2Cell Size, Microscopes, and The Cell Theory UNIT 4 CHAPTER 3Section 1:Cell Size, Microscopes, and The Cell Theory
3Cells and Cell Size The cell is the basic structural and functional unit of all known livingorganisms. The cell is the smallestunit of life that is classified as aliving thing, and is often called thebuilding block of life.Most cells are much smallerthan a grain of sand.Cells and cell structures are measured in incredibly small metric units called ‘micro’ and ‘nano’ meters.Cells are only visible with either light microscopes or electron microscopes.
4What limits the size of cells? Surface area to volume ratios must be small so substances can move in, move out, and move throughout the cell easily and rapidly.This limits the largest of cells in your body to about 20 micrometers, or about 1/3 the width of a human hair.
6Compound Light Microscopes A compound light microscope uses two lenses to focus light and magnify an image on a transparent slide.A compound light microscope magnifies images up to 2,000 times.4X Scanning Objective Lens(Ocular lens)10X Low Power Objective Lens40X High PowerDiaphragm
7Transmission Electron Microscopes A transmission electron microscope operates in a vacuum and uses a stream of electrons to bombard a metal stained specimen, creating a fluorescent computer image.It allows all but the smallest cell structures to be viewed (magnifies up to 200,000 times).
8Scanning Tunneling Microscopes Scanning tunneling microscopes utilize a needle-like probe to tract voltage differences caused by electrons which ‘leak’ or ‘tunnel’ from the object being viewed.
10The Cell TheoryThe cell theory was developed in the mid- 1800s, and was the work of several scientists over many years.The major scientists that contributed to the cell theory were:1665 – Robert Hooke – first used the name ‘cell’ after observing structures in cork1674 – Anton van Leeuwenhoek – improved the microscope and observed living cells
11The Cell Theory1838 – Matthias Schleiden – discovered that plants were composed of cells1839 – Theodor Schwann – discovered that animals were composed of cells1855 – Rudolph Virchow – proposed a theory that every cell comes from another living cellThe observations of scientists such as Schleiden, Schwann, and Virchow led to the development of The Cell Theory.
12The Cell Theory The cell theory states: All living things are composed of one or more cells.Cells are the basic units of structure and function in all organisms.New cells are produced only from existing cells (cells divide, or replicate).
13Types of Cells, Cytoskeleton, Cell Membranes, and Membrane Proteins UNIT 4 CHAPTER 3Section 2:Types of Cells, Cytoskeleton, Cell Membranes, and Membrane Proteins
14Prokaryotes and Eukaryotes Cells are classified based on their structure and the way they obtain energy.Cells are classified as either prokaryotes or eukaryotes.
15Examples: staph, E. coli, strep, bacteria Prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles.Most prokaryotes are unicellular, but a few types have multicellular stages in their life cycles.Characteristics:Prokaryotes have no nuclear membrane -- the genetic material is dispersed throughout the cytoplasm.They have no membrane-bound organelles.Most prokaryotes have a cell membrane, cytoplasm, and cell wall. They do not have a nucleus, mitochondria, or chloroplasts.ProkaryotesExamples: staph, E. coli, strep, bacteria
17All cells in multi-cellular organisms are eukaryotic. A eukaryote is an organism whose cells contain complex structures enclosed within membranes.Eukaryotes are generally more complex and larger than prokaryotes.Characteristics:They have a distinct nucleus and nuclear membrane surrounding genetic material.They have numerous membrane-bound organelles.Eukaryotes have a larger, more complex internal structure than prokaryotes.Examples: plants, animals, protists, and fungiEukaryotesAll cells in multi-cellular organisms are eukaryotic.
18Eukaryotic Cells are More Complex than Prokaryotic Cells Animals, plants, protists, and fungi are all eukaryotes and have a cell membrane, nucleus that contains DNA, cytoplasm, and mitochondria.Plants and fungi also have a cell wall, but eukaryotes do not. Only plants have chloroplasts.Flagella and cilia (short, hair-like structures used for movement) are a common features among single-celled eukaryotes.
20Plant Cells and Animal Cells There are some key differences between plant cells and animal cells.In addition to a cell membrane, plant cells have a rigid cell wall composed of cellulose which provides structure and protection.
21Plant Cells and Animal Cells Plant cells also contain unique organelles called chloroplasts which use sunlight, carbon dioxide, and water to make carbohydrates (sugars) in a process called photosynthesis.
22Plant Cells and Animal Cells Plant cells contain a large membrane bound central vacuole which takes up the vast majority of the cell volume.The central vacuole is used for storage in plant cells, and contains mostly water and other minerals.Turgor pressure is the pressure caused when a full central vacuole presses the cytoplasm against the cell wall, creating rigidity that allows plants to stand upright.
