4Compound Light Microscope Uses 1 or more lenses to produce enlarged imagesAllows you to see living cellsMagnifies up to 2,000 times
5Electron MicroscopesUse beams of electrons, similar to your televisionCan’t see living cells, because specimens are put into a vacuumMagnifies up to 200,000 times2 types
6Transmission Electron Microscope Thin slices stained with metal ionsHeavily stained portions absorb electronsLightly stained portions the electrons pass through, hitting a fluorescent screen and forming an imageBlack and white images, color added
7Scanning Electron Microscope Coated with layer of metalElectrons bounce off onto a fluorescent screen3-D black and white images, color added
8Scanning Tunneling Microscope Uses voltage differences to create digital imagesAllows you to see individual atoms in 3-DYou can see living organismsMagnifies up to 10 million times
9Cell Theory All living things are made of one or more cells Cells are the basic units of structure and function in organismsAll cells arise from existing cells
10What is a cell?All cells have all of the equipment necessary to perform the essential functions of lifeAll cells share several common featuresThere are 2 types of cells
11What features do all cells share? Cell membrane—the outer boundary that encloses the cell, protects it from its surroundings, and regulates what leave and enters, including gases, nutrients, and wastesCytoplasm—the cell interiorRibosomes—the place where proteins are madeDNA—provides instructions
12What are the two types of cells? ProkaryotesEukaryotes
13Prokaryotes The smallest and simplest cells, 1 – 15 µm Lack a nucleus and other internal compartmentsLived at least 3.5 billion years agoAn example is a bacteria
14Characteristics of Prokaryotes Grow and divide rapidlySome need O2, others don’tSome make their own foodNo internal compartments, so enzymes and ribosomes move about freelySingle, circular strand of DNACell wall
15Prokaryotic Cell WallThe cell wall is made of polysaccharides with short amino acid chains attachedProkaryotes have to have a cell wall, because they do not have an internal skeletonA prokaryote’s cell wall is to a bacteria as an insect’s exoskeleton is to an ant
16Prokaryotes’ Capsules Some prokaryotes have capsules out side of their cell wallsAllow them to cling to almost anything, like skin, teeth, and foodHow would this benefit them?
17FlagellaMany prokaryotes have flagella, long threadlike structure that protrude from the cell’s surface and enable movementThe flagella rotate to propel the prokaryote
18Eukaryotes Any organisms whose cells have a nucleus They also have other internal compartments, called organellesEvolved about 1.5 billion years ago
19Nucleus, Organelles, and Cytoplasm The nucleus is an internal compartment that houses the cell’s DNAOrganelles are other internal structures that carry out specific functions in the cellCytoplasm is everything inside thecell membrane but outside thenucleus
20Flagella and CiliaCilia are short, hair-like structures that protrude from cell surfacesFlagella and cilia can propel cells or they can move substances across a cell’s surfaceCilia in lungs sweep mucus and debris away and in your ears they conduct sound vibrations
21Cytoskeleton The cytoskeleton is a web of protein fibers It holds the cell together and keeps cell membranes from collapsingAnchored to cell membraneIt links one region to anotherAnchors nucleus and organelles to fixed locations3 different kinds—microfilaments, microtubules, and intermediate filaments
22Microfilaments Long and slender, made of actin Network beneath cell’s surface that is anchored to the membrane proteinsDetermines the shape of the cell
23Microtubules Hollow tubes of tubulin Within the cytoskeleton, microtubules act as the highway for transportation of information from the nucleus outRNA/protein complexes are transported along the “tracks” of microtubules by motor proteins
24Intermediate Filaments Intermediate filaments are thick ropes of proteinThey make up the frame that allows ribosomes and enzymes to be confined, which allows cells to organize complex metabolic activitiesefficiently
25Cell MembraneCell membranes are made up of phospholipids, which are a phosphate group and two fatty acidsPhospholipids are made up of a polar “head” and two nonpolar “tails”Phospholipids form a phospholipid bilayer
26Cell Membrane Cell membranes have selective permeability The lipid bilayer allows lipids and substances that dissolve in lipids to pass throughMembrane proteins are also part of the membrane—some are for transport
27Cell MembraneThere are several types of membrane proteins, including:Marker proteinsTransport proteinsEnzymesReceptor proteinsProteins move, because phospholipids are constantly in motion
28Nucleus Houses most of the DNA, which controls the cell’s functions Surrounded by a double membrane, called the nuclear envelope or nuclear membraneThe nuclear envelope is made of two lipid bilayersWhy do you think that there are 2?
