Presentation on theme: "Basic Unit of Life: The Cell"— Presentation transcript:
1 Basic Unit of Life: The Cell Chapter 3Basic Unit of Life: The Cell
2 All Organisms are made up of cells Eukaryotes-MothJuniperProtozoansCiliates in water onplantProkaryotesBacteria in insect gutand on surface ofinsect and tree
3 Cell theory All living organisms are made up of cells All cells come from other cellsTheory refers to the body of knowledge that has been developed through scientific inquiryHuman body has 60 trillion cells that all started from a single fertilized egg. How many divisions is that? Elephant bird extinct in 1600’s Madagascar
4 Two Cell Categories Prokaryote Eukaryote Cell membrane Cytoplasm DNA (in a loop)Ribosomes (for creating proteins)Cell wallVery smallDNA is loose in cytoplasmCell membraneCytoplasmDNA (in strands)RibosomesMany other organellesCell wall in plantsVariable size – larger than prokaryotesNucleus holds DNAGreek for before kernel and good kernel; Prokaryote cells were first type to evolve. Eukaryotes evolved from prokaryote cells. We’ll learn more about prokaryotes later in course.
5 The organisms that cause colors in the hot springs of Yellowstone are single celled and have been around since the beginning of life on this planet. Would these organisms be prokaryotes or eukaryotes? Would their cells have a nucleus?A. Prokaryotes, yes B. Prokaryotes, no C. Eukaryotes, yes D. Eukaryotes, no meheat/yellowstone.html
6 Basic Cell Structures Cell Membrane Nuclear double membrane around nucleusMitochondria for energyProcessing and packaging organellesLysosomes – digestionCytoskeleton - supportEukaryote
7 Plasma MembranesSeparates cell from its environment so it can have reactions that are different and controlled.
9 Molecules Found in the cell Membrane Cholesterol increases membrane flexibilityTertiary structure of proteins important part of holding them in a certain position in the membrane.
10 Types of Membrane Proteins 1. Receptor proteins –Bind to external molecules which cause reactions in cellEx. Target cells can detect hormones in blood – regulate development of secondary sexual characteristics2. Recognition proteinsTypically have attached carbohydrate chainsGive the cell identity – other cells can recognize themEx. During development cells interact & work together to develop structures. Recognition is essential.Ex. Autoimmune disease = faulty self-recognition1. Heart rate and adrenaline; 2. immune response and id’ing self
12 Types of Membrane Proteins 3. Transport proteinsMove other molecules across the cell membraneTransmembrane proteins onlyEx. Nerve cell fire – Na ions moved across4. Enzymatic proteinsIncrease rate of chemical reactions associated with the cell membraneEx. cAMP formation regulated – internal messenger created
13 Visual Examples Transport proteins Enzymatic proteins Can have proteins working together – recognition of hormone – triggers enzymatic protein action within cell. Animation – have set up.
14 Why is the cell membrane considered a fluid mosaic? It’s primarily made up of water with dispersed fats and proteins in a mosaic patternProteins move back and forth through the membrane from inside to outside of the cell and back in a fluid mosaic pattern.It’s made up of several different types of molecules, like a mosaic, and many of those molecules float around in the lipid bilayer.
15 Cell Structure and Function Cells are factoriesNeed raw materials to enter the cellNeed to eliminate wastesNeed to export products produced in the cellNeed to keep up-to-date on needs of surrounding cells and tissuesCell membrane is very busy
16 EndocytosisPhagocytosis = endocytosis of large particles or other cells
19 Animation of endocytosis and exocytosis hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535 ::535::/sites/dl/free/ /120068/bio02. swf::Endocytosis%20and%20Exocytosis
20 Other means of movement Passive TransportActive TransportRequires no input of energyDiffusionOsmosis (diffusion of water across a membrane)Requires energy input to move molecules across the cell membrane or around in the cellPrimary – uses ATPSecondary
21 Diffusion Key: Molecules tend to move from an area of high concentration to an area oflow concentrationWhen moving across a membrane – diffusion may be facilitated by a transport proteinWhy is water a good solvent
23 Irrigation problems Irrigation can lead to a build up of soil salinity If soil develops a similar (or higher) salt content than the plant cells, water doesn’t flow as easily into plant roots.Soil salt concentrations make plants and soil more alike in fluid concentration (isotonic) - so water doesn’t flow across the cell membranes into the plant roots.Soil salinity creates drought like conditions in which plants can’t get waterWestern Montana has this problem.
25 Active TransportAcidity of stomach increases when you eat. pH can drop from 3-4 to as low as 1.
26 The object depicted in the figure: A) is a bacterial cell. B) could be either a plant or an animal cell. C) is a ribosome. D) is an animal cell. E) is a plant cell.
