IS2 1.5 Structure and Functions of Cell Parts, and Comparing Types of Cells PDF

Recall that cells… Are the basic unit of life Are microscopic Can be prokaryotic or eukaryotic A Panoramic View of Eukaryotic Cells Basic Structure of a Eukaryotic Cell Plasma membrane Regulates the traffic of molecules between the cell and their surroundings Nucleus A memb...

Recall that cells… Are the basic unit of life Are microscopic Can be prokaryotic or eukaryotic A Panoramic View of Eukaryotic Cells Basic Structure of a Eukaryotic Cell Plasma membrane Regulates the traffic of molecules between the cell and their surroundings Nucleus A membrane-enclosed organelle that contains genes The control center of the cell Cytoplasm The entire region between the plasma membrane and the nucleus Made up of cytosol and organelles Plant Cell vs. Animal Cell Major Differences Plant cells have chloroplasts; animal cells don’t have. Plant cells have walls exterior to their plasma membranes; animal cells don’t have cell walls. Concept Check! What are the three major parts of a eukaryotic cell? What is the difference between the cytoplasm and the cytosol? Name two structures in plant cells that animal cells lack. Membrane Structure and Function The plasma membrane is the edge of life. It is the boundary that separates the living cell from its nonliving surroundings.  Fluid Mosaic Model fluid mosaic model of the cell membrane is how scientists describe what the cell membrane looks and functions like The cell membrane is primarily made up of three things: 1. Phospholipids; 2. Cholesterol; 3. Proteins  a type of steroid which is helpful in regulating molecules entering and exiting the cell acts as a barrier to protect the cell against various environmental insults help with transport or communication Phospholipid Bilayer The plasma membrane and other membranes of the cell are composed mostly of lipids (phospholipids) and proteins. Has hydrophobic and hydrophilic ends Phospholipid Bilayer The plasma membrane and other membranes of the cell are composed mostly of lipids (phospholipids) and proteins. Has hydrophobic and hydrophilic ends Selective Permeability A membrane allows some substances to cross more easily than others and blocks the passage of some substances altogether. Traffic of materials is regulated by specialized proteins called transport proteins. Concept Check! Why do phospholipids tend to organize into a bilayer in an aqueous solution? What is meant by the term fluid mosaic model? Nucleus and Ribosomes Genetic Control Center of the Cell The Nucleus The control center of the cell Contains the genes – storage of hereditary information necessary for the manufacture of proteins A gene is a specific stretch of DNA that contains the code for the structure of a specific protein. The Nucleus Bordered by a double membrane called the nuclear envelope. The pores (nuclear pore) in the nuclear envelope allow passage of materials between the nucleus and cytoplasm. Ribosomes: Protein Factories Dot-like structures embedded on the rough endoplasmic reticulum or cytoplasm Produced by the nucleolus (in the nucleus) How DNA controls the cell? More commonly known as the central dogma of molecular biology DNA > RNA > Protein Molecular basis of inheritance Concept Check! Why is nucleus regarded as the control center of the cell? How do ribosomes participate in the controlling the flow of genetic information in the cell? The Endomembrane System Manufacturing and Distributing Cellular Products Endoplasmic Reticulum One of the cell’s main manufacturing facilities Produces an enormous variety of molecules A membranous labyrinth of tubes and sacs running in the cytoplasm Comes in two types: rough and smooth  Rough Endoplasmic Reticulum Roughness attributed to the presence of ribosomes Produces two kinds of proteins: membranous and secretory proteins Products of the RER are transported via transport vesicles Smooth Endoplasmic Reticulum Lack ribosomes on the surface A wide variety of enzymes are produced in this structure Synthesis of lipids, including steroids Detoxification of substances Golgi Apparatus An organelle named after its discoverer, Camilo Golgi Cell’s refinery, warehouse, and shipping center It receives, refines, stores, and distributes chemical products of the cell. Lysosomes Literally means “breakdown body” A membrane- enclosed sac of digestive enzymes These enzymes can break down macromolecules such as proteins, polysaccharides, fats, and nucleic acids  Lysosomal Activity Lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself.  Vacuoles These are membranous sacs that bud from the ER, Golgi, or plasma membrane. Come in different sizes and have a variety of functions In animal cells, vacuoles are generally small and help sequester waste products. In plant cells, vacuoles help maintain water balance. Vacuole Modifications A review of the endomembrane system Concept Check! What makes RER rough? What is the relationship between the Golgi apparatus and the ER in a protein-secreting cell? Chloroplasts and Mitochondria Energy Conversion Endosymbiotic Theory explains the evolutionary origin of chloroplasts and mitochondria. Chloroplasts Organelles of plants and some protists that perform photosynthesis Has three major compartments: the space between two membranes that envelope the chloroplast, the stroma, and the interior of a network of membrane- enclosed tubes and disks. Mitochondrion Powerhouse of the cell Site of cellular respiration Organelle that harvests energy from sugars and other food molecules and converts it to another form of chemical energy called ATP Basic Structure of a Mitochondrion Chloroplasts vs. Mitochondria Concept Check! How are mitochondria and chloroplasts related? What does photosynthesis accomplish? What is cellular respiration? The Cytoskeleton Cell Shape and Movement Cytoskeleton Serves as both skeleton and muscles for the cell, functioning in both support and movement. Maintains the shape of the cell through microtubules These microtubules are made of globular proteins called tubulins Also involved in the locomotion of the cell by dismantling in one part of the cell. Microtubules Centrioles Tubelike structures that aid in cell division Generally found close to the nucleus Specialized microtubules that guide the movement of chromosomes when cells divide Cilia and Flagella Motile appendages – extensions from the cell that aid locomotion. Flagella propel the cell by an undulating wavelike motion. Cilia are generally shorter and more numerous than flagella and promote movement by a coordinated back-and-forth motion. Comparing Type of Cells