2Cell theoryCells are the basic living units of organization and functionAll cells come from other cellsWork of Schleiden, Schwann, and Virchow contributed to this theoryEach cell is a microcosm of life
3Cell organization and size permit homeostasis Homeostasis: The balanced internal environment of the body; the automatic tendency of an organism to maintain such a steady state.
4Cell surface area-to-volume ratio Plasma membrane must be large enough relative to cell volume to regulate passage of materials
5Organization is basically the same in all cells All cells have a plasma membrane, which is a selective barrierCells have internal organelles that are specialized for various functionsCell size is limited by the surface to volume ratio, so cells remain smallCell shape and size are related to function.
6Surface to volume ratio As the cell size increases, the volume becomes too large for the surface membrane to handle.
10Small size… (add)Molecules must be transported to the locations where they are converted into other formsWith small cell size, distances molecules travel within them are relatively short which speeds up many cellular activities
11Cells are studied by a combination of methods Robert Hooke: identified the cell walls and gave the structure the name “cell”.Study of the cell was not possible until microscopes.
12MicroscopesLight microscope, referred to as compound microscope, used by most studentsTwo features determine how clearly an object is viewedMagnification: how much largerResolution: how clearLight microscope has 500 times more resolution than human eye
13Allows study of the ultrastructure of cells Electron microscopeDeveloped in the 1950sAllows study of the ultrastructure of cells10,000 times more resolution than human eye
14Types of electron microscope Transmission electron microscope: used for studying ultra structure. Specimen must be specially prepared and sliced very thin.Scanning electron microscope: bounces electrons off a thin metallic coating on the object. Enables surface area to be viewed.
16Cell fractionation Used to determine function of organelles Cells broken apart and the resulting cell extract spun in a centrifugeCentrifugal force separates extractPellet: solid particleSupernatant: fluid material
18Types of Cells http://www. tvdsb. on Prokaryotic Cells: Bacteria and Archea1. lack membrane bound organelles2. smaller in size than eukaryotes3. DNA is located in nucleoid area and is not bound by a nuclear membrane4. Most have cell walls5. Have ribosomes and storage granules
19Eukaryotic cells: all other organisms 1. nucleoplasm: contains chromosomes which package DNA2. cytoplasm: area outside the nucleus; contains cytosol and organelles, many of which are membrane-bound3. type of cell determines which organelles are present and in what numbers
20Divide cell into compartments, allowing for specialized activities Functions of cell membranesDivide cell into compartments, allowing for specialized activitiesInteracting membranes form endomembrane systemVesicles transport materials between compartments
23The cell nucleus Contains DNA Bounded by Nuclear envelopeDouble membrane perforated with nuclear poresDNA forms chromatin, which is organized into chromosomesNucleolusRNA synthesis and ribosome assembly
25Endoplasmic reticulum (ER) Network of folded internal membranes in the cytosolSmooth ERSite of lipid synthesisSite of detoxifying enzymesRough ERRibosomes manufacture proteinsProteins may be moved into the ER lumen
28Glycoproteins transported to the cis face Golgi complexCisternae that process, sort, and modify proteinsIn animal cells, Golgi complex also manufactures lysosomesGlycoproteins transported to the cis faceGolgi modifies carbohydrates and lipids and packages into vesicles; which then may leave the cell
30Lysosomes break down worn-out cell structures, bacteria, and other substances Primary lysosomes bud from the Golgi complexSecondary lysosomes form by fusion of a primary lysosome with a vesicle containing ingested materialInvolved in apoptosis (programmed cell death)
32Peroxisomes metabolize small organic compounds Transfer hydrogen from various compounds to oxygen, forming hydrogen peroxideCatalase is an enzyme that breaks down hydrogen peroxideMost common in cells that synthesize, store, and degrade lipids
34Vacuoles Large, fluid-filled sacs with a variety of functions. May function in storage of toxins or pigmentsPlant vacuoles are typically large and allow the cell to increase in sizeProtist vacuoles may involve digestion or excretion.
37Mitochondria Sites of aerobic respiration Organelles enclosed by a double membraneCristae and matrix contain enzymes for aerobic respirationNutrients broken down and energy packaged in ATPCarbon dioxide and water by-products
39Chloroplasts Plastids that carry out photosynthesis Inner membrane of chloroplast encloses the stromaDuring photosynthesis, chlorophyll traps light energyEnergy converted to chemical energy in ATP; sugars/food for the plant are manufactured.
48Glycocalyx, cell coat formed by polysaccarides extending from plasma membrane Many animal cells also surrounded by an extracellular matrix (ECM)Most bacteria, fungi, and plant cell walls made of carbohydrates