29Nucleus Nuclear pores are small channels through the nuclear envelope What are the pores for?The nucleolus is an area of the nucleus where ribosomes are partially assembledEukaryotic DNA is tightly wound around proteins, and appears as a dark mass under magnification most of the time
30Ribosomes Made up of dozens of proteins and RNA Cells make proteins on ribosomesSome are suspended in the cytosol. These are “free” ribosomes. “Free” ribosomes make proteins that remain in the cell.Proteins that leave the cell are made on ribosomes on the surface of the endoplasmic reticulum
31Endoplasmic Reticulum An extensive system of internal membranes that move proteins and other substances through the cellThe membrane of ER is a lipid bilayer with embeddedproteins
32Rough Endoplasmic Reticulum The Rough ER has ribosomes attachedIt helps transport proteins made on the attached ribosomesThe proteins enter the ER and a small, membrane-bound sac, or vesicle, pinches offProteins made on ribosomes onthe rough ER stay separate fromproteins made on free ribosomes
33Smooth Endoplasmic Reticulum The Smooth Endoplasmic Reticulum lacks ribosomes, so it appears smooth under an electron microscopeThe smooth ER makes lipids and breaks down toxic substances
34Golgi ApparatusA flattened, membrane-bound sac that serves as the packaging and distribution center of the cellEnzymes in the Golgi Apparatus modify proteins from the ER
35LysosomesLysosomes are small, spherical organelles that contain the cell’s digestive enzymes
36MitochondriaOrganelle that uses organic compounds to make ATP, the primary energy source of cellsCells with high energy requirements, like muscle cells, may contain hundreds or thousands or mitochondria
37Mitochondria The mitochondria has two membranes The outer membrane is smoothThe inner membrane is greatly folded, so that it has a lot of surface areaThe two membranesform two compartments
38MitochondriaThe mitochondria also contain DNA and ribosomes, because they make some of their own proteinsMost mitochondrial proteins are made in the cytosol
39Organelles Only Found in Plants Plants have 3 unique organellesCell wallChloroplastsCentral vacuole
40Cell Wall Plants’ cell membranes are surrounded by cell walls Plant cell walls are made of proteins and carbohydrates, including celluloseHelps support and protect the cellsConnects cells to one another
41ChloroplastsChloroplasts are organelles that use light to make carbohydrates from CO2 and H2OFound in algae as well as plantsSurrounded by 2 membranesContain their own DNA
42Central Vacuole The central vacuole stores water It may contain ions, nutrients, and wastesIt makes the cell rigid, when it is fullEnables plants to stand upright
43Let’s ReviewWe use microscopes to look at cells that are too small to see with the naked eyeThe Cell TheoryWhat is a cell? What do all cells share?Prokaryotes vs. EukaryotesNucleus, Organelles, and Cytoplasm, oh my!What separates plants from other eukaryotes?
44The Cell contains Function as Function as Function as Function as CytoplasmRibosomes3.ER & Golgi apparatus4.5.structureSupport/6.Power Plants1.2.containsFunction asFunction asFunction asFunction asFunction as
45How did eukaryotes and prokaryotes come to be so different? Lynn Margulis
46Margulis’s Other Causal Questions Why do mitochondria and chloroplasts have their own DNA?Why do they have two membranes, when other organelles only have one?Why do these organelles reproduce separately from the rest of the cell?
47Endosymbiont TheoryMargulis proposed that billions of years ago, eukaryotic cells arose as a combination of different prokaryotic cellsThe ancestors of mitochondria and chloroplasts were once symbionts living inside larger cellsThey eventually lost their independence and became organelles
48Endosymbiont Theory The theory answered each of Margulis’s questions They have their own DNA and reproduce separately because they were once independentThe inner membrane could be a remnant of the old cell membrane and the outer membrane could be the cell’s membrane surrounding the “foreign cell”Further evidence supports Margulis’s Theory
49Why aren’t organisms made of a few large cells? The human body is made up of about 100 trillion cellsMost of our cells are from 5µm - 20µm in diameter(There are 100 µm in 1 mm)
50Surface Area-to-Volume Ratios Calculate the surface area-to-volume ratio of a cube with a side length of 2mm.Calculate the surface area-to-volume ratio of a cube with a side length of 1mm.
51Relationship Between Surface Area and Volume Side LengthSurface areaVolumeSurface area : volume ratio1 mm6 mm21 mm36 : 12 mm24 mm28 mm33 : 14 mm96 mm264 mm33:2
52Why would the surface area to volume ratio be important? How does the flatness of a single-celled Paramecium affect the cell’s surface area-to-volume ratio?How would it affect thecell’s ability to survive?