and the cell membrane. • Gel or jelly like. • Function: Hold and/or support the organelles.
Ribosomes (Both) • Small particles of RNA and protein found throughout the cytoplasm. • Function: To make proteins.
Endoplasmic Reticulum (Both) • Is an internal membrane system. • Function: It is the site where the lipid components of the cell membrane are assembled, along with proteins and other materials. • The part involved in making protein is called the Rough Endoplasmic Reticulum, it has ribosomes on its surface. • The Smooth Endoplasmic Reticulum (doesn’t have ribosomes) stores enzymes used to make lipid membranes.
Golgi Apparatus (Both) • Stack of closely apposed membranes. • Function: It modifies, sorts, and packages molecules for cell storage or secretion.
Lysosomes (Both) • Small organelles filled with enzymes that act as a clean-up crew. • Function: They digest or breakdown; lipids, carbohydrates, and proteins into smaller molecules so that they can be used by the cell. • They also break down organelles that have outlived their usefulness (remove junk that accumulates in the cell). • Many serious diseases can be traced to lysosomes that fail to function properly.
Vacuoles (Both) • Saclike structure. • Function: stores (warehouse) materials like; water, salt, proteins, and carbohydrates. • Can be found in many different types of cells (large central vacuole in plants, several smaller vacuoles in animals). • Play a major role in Homeostasis.
Chloroplasts (Plant) • It stores food and pigments. • Function: stores chlorophyll(pigment), which captures energy from sunlight and converts it into energy for the cell. • May also be called a Plastid.
Mitochondria (Both) • Function: Converts chemical energy stored in food into energy that is more convenient for the cell to use. Known as the powerhouse. • Made of two membranes. • The inner membrane has many folds to increase surface area to improve their function.
Microfilaments (Both) • Thread like structure made of protein • Function: Helps in cell movement & support. Microtubules (Both) • Hallow structure made up of a protein. • Function: Plays a major role in maintaining cell shape and has a role in cell reproduction.
Centrioles(Animal) • Microtubule bundles • Function: Plays a role in cellular reproduction
Cytoskeleton (Both) • A network of protein filaments that • Function: Helps the cell to maintain its shape. • It also is involved in movement.
Cellular Organization Cell (Animal)--> Tissue (Cardiac)--> Organs (Heart)-->Organ System(Cardiovascular)--> Organisms (Humans)