Cell Boundaries and transport Ch. 7 Biology Cell Boundaries and transport

Copyright Pearson Prentice Hall Cell Boundaries All cells are surrounded by a thin, flexible barrier known as the cell membrane. Many cells also produce a strong supporting layer around the membrane known as a cell wall. Copyright Pearson Prentice Hall

Cell Membranes are Selectively Permeable The cell membrane regulates what enters and leaves the cell and also provides protection and support. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cell Membrane The lipid bilayer gives cell membranes a flexible structure that forms a barrier between the cell and its surroundings. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cell Membrane The composition of nearly all cell membranes is a double-layered sheet called a phospholipid bilayer. The cell membrane regulates what enters and leaves the cell. http://www.bioteach.ubc.ca/Bio-industry/Inex/graphics/lipidbilayer.gif Copyright Pearson Prentice Hall

Fluid-Mosaic Model Membrane composed of different molecules Phospholipids Cholesterol Proteins Phospholipid molecules form a flexible bilayer Cholesterol and protein molecules are embedded in it Carbohydrates act as cell identification tags Molecules move laterally

Fluid Mosaic Model Copyright © 2001 Pearson Education, Inc. publishing Benjamin Cummings

Selectively Permeable Because of polar and nonpolar regions of the phospholipid bilayer, the membrane allows certain materials in and certain materials out of the cell Permits exchange of nutrients, waste products, oxygen, and inorganic ions. Allows some substances to cross more easily than others: Hydrophobic molecules—hydrocarbons, CO2, and O2 dissolve in and cross membrane Very small polar molecules, including H2O can cross easily

Cell Walls The main function of the cell wall is to provide support and protection for the cell. Cell walls are found in plants, algae, fungi, and many prokaryotes. The cell wall lies outside the cell membrane. Most cell walls are porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily.

Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. The cell membrane regulates movement of dissolved molecules from the liquid on one side of the membrane to the liquid on the other side. Copyright Pearson Prentice Hall

Diffusion of Liquids The Plasma Membrane 4/23/2017 G. Podgorski, Biol. 1010

Passive Transport A substance will diffuse from where it is more concentrated to where it is less concentrated Only small, uncharged particles diffuse without assistance (H2O, CO2, and O2) http://sussexhigh.nbed.nb.ca/swift/biology11/Cell%20Boundaries%20ONLINE.ppt#276,25,Section G

Diffusion Through Cell Boundaries Particles in a solution tend to move from an area where they are more concentrated to an area where they are less concentrated. This process is called diffusion. When the concentration of the solute is the same throughout a system, the system has reached equilibrium. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries There is a higher concentration of solute on one side of the membrane as compared to the other side of the membrane. Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Solute particles move from the side of the membrane with a higher concentration of solute to the side of the membrane with a lower concentration of solute. The solute particles will continue to diffuse across the membrane until equilibrium is reached. Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries When equilibrium is reached, solute particles continue to diffuse across the membrane in both directions. Diffusion depends upon random particle movements. Therefore, substances diffuse across membranes without requiring the cell to use energy. Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Osmosis Osmosis Osmosis is the diffusion of water through a selectively permeable membrane. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Osmosis Water tends to diffuse from a highly concentrated region to a less concentrated region. If you compare two solutions, the more concentrated solution is hypertonic. The more dilute solution is hypotonic. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Osmosis When concentrations of solutions are the same on both sides of a membrane, the solutions are isotonic. http://www.uic.edu/classes/bios/bios100/summer2003/isotonic.jpg Copyright Pearson Prentice Hall

What kind of solution is inside the cell? Isotonic Outside the cell? Which direction will water move? In and out at the same rate

What kind of solution is inside the cell? Hypertonic Outside the cell? Hypotonic Which direction will water move? Into the cell

What kind of solution is inside the cell? Hypotonic Outside the cell? Hypertonic Which direction will water move? Out of the cell

