Good Morning 1 1/13 Do Now : effects of acid sprayed tomato plants Take out notebook Discuss size of a cell and why they are the size that they are Volume to surface area ratio – activity 1

How Big is It? 2

3 The Plasma Membrane The Plasma Membrane - Gateway to the Cell Allows molecules to move in and out of the cell

What needs to get into and out of the cell? 4

CO 2 and Oxygen 5 Blood cells take Oxygen and nutrients to every cell in the body and CO 2 is removed

Wastes, Carbon dioxide and Urea pass out of cells through membrane 6

Cells are limited to size due to its Volume to Surface area Ratio 7

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9 Photograph of a Cell Membrane

10 Cell Membrane flexible The cell membrane is flexible and allows a unicellular organism to move

11 Homeostasis Balanced internal condition of cells Also called equilibrium Maintained by plasma membrane controlling what enters & leaves the cell

12 Functions of Plasma Membrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Provide anchoring sites for filaments of cytoskeleton

13 Structure of the Cell Membrane copyright cmassengale

14 Structure of the membrane is Made up of phospholipids, Proteins and cholesterol

15 FLUID- because individual phospholipids and proteins can move side-to-side within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above FLUID MOSAIC MODEL

16 hydrophilic Polar heads are hydrophilic “water loving ” hydrophobic Nonpolar tails are hydrophobic “water fearing” Cell Membrane Makes membrane “Selective” in what crosses

17 Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT phospholipid bilayer The cell membrane is made of 2 layers of phospholipids called the lipid bilayer

18 Small molecules and larger hydrophobic molecules move through easily. e.g. O 2, CO 2, H 2 O Semipermeable or selectively permeable Membrane

19 Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. Semipermeable Membrane BVR&pq=cell+membrane+animation&sc=8-23&sp=- 1&sk=#view=detail&mid=7FC1F9FD1D31B1EAB2057FC1F9FD1D31B1EAB205

20 Types of Transport Across Cell Membranes

21 Passive Transport Simple Diffusion  Doesn’t require energy  Moves high to low concentration Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out  Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.

22 Simple Diffusion NORequires NO energy HIGH to LOWMolecules move from area of HIGH to LOW concentration

23 DIFFUSION PASSIVE Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY

Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW) Solute= anything that is dissolved (in water)

25 Diffusion of Liquids

26 Passive Transport Facilitated diffusion  Doesn’t require energy  Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell.

27 Active Transport  Requires energy or ATP  Moves materials from LOW to HIGH concentration  AGAINST concentration gradient

28 Carrier Proteins Other carrier proteins change shape to move materials across the cell membraneOther carrier proteins change shape to move materials across the cell membrane

29 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating”

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31 Phagocytosis Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue) copyright cmassengale

32 Moving the “Big Stuff” Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. Exocytosis Exocytosis - moving things out. This is how many hormones are secreted

33 Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment

34 Three Forms of Transport Across the Membrane

35 Osmosis Diffusion of water across a membraneDiffusion of water across a membrane Moves from HIGH to LowMoves from HIGH to Low Diffusion across a membrane Semipermeable membrane

36 Diffusion of H 2 O Across A Membrane High H 2 O potential Low solute concentration Low H 2 O potential High solute concentration

37 Aquaporins Water Channels Protein pores used during OSMOSIS WATER MOLECULES copyright cmassengale

38 Cell in Isotonic Solution CELL 10% NaCL 90% H 2 O 10% NaCL 90% H 2 O What is the direction of water movement? The cell is at _______________. equilibrium ENVIRONMENT NO NET MOVEMENT

39 Cell in Hypotonic Solution CELL 10% NaCL 90% H 2 O 20% NaCL 80% H 2 O What is the direction of water movement?

40 Cell in Hypertonic Solution CELL 15% NaCL 85% H 2 O 5% NaCL 95% H 2 O What is the direction of water movement? ENVIRONMENT

Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution CYTOLYSIS- cell busts Hypertonic Solution PLASMOLYSIS - shriveling of cell

42 Cytolysis & Plasmolysis Cytolysis Plasmolysis

43 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic

44 hypotonichypertonic isotonic hypertonicisotonic hypotonic