Cell Structure and Function PDF

Cell Structure and Function  Plasma Membrane Contains cell contents Double layer of phospholipids & proteins  Phospholipids Polar – Hydrophylic head – Hydrophobic tail Interacts with water Movement Across the Plasma Membrane A few molecules move freely – Wate...

Cell Structure and Function  Plasma Membrane Contains cell contents Double layer of phospholipids & proteins  Phospholipids Polar – Hydrophylic head – Hydrophobic tail Interacts with water Movement Across the Plasma Membrane A few molecules move freely – Water, Carbon dioxide, Ammonia, Oxygen Carrier proteins transport some molecules – Proteins embedded in lipid bilayer – Fluid mosaic model – describes fluid nature of a lipid bilayer with proteins  Membrane Proteins 1. Channels or transporters – Move molecules in one direction 2. Receptors – Recognize certain chemicals  Membrane Proteins 3. Glycoproteins – Identify cell type 4. Enzymes – Catalyze production of substances  Cytoplasm Viscous fluid containing organelles components of cytoplasm – Interconnected filaments & fibers – Fluid = cytosol – Organelles (not nucleus) – storage substances  Cytoskeleton Filaments & fibers Made of 3 fiber types – Microfilaments – Microtubules – Intermediate filaments 3 functions: – mechanical support – anchor organelles – help move substances A = actin, IF = intermediate filament, MT = microtubule  Cilia & Flagella Provide motility Cilia – Short – Used to move substances outside human cells Flagella – Whip-like extensions – Found on sperm cells Basal bodies like centrioles Cilia & Flagella Structure Bundles of microtubules With plasma membrane  Centrioles Pairs of microtubular structures Play a role in cell division  Membranous Organelles Functional components within cytoplasm Bound by membranes  Nucleus Control center of cell Double membrane Contains – Chromosomes – Nucleolus  Nuclear Envelope Separates nucleus from rest of cell Double membrane Has pores  DNA Hereditary material Chromosomes – DNA – Protiens – Form for cell division Chromatin  Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes  Endoplasmic Reticulum Helps move substances within cells Network of interconnected membranes Two types – Rough endoplasmic reticulum – Smooth endoplasmic reticulum Rough Endoplasmic Reticulum Ribosomes attached to surface – Manufacture protiens – Not all ribosomes attached to rough ER May modify proteins from ribosomes Smooth Endoplasmic Reticulum No attached ribosomes Has enzymes that help build molecules – Carbohydrates – Lipids