2Cell History Robert Hooke (1635-1703) Viewed slices of cork under a crude compound microscopeHe saw boxes which reminded him of cells that monks lived inHence the name “cell”
3Cell History Anton van Leeuwenhoek (1632-1723) Designed an early microscopeFirst to see living organisms in a drop of water
4Cell History Robert Brown (1773-1858) Used special stains and dye to view nucleus
5Cell History Theodor Schwann, zoologist, (1810-1882) Rudolph Virchow, physician ( )Mathias Schleiden,botanist ( )
6Cell TheorySchleiden, Schwann and Virchow each contributed to the cell theory ( ):Cells are the basic unit of structure and function of all living thingsAll living things are composed of one or more cellsNew cells are produced from existing cells
7Cell Types Prokaryotic Eukaryotic First appear in fossil record 3.5 BYANo membrane bound organellesNo NucleusBacteriaEukaryoticEvolved 1.5 BYAHave membrane bound organellesHave NucleusProtists, fungi, animals, plants
8Cell Structures Cell Membrane (AKA: Plasma Membrane) Selectively permeableRegulates what goes in and outFlexibleProvides protection and supportMade of a lipid bilayer
9Phospholipids Fatty acid tails are non-polar Heads are polar Tails don’t want to be near water because water is polar so they are inside the bilayer.
11Cellular Transportation The cell membrane is selectively permeable and allows some particles come into the cell and keeps some of them out.
122 Types of Transportation Passive Transport* The cell does not use any energy.* Materials flow down the concentration gradient from High concentration to low concentrationActive Transport* Requires that the cell use energy.* Movement of solutes against a concentration gradient from Low concentration to High concentration.
13The 3 most common types of Passive Transport: 1. Diffusion2. Osmosis3. Facilitated Diffusion
14DiffusionThe overall direction of the movement is referred to as the Gradient.In diffusion molecules usually move “down the concentration gradient”..... flow from high concentration to low concentration.A state of “equilibrium” is reached where molecules are uniformly distributed but continue to move randomly.
15Direction of Diffusion Simple DiffusionMoleculesDirection of DiffusionHigh ConcentrationLow ConcentrationSelectively Permeable Membrane
16OsmosisThe diffusion of WATER across a selectively permeable membrane is called OSMOSIS.Osmotic environments are classified by the concentration of the solutes in the solution.
17Osmotic environments are classified as: 1. Isotonic2. Hypertonic3. Hypotonic
18Isotonic EnvironmentIn an Isotonic solution, the concentration of solutes outside and inside the cell are equal.Water is moving in and out at an equal rate.95% Water5% Solutes95% Water5% Solutes
19Hypertonic Environment Concentration of solutes is greater outside the cell than inside the cell.Water will move outside the cell… the cell will shrink and die.97% Water3% solute95% Water5% solute
20Hypotonic Environment Concentration of solutes is greater inside the cell than outside the cell.Water will move inside the cell… the cell will swell, or burst, and die.95% Water5% solute97% Water3% solute
21Facilitated Diffusion The diffusion of large particles through channel proteins in the plasma membrane.Example: Glucose moves in and out of cells through Facilitated Diffusion.
22Types of Active Transport are: (Phagocytosis & Pinocytosis) Active Transport *Solutes flow against the concentration gradient. * The cell uses energy… usually ATP. *Requires Transport ProteinsTypes of Active Transport are:1. Exocytosis2. Endocytosis(Phagocytosis & Pinocytosis)
23Exocytosis (exo = outside, Cyto = cell) Moving substances outside the cell Process of vesicles fusing with the plasma membrane and releasing their content to the outside of the cell.
24Endocytosis (endo = inside, cyto = cell) The capture of substancesoutside the cell when the plasma membrane merges to engulf it.
25Phagocytosis (phago = to eat, cyto = cell) Phagocytosis occurs when undissolved solids enter a cell.The plasma membrane wraps around the solid material and engulfs it, forming a vesicle.Phagocytic cells, such as white blood cells, attack and engulf bacteria in this manner.
26Pinocytosis (pino = to drink, cyto = cell) Pinocytosis occurs when dissolved materials enter a cell.The plasma membrane folds inward to form a channel allowing the liquid to enter.The plasma membrane closes off the channel, encircling the liquid inside a vesicle.
27Cell StructuresThe cytoplasm is a jelly-like substance that holds many other organelles such as:Endoplasmic Reticulum – transports lipids and proteinsRibosomes – produce proteinsGolgi Apparatus – packages and delivers proteinsMitochondria – Transform energy into a chemical form that can be used by the cell.Lysosomes – Help with cell digestionPeroxisomes – House enzymes that speed up chemical reactions.
28Cell Structures (cont.) Microfilaments/Microtubules – form cytoskeleton to help with cell movement.Centrosome – Contains centrioles that help during Mitosis.Cilia/Flagella – Cellular extensions that aid in cell movement.Vesicles – sacs that form to help particles come into and out of the cell.
29Why are cells so small? Surface Area vs. Volume As a cell grows larger, the volume increases faster than the SAA bigger cell needs more nutrients, but has relatively less SA to take in those nutrients
30Surface Area vs. Volume Cell Size 5 cm 10 cm Surface Area (l×w×6) Volume (l×w×h)125 cm31000 cm3SA to Volume Ratio150/125 = 6:5600/1000 = 6:10
31Cell Cycle Cells divide before growing too large Before dividing, cells must preparePreparation = InterphaseG1 phase: Cell grows largerS phase: Cell makes new DNA for daughter cellG2 phase: Cell makes new organelles for daughter cell
33Chromosomes Each chromosome is replicated during the S phase CentromereSister ChromatidsEach chromosome is replicated during the S phaseA replicated chromosome has two identical sister chromatids connected by a centromere
34Mitosis Four Stages: Prophase (pro- means first) Metaphase (meta- means middle/after)Anaphase (ana- means apart)Telophase (telo- means far away/end)
35Prophase Chromatin condenses into chromosomes condensingChromatin condenses into chromosomesNuclear envelope and nucleolus disintegrateCentrioles migrate to opposite ends of the cellSpindle fibers form in foot ball shape across cell