Cell Structures and Functions

Plasma Membrane Structure –Phospholipid Membrane: Amphipathic Forms a Bilayer (hydrophilic heads on interior and exterior faces of cell) Fluid

Plasma Membrane Function Maintain homeostasis (allow certain things to enter/leave cell so internal processes continue) –Phospholipid bilayer acts as selectively permeable membrane –Proteins act as channels –Carbohydrates act as receptors –Cholesterol decreases fluidity (stabilizes)

Rough Endoplasmic Reticulum –Structure Lipid Bilayer Network Studded with Ribosomes In animal cells, associated with the nuclear membrane –Function Allows cell products (protein) to travel throughout the cytoplasm Protein folding occurs here as well

Smooth Endoplasmic Reticulum Structure –Lipid Bilayer Network Function –Lipid Synthesis –Allows cell products (lipid primarily) to travel throughout the cytoplasm

Golgi Apparatus Structure –Layers of Flattened lipid bilayer vesicles Function –Works with Cell Membrane/ER’s to Convert lipid/protein products to usable forms Transport products throughout/out of cell

Golgi Body: Lysosome Structure –Membrane bound vesicle (golgi body) –Contains digestive enzymes Function –Digest ingested foods –Break-up/Recycle used-up organelles

Golgi Body: Microbodies Structure –Small lipid bilayer vesicles –Example is Peroxisome Function –Associated with mitochondria –Break up hydrogen peroxide (harmful byproduct of aerobic respiration)

Cytoskeletal Elements –Structure Protein filaments (3 types) –Function Allows organelles to move throughout the cell Move the cell during cell division (or in case of muscle cell, expands and contracts the cell)

Mitochondria Structure –Double membrane organelle with isolated compartments Function –Compartments isolate reactions involved with aerobic respiration –Function of aerobic respiration is to produce ATP (usable energy molecule)

Nucleus Structure –Nuclear Membrane and Pores Lipid Bilayer w/ associated protein channels –Chromatin DNA + protein (histones) Function –Nuclear membrane and Pores Controls access to DNA –Chromatin Keeps Genetic information tightly packed Genetic information – info for building proteins

Ribosomes Structure –Made of RNA and Protein –Large and Small Subunits Function –Site of protein manufacturing

Cytosol Structure Aqueous solution (mostly water and ions) Function Fluid medium for chemical reactions

Cilia or Flagella Structure –Protein filaments in a 9+2 arrangement embedded in the membrane Function –Motile Elements of the Cell –Allows cell to move or moves substances around the cell

Vacuoles Structure –Membrane bound vesicles – often made from in-pocketing of plasma membrane. –Contain various cell products for storage Function –Store cell products, food, waste, etc. –In plants, the Central Vacuole contains enzymes and water. When filled, it maintains turgor pressure on the cell wall.

Cell Wall –Structure In plants, made of the polysaccharide cellulose as well as the proteins pectin and lignin. Actually 2 layers, depending on the cell function, the thicknesses of each vary. –Contain openings lined with membrane called Plasmodesmata, that allow things to enter the cell. In fungi, made of nitrogen-rich polysaccharide chitin. –Function Provides protection and support in plant and fungi cells

Chloroplast Structure –Membrane organelle that contains smaller vesicles called Grana –Grana’s membrane has high concentration of chlorophyll Function –Use sunlight energy to produce carbohydrates

Centrosomes Structure –Animal cells (small protein filament bundles called centrioles) –Plant cells (associated cytoskeleton elements) Function –Organizes cytoskeleton during cell division to equally separate chromosomes –Where all cytoskeleton growth originates