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Cell Structure and Function Cells Smallest living unit Most are microscopic.

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Presentation on theme: "Cell Structure and Function Cells Smallest living unit Most are microscopic."— Presentation transcript:


2 Cell Structure and Function

3 Cells Smallest living unit Most are microscopic

4 Discovery of Cells Robert Hooke (mid-1600s) –Observed sliver of cork –Saw “row of empty boxes” –Coined the term cell

5 Cell theory (1839)Theodor Schwann & Matthias Schleiden “ all living things are made of cells” (50 yrs. Later) Louis Pasteur “all cells come from cells”

6 Principles of Cell Theory All living things are made of cells Smallest living unit of structure and function of all organisms is the cell Cells carry out the functions needed to support life. All cells arise from preexisting cells (this principle discarded the idea of spontaneous generation)

7 Why study cells? Cells  Tissues  Organs  Bodies –bodies are made up of cells –cells do all the work of life!

8 The Work of Life What jobs do cells have to do for an organism to live… –“breathe” gas exchange: O 2 in vs. CO 2 out –eat take in & digest food –make energy ATP –build molecules proteins, carbohydrates, fats, nucleic acids –remove wastes –control internal conditions homeostasis –respond to external environment –build more cells growth, repair, reproduction & development ATP

9 Cell Size

10 Characteristics of All Cells A surrounding membrane Cytoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA

11 Cell Types Prokaryotic Eukaryotic

12 Two Types of Cells Prokaryotes First cells to evolve No nucleus Hereditary info is contained within cytoplasm Ex. Bacteria Eukaryotes Evolved from Prokaryotes Have a nucleus Hereditary Info is contained within the nucleus Ex. Plants, Animals, Fungi

13 Prokaryotic Cells First cell type on earth Cell type of Bacteria and Archaea

14 Prokaryotic Cells No membrane bound nucleus Nucleoid = region of DNA concentration Organelles not bound by membranes

15 Bacterium Shapes

16 Eukaryotic Cells Nucleus bound by membrane Include fungi, protists, plant, and animal cells Possess many organelles Protozoan

17 Representative Animal Cell

18 Representative Plant Cell

19 Organelles Cellular machinery

20 Cell Walls Found in plants, fungi, & many protists Surrounds plasma membrane Made of cellulose Is rigid Provides support and protection for the cell

21 Cell Wall Differences Plants – mostly cellulose Fungi – contain chitin

22 Cell membrane Surrounds all cells In a plant cell, it lies beneath the cell wall – In animal cells, it is the outer boundary (made of cholesterol) Lipid bilayer with embedded proteins Provides cell with – Protection Control of movement of materials in/out of cell Support

23 Cytoplasm Viscous fluid containing organelles components of cytoplasm –Interconnected filaments & fibers –Fluid = cytosol Found in both plant and animal cells Located beneath cell membrane Supports and protects cell organelles

24 Organelles Functional components within cytoplasm

25 Nucleus Function –control center of cell –protects DNA instructions for building proteins Structure –nuclear membrane –nucleolus ribosome factory –chromosomes DNA

26 Hereditary material Chromosomes

27 Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes

28 Endoplasmic Reticulum Helps move substances within cells Network of interconnected tubes Two types –Rough endoplasmic reticulum –Smooth endoplasmic reticulum

29 Rough Endoplasmic Reticulum Ribosomes attached to surface –Manufacture proteins –Not all ribosomes attached to rough ER

30 Smooth Endoplasmic Reticulum No attached ribosomes Has enzymes that help build molecules –Carbohydrates –Lipids

31 transport vesicles vesicles carrying proteins Golgi Apparatus Function –finishes, sorts, labels & ships proteins like UPS headquarters –shipping & receiving department –ships proteins in vesicles “UPS trucks” Structure –membrane sacs


33 Lysosomes Found only in animal cells Contain digestive enzymes Functions –Aid in cell renewal –Break down old cell parts –Digests invaders

34 Vacuoles Membrane bound storage sacs More common in plants than animals Contents –Water –Food –wastes

35 Mitochondria Have their own DNA Bound by double membrane Has inner foldings (Cristae) that increase the internal surface area

36 Mitochondria Break down fuel molecules ( cellular respiration) –Glucose –Fatty acids Release energy –ATP

37 Mitochondria Function –make ATP energy from cellular respiration sugar + O 2  ATP fuels the work of life in both animal & plant cells ATP