25Types of Cells nerve cell red and white blood cells muscle cells with nerve cell attachedred and white blood cellsnerve cell
26All Cells have several common structures: Cell StructuresAll Cells have several common structures:1. Cell membranethe protective layer around all cells that give the cell shape and supportAnimal CellPlant Cell
27the watery gel-like fluid that fills the inside of the cell Common Structures2. Cytoplasmthe watery gel-like fluid that fills the inside of the cellAnimal CellPlant Cell
28Common Structures 3. DNA or genetic material controls cell functions and carries hereditary informationAnimal CellPlant Cell
29the site where proteins are made Common Structures4. Ribosomesthe site where proteins are madeAnimal CellPlant Cell
30Inside The Eukaryotic Cell The cytoskeleton provides the interior framework of an animal cell and is composed of an intricate network of protein fibers anchored to the inside of the plasma membrane.
31The Cytoskeleton There are three kinds of cytoskeleton fibers: (1.) Actin fibers – form a network just beneath the cell surface that is anchored to the membrane proteins embedded within the cell membrane.Actin fibers help determine the shape of an animal cell by pulling on the plasma membrane.
33Three Kinds of Cytoskeleton (2.) Microtubules – are within the cytoskeleton and act as a transportation system for information from the nucleus to different parts of the cell. RNA is also transported along microtubules.(3.) Intermediate fibers – provide a frame on which ribosomes and enzymes can be confined to a particular region of the cell. The cell can organize complex metabolic activities efficiently by anchoring particular enzymes near one another.
34ABOVE: The eukaryotic cytoskeleton ABOVE: The eukaryotic cytoskeleton. Actin filaments are shown in red, microtubules in green, and the nuclei are in blue.
35Click on Amazing Cells, and then Directing Traffic: How Vesicles Transport Cargo.Scroll down to Vesicles Travel Cellular Highways to learn more about travel along the microfilaments.
36The Cell MembraneThe cell membrane is the outer boundary of the cell which is selectively permeable to certain substances.This selective permeability is caused mainly by the way phospholipids interact with water.A phospholipid is a lipid made of a phosphate group and two fatty acids.
38How Things Pass Through The Cell Membrane In a cell membrane, the phospholipids are arranged in a double layer called a lipid bilayer.Polar water molecules, both inside and outside the cell, repel the nonpolar fatty acid tails, forcing them to the inside of the lipid bilayer.
39How Things Pass Through The Cell Membrane Ions and most polar molecules, including sugars and some proteins, are repelled by the nonpolar interior of the lipid layer.The lipid bilayer allows lipids and substances that dissolve in lipids to pass through.
40Polar MoleculesPolar molecules have a slightly negative charge at one end, and a slightly positive charge at the other end.
41Attractions Between Molecules Because of the unequal pull of electrons exhibited by polar molecules, they have a tendency to attract one another.Non-polar molecules do not attract one another as much, and therefore exhibit different properties.Water molecules pic/ oil water pic
42The nonpolar part of a membrane protein is attracted to the interior of the lipid bilayer, but is repelled by the water on either side of the lipid bilayer.In contrast, the polar parts of the protein are attracted to the water on either side of the lipid bilayer.This attraction helps to hold the protein in the lipid bilayer.
44Three Forms of Transport Across the Membrane The Plasma Membrane4/12/2017Three Forms of Transport Across the MembraneG. Podgorski, Biol. 1010
45Membrane ProteinsReceptor proteins, marker proteins, channel proteins, transport proteins, carrier proteins, and enzymes are all part of the cell membrane.transport proteinreceptor protein
46Receptor proteins recognize and bind to substances outside the cell. Marker proteins attached to a cell’s surface advertise cell type.Transport proteins (channel proteins, carrier proteins) help substances move across the cell membrane.Enzymes are a type of protein that assist in the chemical reactions inside the cell.
50Parts of the Animal Cell Cell MembraneThe cell membrane, or plasma membrane, is the outer layer that surrounds a cell.It allows food, water and gases into the cell while allowing waste to leave the cell.The cell membrane is found in both plant and animals cells.
51Parts of the Animal Cell Cell MembraneThe cell membrane is made up of a lipid bilayer (two layers).A lipid bilayer is a thin membrane made of two layers of lipid molecules.These membranes are flat sheets that form a continuous barrier around the cell.
52The Lipid BilayerThe lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be.
53Cell Membrane The polar heads are hydrophilic -- “water loving.” The nonpolar tails are hydrophobic -- “water fearing.”This makes the membrane “selective” in what crosses into and out of the cell.
54Parts of the Animal Cell CytoplasmCytoplasm is the thick, clear, gel-like fluid that holds all the other organelles in place.Cytoplasm is between the cell membrane and the nucleus.
