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Cell Structure and Function

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Presentation on theme: "Cell Structure and Function"— Presentation transcript:

1 Cell Structure and Function

2 Cells Smallest living unit Most are microscopic

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

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

5 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)

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

7 The Work of Life What jobs do cells have to do for an organism to live… “breathe” gas exchange: O2 in vs. CO2 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

8 Cell Size

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

10 Cell Types Prokaryotic Eukaryotic

11 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

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

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

14 Bacterium Shapes

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

16 Representative Animal Cell

17 Representative Plant Cell

18 Organelles Cellular machinery

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

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

21 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

22 Cytoplasm Found in both plant and animal cells
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

23 Organelles Functional components within cytoplasm

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

25 DNA Hereditary material Chromosomes

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

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

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

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

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


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

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

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

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

36 Mitochondria ATP Function in both animal & plant cells
make ATP energy from cellular respiration sugar + O2  ATP fuels the work of life ATP in both animal & plant cells

37 Plants make energy two ways!
ATP Mitochondria make energy from sugar + O2 cellular respiration sugar + O2  ATP Chloroplasts make energy + sugar from sunlight photosynthesis sunlight + CO2  ATP & sugar ATP = active energy sugar = stored energy build leaves & roots & fruit out of the sugars sugar ATP

38 Chloroplasts Solar energy capturing organelle

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

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

41 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

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

43 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

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

45 Cell Summary Cells have 3 main jobs make energy make proteins
need food + O2 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!

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

47 Phospholipids Polar Interacts with water Hydrophylic head
Hydrophobic tail Interacts with water

48 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


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

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

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

53 Diffusion Molecules move to equalize concentration

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

55 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


57 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

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

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

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

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

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

63 Exocytosis Reverse of endocytosis Cell discharges material

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

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

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

67 Review of Eukaryotic Cells

68 Review of Eukaryotic Cells


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