38 Plants make energy two ways! Mitochondria –make energy from sugar + O 2 cellular respiration sugar + O 2  ATP Chloroplasts –make energy + sugar from sunlight photosynthesis sunlight + CO 2  ATP & sugar –ATP = active energy –sugar = stored energy »build leaves & roots & fruit out of the sugars ATP sugar ATP

39 Chloroplasts Solar energy capturing organelle

40 Photosynthesis Takes place in the chloroplast Makes cellular food – glucose

41 Mitochondria are in both cells!! animal cells plant cells mitochondria chloroplast

42 Cells need workers = proteins! Making proteins –to run daily life & growth, the cell must… read genes (DNA) build proteins –structural proteins (muscle fibers, hair, skin, claws) –enzymes (speed up chemical reactions) –signals (hormones) & receptors –organelles that do this work… nucleus ribosomes endoplasmic reticulum (ER) Golgi apparatus

43 DNA RNA ribosomes endoplasmic reticulum vesicle Golgi apparatus vesicle protein on its way! protein finished protein Making Proteins TO: nucleus

44 Cells need to make more cells! Making more cells –to replace, repair & grow, the cell must… copy their DNA make extra organelles divide the new DNA & new organelles between 2 new “daughter” cells –organelles that do this work… nucleus centrioles

45 Centrioles Function –help coordinate cell division only in animal cells Structure –one pair in each cell

46 Cell Summary Cells have 3 main jobs –make energy need food + O 2 cellular respiration & photosynthesis need to remove wastes –make proteins need instructions from DNA need to chain together amino acids & “finish” & “ship” the protein –make more cells need to copy DNA & divide it up to daughter cells Our organelles do all those jobs!

47 Plasma Membrane Contains cell contents Double layer of phospholipids & proteins

48 Phospholipids Polar –Hydrophylic head –Hydrophobic tail Interacts with water

49 Movement Across the Plasma Membrane A few molecules move freely –Water, Carbon dioxide, Ammonia, Oxygen Carrier proteins transport some molecules –Proteins embedded in lipid bilayer –Fluid mosaic model – describes fluid nature of a lipid bilayer with proteins


51 Molecule Movement & Cells Passive Transport Active Transport Endocytosis ( phagocytosis & pinocytosis) Exocytosis

52 Passive Transport No energy required Move due to gradient –differences in concentration, pressure, charge Move to equalize gradient –High moves toward low

53 Types of Passive Transport 1. Diffusion 2. Osmosis 3. Facilitated diffusion

54 Diffusion Molecules move to equalize concentration

55 Osmosis Special form of diffusion Fluid flows from lower solute concentration Often involves movement of water –Into cell –Out of cell

56 Solution Differences & Cells solvent + solute = solution Hypotonic –Solutes in cell more than outside –Outside solvent will flow into cell Isotonic –Solutes equal inside & out of cell Hypertonic –Solutes greater outside cell –Fluid will flow out of cell


58 Facilitated Diffusion Differentially permeable membrane Channels (are specific) help molecule or ions enter or leave the cell Channels usually are transport proteins (aquaporins facilitate the movement of water) No energy is used

59 Process of Facilitated Transport Protein binds with molecule Shape of protein changes Molecule moves across membrane

60 Active Transport Molecular movement Requires energy (against gradient) Example is sodium-potassium pump

61 Endocytosis Movement of large material –Particles –Organisms –Large molecules Movement is into cells Types of endocytosis – bulk-phase (nonspecific) – receptor-mediated (specific)

62 Process of Endocytosis Plasma membrane surrounds material Edges of membrane meet Membranes fuse to form vesicle

63 Forms of Endocytosis Phagocytosis – cell eating Pinocytosis – cell drinking

64 Exocytosis Reverse of endocytosis Cell discharges material

65 Exocytosis Vesicle moves to cell surface Membrane of vesicle fuses Materials expelled

66 Membrane Proteins 1. Channels or transporters –Move molecules in one direction 2. Receptors –Recognize certain chemicals

67 Membrane Proteins 3. Glycoproteins –Identify cell type 4. Enzymes –Catalyze production of substances

68 Review of Eukaryotic Cells



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