55Parts of the Animal Cell The NucleusThe nucleus is the “control center,” or nerve center of the cell that contains the cell's hereditary information and controls the cell's growth and reproduction.The nucleus is the largest cellular organelle in animals.
56Parts of the Animal Cell The NucleusThe nucleus has three major parts:The nuclear pores are protein complexes that allow the transport of water-soluble molecules across the nuclear envelope.The nucleolus is the home of the transcription of ribosomal RNA.The nuclear membrane is a double lipid bilayer that encloses the genetic material in eukaryotic cells.
57MitochondriaMitochondria are the cell’s power sources that function in the conversion of the potential energy of food molecules into ATP.Mitochondria are membrane-enclosed organelles distributed through the cytosol of most eukaryotic cells.Mitochondria are found in cells that use a lot of energy, such as muscle cells.cristae – folded membranes which are the sites of chemical reactions that convert food molecules into ATP
58Golgi ApparatusThe Golgi apparatus is a system of membranes that modifies and refines proteins built in the endoplasmic reticulum and prepares them for export outside of the cell, or for transport to other locations in the cell.Proteins are modified according to where in the cell they will be sent and their role in the cell.The Golgi apparatus is often considered the “distribution and shipping department” for the cell's chemical products.
64Parts of the Animal Cell LysosomesLysosomes are organelles that contain digestive enzymes (acid hydrolases). They are the cell’s “recycling bin.”Lysosomes digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.
65Parts of the Animal Cell CentriolesCentrioles are a pair of cylindrically-shaped organelles that organize the mitotic spindle and help regulate cell division.Centrioles are found in most eukaryotic cells, and are usually absent in plants and most fungi.A centriole is made of 9 sets of centrosome triplets.
66Rough Endoplasmic Reticulum The rough endoplasmic reticulum is the transport system that consists of a series of tubes and membranes that moves materials, (water, protein, oxygen and food) throughout the cell.The rough endoplasmic reticulum is covered in ribosomes, which are organelles that produce proteins needed to perform tasks.
67Smooth Endoplasmic Reticulum The smooth endoplasmic reticulum does not have ribosomes attached to its surface, and functions in the regulation of several metabolic processes.For example, the smooth endoplasmic reticulum aids in the synthesis of lipids and steroids, metabolism of carbohydrates, regulation of calcium concentration, drug detoxification, attachment of receptors on cell membrane proteins, and steroid metabolism.
68Ribosomes Ribosomes are the places where cells make new proteins. Most ribosomes are scattered throughout the cytoplasm, and others are attached to the surface of the rough endoplasmic reticulum.Unlike most organelles, ribosomes are not surrounded by membranes.Ribosomes are made up of proteins and RNA that are bound together.
69white blood cell chases bacteria on You Tube white blood cell chases bacteria on You Tube
70FLUID MOSAIC CELL MEMBRANE VIDEO FLUID MOSAIC CELL MEMBRANE VIDEOPODCAST OF CELL ORGANELLESBILL NYE CELLULAR HAZESCIENCE TEACHER RAPS ABOUT CELL ORGANELLESINTRODUCTION TO CELLS IN 3-D
71CELLS, CELLS…THEY’RE MADE OF ORGANELLES CELLS, CELLS…THEY’RE MADE OF ORGANELLESTHREE GIRLS SING CELL RAP REALLY WELLPROKARYOTE/EUKARYOTE SONG
72…so which parts of a PLANT CELL make it so different? Additional Parts of the Plant Cell…so which parts of a PLANT CELL make it so different?
74Cell Organelles Found Only in Certain Eukaryotic Cells Cell WallThe cell wall is the rigid outer wall that gives plants additional shape and support.The cell wall has tiny pores that allow materials to enter and exit.The cell wall is found in plant cells, bacteria, some protists, and fungi.
75Cell Organelles Found Only in Certain Eukaryotic Cells ChloroplastsChloroplasts are the organelles where photosynthesis occurs.Chloroplasts contain the green pigment chlorophyll that traps the energy of sunlight and makes plants green.Plants and some protists such as algae contain chloroplasts.
76Vacuoles Cell Organelles Found Only in Certain Eukaryotic Cells Vacuoles are sacs that store water and dissolved materials.In plants, there is one large central vacuole.In animal cells, smaller vacuoles are spread out in the cell.The turgor pressure from the liquid-filled vacuole allows plants to support heavy structures such as leaves and flowers.
