Chapter 7 Cell Structure & Function Class Notes 2015 -

Chapter 7Cell Structure & Function1

The Cell Theory1. All living things are made up of cells.2. Cells are the basic unit of structure &function in living things3. Cells reproduce

Scientists1. Robert Hooke (1665): Discoveredthat cork was made up of tinychambers .he call them cells.2. Anton van Leeuwenhoek (1674):Observed tiny organisms in drops ofpond water using a simplemicroscope.

Scientists (continued)3. Matthias Schleiden (1838): All plantsare made up of cells.!4. Theodor Schwann (1839): All animalsare made up of cells.!5. Rudolph Virchow (1855): Proposed allcells come from pre-existing cells.

Basic Cell Structures1. All cells have:! Cell membraneCytoplasm!!2. Most cells have:Nucleus!

Categories of cellsA. Prokaryotes: Have cell membrane &cytoplasm but no nucleus----smaller and simpler thaneukaryote!Example: Bacteria (E. coli)

Categories of CellsB. Eukaryotes: Have a nucleus, cellmembrane, cytoplasm, and most haveorganellesExamples: Plants, animals, fungi,many microorganisms

Cell Structurea) Cell wall: Plant and bacterial cells notanimal cells. It provides support &protection.!b) Cell membrane: A thin flexible barrieraround the cell. It regulates what enters &leaves a cell.

Cell Structurec) Nucleus: Containsheredity information(DNA) Chromatin:Uncoiled DNA!! Chromosomes:Coiled DNA

Cell Structure Nucleolus: Site ofRNA synthesis,produces ribosomes!! Nuclear Envelope:Surrounds thenucleus, controlswhat enters andleaves the nucleus.

Cell Structured. Cytoskeleton: Network of protein, helps cellkeep its shape; involved with cell motility!Microtubules: Hollow tubes of protein!Microfilaments: Long thin fibers of proteine. Cytoplasm: Material between the nucleus andthe cell membrane; contains the cellorganelles

Cell Organelles: Specializedstructures that perform vital cellular functionsRibosomes:Make proteins based on instructions thatcome from the nucleus (factory machines)Endoplasmicreticulum(ER)Rough ER: ribosomes attached to surface;pathways for transport of materials withinthe cellSmooth ER: No ribosomes attached;pathway for transport of materials withinthe cell

Cell OrganellesGolgi apparatusProcesses, packages & sends proteins &lipids to their final destination w/in cell (PostOffice)!LysosomeContain enzymes that break down largemolecules into smaller parts that can be usedby cell; break down used cell parts. (Garbagemen)VacuoleStore materials like water, starch, etc.;several small in animal cell; one large one inplant cell (Garage)

Concept MapCellsPlant CellsAnimal CellsChloroplast Cell Wall Nucleus Mitochondria RibosomesPhotosynthesisSupport in

Cell OrganellesChloroplastPlant cells; use energy from the sun to makefood; site of photosynthesis. (Solar powerplant)MitochondriaUsually many in cell; release energy fromfood molecules; site of cellular respiration.“Powerhouse of the cell” (Power plant)Cilia & FlagellaLocomotive structures made up ofmicrotubules

StructureProkaryoticEukaryoticAnimal CellEukaryoticPlant CellCell MembraneYesYesYesCell esYesGolgi keletonNoYesyes

Cell Membrane!Selectively permeable: some substancescan pass through it and some cannotLipid Bilayer: 2 layers of lipids the give themembrane a tough, flexible structure; forms abarrier between cell & its surroundings

Cell MembraneProtein Channels & Pumps: embedded inthe lipid bilayer; help move materials acrossthe membrane during facilitated diffusion andactive transportReceptor proteins : embedded in lipidbilayer; receive chemical messages fromother cells (ex: hormones). Homeostasiscan be affected if blocked.

Receptor Proteins

Movement Through the MembraneDiffusion (passive transport): Molecules move fromareas of high concentration to low concentration untilequilibrium is reached.* No energy is required* Equilibrium- the net movement of particlesinto the cell equals the net movement ofparticles out of the cell* Once equilibrium is reached, movement ofmolecules still occurs but in equal amounts

OsmosisDiffusion of water through a selectivelypermeable membrane from areas ofhigh concentration to low concentrationuntil equilibrium is reached* No energy is required22

Osmosis & SolutionsIsotonic Solution: Concentration of solute is equal onboth sides of the membrane; at equilibriumHypotonic Solution: Concentration of solute is lessoutside the membrane than within the cell (belowstrength) causing water to move into the cell;animal cells placed in a hypotonic solution: swell& burstplant cells placed in a hypotonic solution: vacuolesswell, pushing cell content outagainst cell wall.

Isotonic & Hypotonic Solutions

Osmosis & SolutionsHypertonic Solution: Concentration of solute isgreater outside the cell membrane than inside thecell (above strength) causing water to leave thecellanimal cells: shrink due to water lossplant cells: vacuoles collapse due to water loss

Hypertonic Solutions

Osmotic Pressurepressure exerted by osmosis on thehypertonic side of the membranecan cause serious problems for the cellcell is almost always hypertonic tofreshwater -this means that the netmovement of water will go into the cellcells burst if too much water enters27

Movement Through the MembraneFacilitated Diffusion: Protein channels inmembrane help molecules move across themembrane that cannot pass directly (ex: sugar)*From high to low* No energy is required

Active Transport: Movement from lowconcentration to high concentration.* Energy is required in the form of ATP!endocytosis-process of taking material into thecell by means of infoldings, or pockets of thecell membranephagocytosis-when large particles are taken intothe cell by extensions of the cytoplasmsurrounding and engulfing the particleexocytosis-the removal of large amounts ofmaterial by the cell29

Diversity of Cell LifeUnicellular Organisms (Single celled) Have all 8 characteristics of life Carry out all life functions Lack cell specialization (specialized toperform a specific function).Muticellular Organisms (many cells) cells that are interdependent. All cells are specialized and work together. Have all 8 characteristics of life Carry out all life functions

Levels of OrganizationMost complexOrganismOrgan Systems: Groups oforgans working together toperform a specific function(Digestive, Nervous, CirculatoryOrgans: Groups of tissues that worktogether (Heart, Lungs, kidneys)Tissues: Groups of similar cells that perform aspecific function; 4 Types (muscle, epithelial,nervous, connective (bone, blood, cartilage)Least complex Cells: Perform a particular function

Chapter 7 Cell Structure & Function 1. The Cell Theory 1. All living things are made up of cells. 2. Cells are the basic unit of structure & . membrane a tough, flexible structure; forms a barrier between cell & its surroundings. Cell Membrane Protein Channels & Pumps: embedded in