Cell Organelles and Features

Plasma/Cell Membrane Found in both prokaryotes and eukaryotes Structure: Composed of: phospholipids, cholesterol, and proteins Organization: Phospholipids form a bilayer Proteins and cholesterol are embedded in the bilayer

Cell-Membrane = Fluid Mosaic Model Membrane’s lipids and proteins move laterally within the bilayer The “pattern” of the mosaic is always changing

Function of the Membrane Components 1.Phospholipids a.Control what enter and exit the cell b.Give structure to the cell 2.Proteins a.Control what enter and exit the cell b.Interact with external environment c.Facilitate chemical reactions d.Receive signals 3.Cholesterol a.Maintain fluidity of cell

Nucleus Structure: 1.Nucleoplasm 2.Nuclear envelope with nuclear pores Double membrane 3.Nucleolus Contains DNA

Functions of Nucleus 1.Nucleoplasm Surrounds and protects DNA 2.Nuclear envelope and nuclear pores Controls what enters and exits the nucleus 3.Nucleolus Production of ribosomes (structures that synthesize proteins)

Ribosomes NOT technically organelles Made of proteins and RNA, but have NO membrane Some ribosomes are free-floating in cytoplasm others are bound to the endoplasmic reticulum

Endoplasmic Reticulum (ER) Structure: system of membranous tubes and sacs (cristernae) Two types of ER: Rough and Smooth Rough ER is covered with ribosomes Smooth ER lacks ribosomes

Function of the ER Both types of ER serve as intracellular highway along which molecules move from one part of the cell to the other RER Produces phospholipids and proteins SER Build lipids, such as cholesterol and steroid hormones Detoxifies blood and poisons

Golgi Apparatus Structure: system of flattened, membranous sacs Function: 1.Modifies proteins that it receives from the RER 2.Exports protein to the appropriate location

Vesicles Structure: small, spherically shaped sacs Surrounded by single membrane Vesicles are classified by their contents Often migrate and merge with plasma membrane to release contents Types of Vesicles: lysosomes, peroxisomes, glyoxysomes, endosomes

Lysosomes Contain digestive enzymes Created by the Golgi apparatus Responsible for breaking down cells when it is time for the cell to die = autolysis Food Vacuoles are referred to as endosomes

Peroxisomes Contain enzymes that breakdown alcohol and drugs into peroxide (H 2 O 2 ) Neutralize free radicals Not created by the Golgi apparatus Special type of peroxisome = glycoxysomes Found in seeds of some plants

Ribosomes, ER, Golgi, and Vesicles all play a role in protein synthesis 1.Proteins are assembled by ribosomes on the RER 2.Vesicles transport proteins to the Golgi apparatus 3.Golgi modify proteins and package them into new vesicles 4.Vesicles fuse with the plasma membrane to release proteins outside the cell 5.Vesicles containing enzymes that remain inside the cell form lysosomes, peroxisomes, endosomes, etc.

Mitochondria Structure: Outer and inner membrane Inner membrane has many folds = cristae Contain DNA Function: transfer energy from organic molecules to ATP (cellular respiration)

Cytoskeleton Structure: Network of thin tubes and filaments that crisscross in the cytosol Three major components: 1.Microtubules 2.Microfilaments 3.Intermediate filaments Function: 1.Give shape and support to the cell 2.Acts as a system of internal tracks for intracellular movement

Cytoskeleton

Cilia and Flagella Structure: Hairlike structures that extend from the surface of the cell Part of the cytoskeleton Function: Assist in movement

Centrioles Structure: two short cylinders of microtubules at right angles In the cytoplasm near the nuclear envelope Part of the cytoskeleton of animal cells Function: organize microtubules during cell division

Do all cells contain all of these organelles in the same concentration?

What organelle(s) would you find a lot of in muscle cells?

What organelle(s) would you find a lot of white blood cells?

What organelle(s) would you find in a skin cell?