Chapter 3 Review By: Austin

Basics Concepts  Cells are the building blocks of all plants and animals.  Cells are produced by the division of preexisting cells.  Cells are the smallest units that perform all vital physiological functions.  Each cells maintains homeostasis at the cellular level.  Homeostasis at the tissue, organ system, and individual levels reflects on the combined and coordinated actions of many cells.

Studying Cells O Cytology- is the study of the structure and functions of cells. Transmission Electron Microscopy The electrons pass through an ultrathin section to strike a photographic plate. The result is a transmission electron micrograph (TEM). It shows the fine structure of cell membranes and intracellular structures. Scanning Electron Microscopy The electrons bounce off the exposed surfaces to create a scanning electron micrograph (SEM). Although it provides less magnification, it provides a three- dimensional perspective on the cell structure.

Cell Anatomy O The cell membrane is what separates the extracellular fluid from the cytosol and cellular organelles. O The extracellular fluid is a watery medium that our cells float in. O The cytosol, which is inside the cell, contain dissolved nutrients, ions, soluble and insoluble proteins, and waste products of the cell. O The organelles are structures that perform specific functions inside the cell.

Cell Membrane  The cell membrane forms the outer boundary of the cell. It is made up of phospholipids, proteins, glycolipids, and cholesterol.  Its functions include physical isolation, regulation of exchange with environment, sensitivity, and structural support.

The cell and its environment  The cell membrane controls all communication with its environment because it has to maintain homeostasis within the cell.  The cell membrane controls osmotic concentration.  The cell membrane controls everything in and out of the cell depending on a cell’s permeability.

Cellular Organelles

Cell Energy O Mitochondria have an outer membrane and an inner membrane that contains many folds called cristae. The cristae increase the area exposed to the matrix, which contain metabolic enzymes that perform reactions that provide energy. O Respiratory enzymes produce ATP through the breakdown of organic molecules in a series of reactions that consume oxygen and generate carbon dioxide.

The Nucleus  The nucleus directs the processes that take place in the cytosol.  Chemical communications between the nucleus and cytosol go through the nuclear pores.  The nucleus controls cellular operations through its regulation of protein synthesis.  The nucleolus synthesize the components of ribosomes.  The nucleoplasm contains ions, enzymes, RNA and DNA nucleotides, proteins, and small amounts of DNA and RNA.

Cell Life Cycle The first phase is interphase then comes prophase were the two centrioles move to opposite poles. Then the nucleus dissolves in prophase and the chromosomes are lined up during metaphase. In anaphase the chromosomes are pulled apart to opposite poles. Then in telophase the nucleus reappears around the chromatid and cytokinesis begins and two new daughter cells are formed.

Cell Life Cycle InterphaseG-1 PhaseS PhaseG-2 PhaseProphaseMetaphaseAnaphaseTelophase Mitosis

Cell Division

Cell Life Cycle Terms  Cell Division  Mitosis  Somatic Cells  Reproductive Cells  Interphase  G-o Phase  G-1 Phase  G-2 Phase  S Phase  DNA Replication  DNA Polymerase  Ligases  G-2 Phase  G-m Phase (Mitosis)  Prophase  Chromatids  Centromere  Spindle Fibers  Metaphase  Metaphase Plate  Anaphase  Daughter chromosomes  Telophase  Cytokinesis  Mitotic Rate  Stem Cell

Transmembrane potential o Transmembrane potential depend on two factors one passive and one active: o The passive factor is the membrane permeability for sodium and potassium. o The active factor is the presence of the sodium-potassium exchange pump in the membrane surface. o The cell membrane regulates what enters and leaves the cell.

Cell Attachment O Cell attachment to one another occur at cell junctions; there are four types of cell junctions gap junctions, tight junctions, intermediate junctions, and desmosomes.

Gap Junctions  Gap junctions is when two cells are held together by an interlocking of membrane proteins.  Gap junctions normally occur in cardiac muscle and smooth muscle tissue and occasionally between nerve cells.

Tight Junctions  In a tight junction there is a partial fusion of the lipid portions of the two cell membranes.  Tight junctions are the strongest intracellular connection.  They provide mechanical strength and block the passage of water and solutes between cells.  Mainly there found where extracellular fluid is different. i.e. digestive tract

Intermediate Junctions At an intermediate junction the opposing cell membranes are held together by a thick layer of proteoglycans. This is called intracellular cement; while hyaluronic acid is the most important one. This adds strength and helps stabilize the shape of the cell.

Desmosomes  Desmosomes contain a very thin proteoglycan layer between the opposing cell membranes, reinforced by filaments that lock the two cells together.  These are very strong and can resist stretching and twisting.  Mainly between the cells in the superficial layers of the skin.

StructureCompositionFunction Cell MembraneLipid bilayer, containing phospholipids, steroids, and proteins Isolation, protection, sensitivity, organization CytosolFluid component of cytoplasmDistributes materials by diffusion Cytoskeleton: Microtubules Microfilaments Proteins organized in fine filaments or slender tubes Strength, movement of cellular structures and materials MicrovilliMembrane extensions containing microfilaments Absorption of extracellular materials CiliaMembrane extensions containing microtubules in 9x2 arrangement Movement of materials over surface CentriolesTwo centrioles each composed of microtubules in 9x3 array Movement of chromosomes during cell division RibosomesRNA + proteinProtein Synthesis MitochondriaDouble membrane, with inner fold enclosing metabolic enzymes Produce 95% of ATP required by cell.

StructureCompositionFunction NucleusNucleoplasm containing nucleotides, enzymes, and nucleoproteins surrounded by nuclear envelope Control of metabolism; storage and processing genetic information NucleolusDense region in nucleoplasmSite of RNA synthesis Endoplasmic Reticulum Network of membranous channels extending throughout the cytoplasm Synthesis of secretory products; intracellular storage and transportation Rough ERRibosomes attached to membranesSecretory protein synthesis Smooth ERLacks attached ribosomesLipid and carbohydrate synthesis Golgi ApparatusSeries of stacked, flattened membranes(saccules) containing chambers(cisternae) Storage, alteration, and packaging of secretory products and lysosomes. LysosomesVesicles containing powerful digestive enzymes Intracellular removal of damaged organelles or of pathogens PeroxisomesVesicles containing degradative enzymes Neutralization of toxic compounds