Tour of the Cell1. Key Terms to know about he cell organellesa. organismb. cell theory c. micrograph d. organelle e. plasma membrane f. nucleus g. cytoplasm h. cell wall i. prokaryotic cell j. Eukaryotic cell
Cells - History of Discovery1. Robert Hooke (1665) - observed dead cork (wood bark)and discovered cells 2. Anton Van Leeuwenhoek (1700) - invented the compound microscope, observed living cells (saliva & blood), and discovered algae3. Matthias Schleiden - discovered that all plants and every part of them are made up of cells, discovered the cell nucleus 4. Theodor Schwann (1807-1893) -discovered that all animals and every part of them are made up of cells, independently announced that yeast is a living organism5. Rudolf Virchow (1858) -best known for his theory Omnis cellula e cellula ("every cell originates from another existing cell like it."), first to recognize leukemia cells
Cell TheorySchleiden, Schwann, and Virchow are creditedfor the cell theory. Cell Theory 1.) that all living things are composed of cells 2.) cells are the basic unit of structure 3.) cells are the basic unit of function in living things
Microscopes1.) Light- up to 1000x - living cells2.) Electron - up to 1,000,000x - dead cells a.) SEM surface structure b.) TEM internal structure
Electron Microscope1.) SEM surface structure--images using electrons are reflected fromspecimen (looks normal)-shows depth, high resolution2.) TEM internal structure--images using the electrons pass throughspecimen-silhouettes, projects fine detail on screen
Plant Cell Cell Wall Cell Membrane Golgi Vesicles Golgi Aparatus Ribosomes Smooth ER Cholorplast(Endoplasmic reticulum) Nucleolus Vacuole membrane Nucleus Rough ER (Ribosomes) Raphide Crystal Large central Druse Crystal vacuole Amyloplast Mitochondria (starch grain) Cytoplasm
Cell Wall *Only found in plant cells, *The cell wall provides the cell with additional strength. *Cell walls are thick walls built around the cell. These walls are made from cellulose.
Cell Membrane *Found in both plant and animal cells, the cell membrane is the outside wall of a cell. *In plant cells, it is a second wall, and is found just inside the main cell wall. *The cell membranes found in animal cells contain a chemical called cholesterol. This chemical makes the membrane harder. *Plant cells do not need cholesterol, because they have a cell wall, as a result, their cell membranes are softer.
Cytoplasm * Found in both plant and animal cells *Helps to hold the cells organelles (small organs) in place. *Gives the cell structure. *Helps the cell move proteins, chromosomes and other materials including the cells organelles around the cell.
Nucleus - Cell’s Brain *A cells nucleus, or brain, is responsible for directing the activities of the cell, in the same way that your brain directs the activities of your body. *Nuclear Envelope - has pores, surrounds nucleus. *In the nucleus you will see many small rod like objects called Chromosomes. They contain blueprints for how cells and organisms should be built. *The chromosomes are made from smaller molecules called DNA, and RNA (information-rich molecules) *Nucleolus contain parts that make up ribosomes.
Endoplasmic Reticulum *Found in both animal and plant cells *Clear tubes travel to all parts of the cell, known as the “Cellular Highway”. *Carries materials where they need to go. *The ER is also connected to the nuclear envelope. *Rough ER: contains ribosomes *Smooth ER: transports materials
Ribosomes *Found in both animals and plant cells *They are created in the nucleolus, which is found inside the cells nucleus *They are either suspended in the cytoplasm or temporarily attached to the rough endoplasmic reticulum (ER) *Ribosomes use available materials to build proteins. These proteins can then be used by the cell for other purposes, such as to build new structures, repair damage, and direct chemical reactions.
Moving Proteins *Some proteins are made by ribosomes (the red structure) on the rough ER and packaged in vesicles. *After further processing in other parts of the cell, these proteins will eventually move to other organelles or to the plasma membrane.
Golgi Apparatus (bodies) *Found in both plant and animal cells *Modifies, stores, and dispatch products *Takes the proteins which were created by the ribosomes, and makes them bigger and better *When the golgi apparatus is done, it releases the new proteins into the cell, where they can be used to strengthen and build up the cell.
Lysosome * Only found in animal cells *Lysosomes contain digestive enzymes that break down food for cell use. *They breakdown and digest older parts of a cell.