77Plasmodesmata in Plant Cells Plasmodesmata are narrow channels that act as intercellular cytoplasmic bridges that are found in the cell walls of plants.Plasmodesmata function to facilitate communication and transport of materials between plant cells.Plasmodesmata
81Organelles of the Plant Cell - - REVIEW MitochondriaLysosomesNucleusGolgi ApparatusRough Endoplasmic ReticulumSmooth Endoplasmic ReticulumCell MembraneCell Wall
82Flagella Special Structures for Movement Flagella are long, thread-like appendages which provide some live single cells with the ability to move.Bacteria which have flagella are either rod or spiral-shaped.Cocci, or round bacteria, are almost all nonmotile.Animal sperm cells also have flagella.The flagella in prokaryotic cells such as bacteria are made of a different proteins than those of eukaryotic cells.
83Special Structures for Movement CiliaCilia are tiny tubes on single-cell organisms that use wave-like hairs to move the cell around, or can be used to move something around in the cell of a multicellular organism.Cilia are responsible for such things as protecting us from germs in our lungs and pushing an ovum down the fallopian tube.Single-celled organisms use cilia to move through liquid.
84The Endosymbiotic Theory Prokaryotic cells lack organelles bound by membranes. Mitochondria and chloroplasts have their own DNA. The DNA in the nucleus does not instruct the cell to make mitochondria or chloroplasts. The endosymbiosis theory proposes that some early prokaryotes evolved internal cell membranes which eventually led to the development of primitive eukaryotic cells.
85The Endosymbiotic Theory The theory goes on to say that other prokaryotic organisms then entered the primitive eukaryotic cell and lived inside. The eukaryotic cell formed a mutualistic relationship with the prokaryotes, one in which each organism benefits from the other.
86Over time, those prokaryotes evolved into the cell organelles of the modern eukaryotic cell. It is believed to be the means by which such organelles as mitochondria and chloroplasts arose within eukaryotic cells.
87The Endosymbiosis Theory Endosymbiosis is a type of symbiosis in which one organism lives inside the other, and the two typically behave as a single organism.It is believed to be the means by which such organelles as mitochondria and chloroplasts arose within eukaryotic cells.
88Organelles in Both Plant and Animal Cells PLASMA MEMBRANE- phospholipid bilayer barrier between outside and inside of cell- semi-permeable – made of phospholipids and proteinsNUCLEUS- control center of cell- contains instructions for making proteins- houses chromatin (blue prints) or strands of DNANUCLEOLUS- assembles ribosomes from subunits- found inside the nucleusNUCLEAR ENVELOPE (MEMBRANE)- protects the DNA from the rest of the cell’s contents made of a phospholipid bilayer with nuclear pores instead of proteinsROUGH ENDOPLASMIC RETICULUM (RER)- covered in ribosomes (appears rough)- the ribosomes are the location where proteins are made- folded membrane that continues off of nuclear envelopeSMOOTH ENDOPLASMIC RETICULUM (SER)- no ribosomes present (appears smooth)- produces and store lipids and carbohydratesCYTOPLASM- clear jelly-like fluid that suspends the organelles and ismade mostly of water
89Organelles in Both Plant and Animal Cells RIBOSOMESorganelles that makes proteins according to the directions of the DNA - ribosomes are not bound by a membranecan be found on the rough endoplasmic reticulum, or loose in the cytoplasmGOLGI APPARATUS (or GOLGI BODY)- modify and sorts proteins from the rough endoplasmic reticulum, loads them into vesicles, and sends them to destinationsVESICLES- sacs that form around and transport substances such as proteins (enzymes), lipids (steroids) and carbohydrates to specific locationsCYTOSKELETON (MICROTUBULES, MICROFILIMENTS)- the framework or backbone of the cell – supports the cell shape, anchors the organelles, provides highway system for cellular materialsMITOCHONDRIA- provides energy to the cell by breaking down glucose- Mitochondria take in oxygen and release ATP, and are numerous in muscle cells.VACUOLES- compartment that serve as temporary storage of materialsPLANTS – one big vacuole ANIMALS – many small vacuoles
90Organelles of the Animal Cell ONLY CILIA / FLAGELLACilia – short hairs that work like oars on a row boatFlagella – one or two long tails, whips back and forthboth provide movement (protista and sperm cells)CENTRIOLEplay an important role in cell division (guide the chromosomes to the proper places)Organelles of the Plant Cell ONLYCELL WALLLarge central vacuolerigid structure outside the cell membraneprovides structure/support for plants, fungi & bacteria – made of cellulose, porous, not selectiveare sacs that store water and dissolved materials. Plants have one large central vacuole, animals have several smaller vacuoles.PLASTIDS(CHLOROPLAST,CHROMOPLAST, AMYLOPLAST)Chloroplast – location of photosynthesis, contain chlorophyllChromoplast – contain carotenoids, yellow to red colorAmyloplasts – no pigments, clear, store starch grains