27 Cell Wall Not found in animals A major component of the cell wall is the complex carbohydrate, Cellulose
28 If the concentrations of a particular molecule are equal on both sides of the membrane, facilitated diffusion will:A) insure that the molecule becomes concentrated outside the cell. B) insure that the molecule stays impermeable to the membrane. C) insure that the molecule becomes concentrated inside the cell. D) insure that the concentrations inside and outside the cell are both increased. E) be ineffective.
29 Connections Between Cells: 1 Connections Between Cells: 1. Tight Junctions > hold cells in place > keep fluids from passing around edges of cells blood brain barrier lining of gut
30 Connections Between Cells: 2. Desmosomes > throughout body
31 Connections Between Cells: 3 Connections Between Cells: 3. Gap Junctions >Allows small molecules, but not large proteins and organelles to move between cells.Heart muscle
32 Why not bigger? Cell Size Chicken egg = 40-60 mm (1mm = 1/1000 m)Paramecium caudatum = 60X 230 um(1 um = 1/1000 mm)Red blood cell = umBacteria umWhy not bigger?
33 What limits the size of cells? Much of what occurs in a cell depends on the movement of materials in and out of the cell through the plasma membraneRate of production and waste removal is dependent on cell volumeRate of movement across the membrane depends on surface area of cellAs cell size increases, volume increases as a cubed unit while surface area as a square unit.
34 Surface to volume ratio Radius1 cm2 cm3 cmSurface area (cm2)12.5750.26201.06Volume (cm 3)4.1933.51268.08SA/V31.50.75Eggs can get large because much of activity is dormant (yolk is just stored material) and cell is not requiring materials for synthesis and does have waste materials to eliminate. As soon as fertilized, it starts to divide – increasing surface area rapidly.
38 Microfilaments underlie the cell membrane and cytoskeletal elements can break down and reform to allow changing shape in Amoeba.
39 Cell locomotion:Protein microtubules and filaments have function in locomotion as well as cell shape and transport.
40 Mitochondria – have own DNA! Free ribosomes in matrix (like bacteria) Circular DNA present. Mitochondria divide independently of cell. Folds of inner membrane = cristae (sing: crista)
41 Mitochondria con’t Number in a cell may vary Cells with high energy demands likemuscles have more than other cellsProcess known as aerobic respiration (Kreb cycle & electron transport phosphorylation) takes place here.Sugar (C6H12O6) + 6H2O + 6O2 => 6 CO water (H2O) + EnergyBreaks down sugar to release the energy in the chemical bondsOxygen is used and Carbon dioxide is a waste biproduct.
42 Chloroplasts Only in Plant Cells and Single-celled Algae Have own DNA! Similar in some ways to bacteria that do photosynthesis – especially DNA
43 Evolution of Eukaryote Cells Why they have double membranes around the outside and their own circular DNA like bacteria. Play animation about organelle evolution.
44 Lysosomes – Waste removal Produced by ER and Golgi apparatus. Filled with enzymes. Fuse with vesicles containing waste and enzymes break down to components that are recycled in the cell. Rest is eliminated by exocytosis. (Microbodies are sacs of enzymes that transform products from the Golgi body into other molecules and transport these to where they are needed)Up to 50 different types of enzymes!
51 Cells can be Single-celled Organisms Euglena can engulf other organisms or do photosynthesis to get food for building blocks and energy.EyespotFlagellumContractile Vacuole
52 Cells Specializations Within a Multicellular Organism All cells have the same genetic material.Cells specialize because some genes are turned off and others are turned on.Ex. Lining of small intestineEx. Nerve cell
53 Design Organelle Analogies AnalogyIncludes similes and metaphoresSimiles compare things using words “as” or “like”Ex. You are as stubborn as a mule.Ex. Life is like a box of chocolates.Metaphores compare 2 unlike things for secondary meaningEx. The gum was bursting with flavor.Ex. The relationship between them began to thaw.
54 The organelle in the figure is found in: A) animals only. B) plants only. C) plants, animals, and bacteria. D) plants and animals. E) bacteria only.What is it?
55 The lysosomes in a human cell contain approximately ________ different type(s) of digestive enzymes. A) 1 B) 500 C) 10 D) 4 E) 50E
56 According to the theory of endosymbiosis, the origin of chloroplasts probably involved: A) the formation of cell walls around the photosynthetic pigments. B) the formation of colonies of cyanobacteria. C) the engulfing of small photosynthetic prokaryotes by larger cells. D) the accumulation of free oxygen in ocean waters. E) All of the above are correct.
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