Membrane Pathways -how they work *Products made in the ER move through membrane pathways in a cell.
Vacuoles *Large ones found in plant cells, small ones in animal cells *This large membraned sac’s function is to store a. water & food b. waste c. undigested nutrients d. minerals e. proteins f. pigments *It helps in plant growth, and plays an important structural role for the plant.
Chloroplasts *Only found in plant cells *Small pill shaped organelle that is like a miniature “solar collector” *The discs are green because they are filled with a green pigment, or chemical called Chlorophyll that reacts with light *Chlorophyll is used by a plant to capture light energy from the sun, which transforms into chemical energy through photosynthesis to create food.
Mitochondrion *Found in plant and animal cells *responsible for energy production inside a cell * a. site of cellular respiration b. release energy from sugars c. changes ADP to ATP ( stored energy) d. ATP to ADP ( releases energy) *Cellular respiration in the mitochondria releases the energy that drives a cell. The many folds of each mitochondrions inner membrane are the sites of ATP production.
Tour of the Cell2. Key Terms to know about the Cell Membrane 1. Terms: a. phospholipid layers b. diffusion c. equilibrium d. selectively permeable membrane e. passive transport f. facilitated diffusion g. osmosis h. hypertonic i. hypotonic j. isotonic k. active transport l. vesicle m. exocytosis n. endocytosis 2. Structure of Cell Membrane
Moving through the cell membrane *A cells plasma membrane contains a diversity of proteins that drift about in the phospholipid bilayer. *Even the phospholipid molecules themselves can move along the plane of the fluid-like membrane. *Some membrane proteins and lipids have carbohydrate chains attached to their outer surfaces.
Transport- Diffusion Dye molecules diffuse across a membrane. At equilibrium, the concentration of dye is the same throughout the container.
Passive Transport Both diffusion and facilitated diffusion are forms of passive transport, as neither process requires the cell to expend energy. In facilitated diffusion, solute particles pass through a channel in a transport protein.
Osmosis OSMOSIS IS DIFFUSION OF WATER FORM REGION OF LESSER CONCENTRATION OF SOLUTE TO GREATER CONCENTRATION OF SOLUTE UNTIL EQUILIBRIUM OCCURS A selectively permeable membrane (the bag) separates two solutions of different sugar concentrations. Sugar molecules cannot pass through the membrane.
Active Transport Like an enzyme, a transport protein recognizes a specific solute, molecule or ion. During active transport, the protein transport uses energy, usually moving the solute in a direction from lesser concentration to greater concentration.
Transport of large molecule Active transport plays a part in maintaining the cells chemical environment. Pinocytosis- Pino= drink (liquid) Phagocytosis- Phago= eat (solid) Exocytosis (top left) expels molecules from the cell that are too large to pass through the plasma membrane. Endocytosis (bottom left) brings large molecules into the cell and packages them in vesicles.
The cell theory never states that cell must be small.But, there are two reasons given for their size:1. Efficiency- surface area is increased. Cells requirenutrients and oxygen to get rid of waste and must moveacross the membrane to do so. If the cell were too big,these nutrients and wastes would have to cover largedistances in order to get to the proper destination insidethe cell.2. Specialization- having numerous small cells permitsspecialization and different cells have differentfunctions.
Prokaryotic CellThese are the simplest of all cells.Most only have a cell wall and ribosomes.1. DNA loop- naked in the cytoplasm, whichcontains all genetic info(processes)2. Ribosomes- freely floating in thecytoplasm for protein synthesis(antibiotics,like tetracycline, bind to ribosome andinterfere with protein synthesis)3. Plasmids- contain small loop ofextrachromosomal DNA
Prokaryotic Cell4. Cell Wall- gives shape and protection fromunfavorable outside environment for cell membraneTwo types of cell walls that classify bacteria:Gram Positive- contain a thick peptidoglycan(protein-carbohydrate mix) layer and no outer membrane layerGram Negative- have a multilayered and complex wallmade of an outer lipopolysaccharide and thinpeptidoglycan inner layerAntibiotics like penicillin inhibit cell wall development, which preventsreproduction of the prokaryotic cell.Enzymes in tears, mucus, and saliva dissolve the cell wall, rupturing the cell andkilling the bacteria.
Prokaryotic Cell5. Capsule- a jelly-like coating that surround the cellwall; there are four functions of the capsule:1. prevents from drying out2. helps cells stick together on other surfaces3. helps slide on surfaces4. defense mechanism from being destroyed by host organisms’ cells6. Flagella- can be one or many; provide locomotion byspinning like a propeller; they are structurally differentfrom plant/animal flagella7. Pili- short bristle-like appendages that have twofunctions:1. attach to surfaces2. assist in the transfer of DNA from one to another
Prokaryotic CellEubacteria Shapes:1. Coccus- spherical shape allows for lessdistortion in a dried out environment2. Bacillus- rod shape has more surface area totake up more nutrients from the environment3. Spirillium- spiral shape4. Spirochete- spiral shape with flagella5. Vibrio- 1/2 spiralSpiral shapes are very motile, they move using acorkscrew type of movement.
Prokaryotic CellMovement is by way of something calledchemotaxis.Chemotaxis is the movement of an organismtowards or away from a chemical. Chemicalsinfluence the organism to move toward themare called attractants (positive chemotaxis) oraway from them are called repellents(negative chemotaxis).
Prokaryotic CellSurvivalWhen environmental conditions are unfavorable,bacteria will become inactive.Some species form endospores in which a thickwall forms around the genetic material and therest of the cell disintegrates.Endospores are dormant and do not reproduceor show any signs of life, withstanding theharshest of environmental conditions.When conditions improve, endospores germinateand form an active cell again.
Prokaryotic CellReproduction1. Asexual fission- single loop of DNA is copied andthe cell splits in half by pinching between the two DNAloops.2. Sexual conjugation- a bridge is formed between twocells using pili. Requires the F plasmid (F for fertility)and controls the formation of the F pilus. If the cellcontains this plasmid, it is an F+ cell and can give anF- cell these genes, thus making it an F+ cell.R plasmids contain the genes for making a cellresistant to antibiotics and must integrate into mainDNA of cell to make it resistant.
Reproduction cont.Transformation- living bacteria absorb thegenetic material of a dead or naked geneticmaterial in the environmentTransduction- transfer of DNA from a host toanother cell by means of a virus. Virusesare non-living, pieces of DNA or RNAenclosed by a protein coat that can infectbacteria. Their DNA is small and containsinformation for making proteins involved ininfection.
Metabolic DiversityHeterotroph- dependent on outside sources of organic moleculesPhotoheterotrophs- can use light to produce ATP but must obtain carbonfrom another sourceChemoheterotrophs- most bacteria assume this metabolism, there are threetypes:Saprobes- decomposers that absorb the nutrients from dead or decayingorganic matterParasites- absorb nutrient from the body fluids of living hostsPhagotrophs- ingest food and digest it enzymatically within cell ormulticellular bodiesAutotrophs- synthesize organic molecule from inorganic substancesPhotosynthetic- harness light energy to drive organic compounds from CO2and use an internal membrane system with light absorbing pigmentsChemosynthetic- use energy from specific inorganic substances to produceorganic substances from CO2Chemoautotrophs- need only CO2 as their carbon source and obtainenergy from by oxidizing inorganic nutrients like H2S, NH4, Fe2O3; a uniquegroup for prokaryotes
O2 RequirementsOxygen requirements also helps classifyprokaryotic organisms:1. Obligate aerobes- must need and useoxygen for cellular respiration- cannot bewithout it2. Facultative anaerobes- will use oxygen ifpresent, but can grow by fermentationwithout oxygen3. Obligate anaerobes- cannot use oxygenand are killed by the presence of it
ArchaebacteriaPrimitive forms of modern day bacteria thatare thriving in different environmentconditions1. Methanogens- use hydrogen to reduce CO2 into methane; are obligateanaerobes that live in swamps, marshes and the guts of animals likecows, sheep, and camels; are used as important decomposers in sewagetreatment plants2. Extreme Halophiles- like high salinity (salt) environments; this can colorwater pink because of their photosynthetic pigment bacteriorhodopsin3. Thermoacidophiles- need an environment that is hot (140-180 degreesfahrenheit) and acidic (pH of 2-4), they have no cell wall and can growaerobically or anaerobically; examples are hot springs, water heaters, andcoal piles