Copyright Pearson Prentice Hall Osmosis Osmotic Pressure  Osmosis exerts a pressure known as osmotic pressure on the hypertonic side of a selectively permeable membrane. Because the cell is filled with salts, sugars, proteins, and other molecules, it will almost always be hypertonic to fresh water. If so, the osmotic pressure should produce a net movement of water into the cell. As a result, the volume of the cell will increase until the cell becomes swollen or bursts. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Osmoregulation Water balance between cells and their surroundings is crucial to organisms The control of water balance is osmoregulation Cells in large organisms are not in danger of bursting because they are bathed in fluids, such as blood, that are isotonic. Other cells are surrounded by tough cell walls that prevent the cells from expanding even under tremendous osmotic pressure. Copyright Pearson Prentice Hall

Osmosis Animal cell Plant cell Plasmolysis Flaccid Turgid http://ilovebacteria.com/Images/blood.jpg Animal cell Plant cell Plasmolysis Flaccid Turgid http://kvhs.nbed.nb.ca/gallant/biology/water_balance.jpg

Facilitated Diffusion The movement of specific molecules across cell membranes through protein channels is known as facilitated diffusion. Hundreds of different protein channels have been found that allow particular substances to cross different membranes. http://www.dwm.ks.edu.tw/bio/activelearner/05/images/ch05c3.gif Copyright Pearson Prentice Hall

Facilitated Diffusion Although facilitated diffusion is fast and specific, it is still diffusion. Therefore, facilitated diffusion will only occur if there is a higher concentration of the particular molecules on one side of a cell membrane as compared to the other side. No energy is used. Solute molecule Transport protein http://sussexhigh.nbed.nb.ca/swift/biology11/Cell%20Boundaries%20ONLINE.ppt#276,25,Section G Copyright Pearson Prentice Hall

Facilitated Diffusion The Plasma Membrane 4/23/2017 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins. https://mattwells.wikispaces.com/file/view/PLASMA~1.PPT G. Podgorski, Biol. 1010

Facilitated Diffusion The Plasma Membrane 4/23/2017 Facilitated Diffusion Some carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side. https://mattwells.wikispaces.com/file/view/PLASMA~1.PPT https://mattwells.wikispaces.com/file/view/PLASMA~1.PPT G. Podgorski, Biol. 1010

Active Transport Substances are transported across a membrane, against the concentration gradient Use carrier proteins embedded in the membrane Use energy (ATP) http://student.ccbcmd.edu/~gkaiser/biotutorials/eustruct/images/sppump.gif

Active transport in two solutes across a membrane FLUID OUTSIDE CELL Phosphorylated transport protein Active transport in two solutes across a membrane Transport protein First solute 1 First solute, inside cell, binds to protein 2 ATP transfers phosphate to protein 3 Protein releases solute outside cell Second solute 4 Second solute binds to protein 5 Phosphate detaches from protein 6 Protein releases second solute into cell Figure 5.18 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Active Transport: Sodium Potassium Pump

Sodium-Potassium Pump 3 Na+ ions inside the cell bind to the pump. ATP donates a phosphate to the pump The pump changes shape, transporting 3 Na+ across the membrane, and are released outside of the cell 2 K+ ions outside the cell bind to the pump The phosphate group is released and 2 K+ ions are transported across the membrane 2 K+ are released inside the cell http://gotoknow.org/file/somluckv/Cell_membrane06.jpg

Copyright Pearson Prentice Hall Active Transport Endocytosis and Exocytosis  Large molecules and even solid clumps of material may undergo active transport by means of the cell membrane. Endocytosis is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane. The pocket breaks loose from the outer portion of the cell membrane and forms a vacuole within the cytoplasm. Copyright Pearson Prentice Hall

Endocytosis Phagocytosis —endocytosis of solid particles Forms food vacuoles that fuse with lysosome to be digested Pinocytosis —endocytosis of fluid droplets Takes in solutes dissolved in the droplet http://student.ccbcmd.edu/~gkaiser/biotutorials/eustruct/images/phagocyt.gif http://student.ccbcmd.edu/~gkaiser/biotutorials/eustruct/images/pinocyt.gif

Active Transport Exocytosis Many cells also release large amounts of material from the cell, in a process called exocytosis. During exocytosis, the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell. http://www.stanford.edu/group/Urchin/GIFS/exocyt.gif

Material bound to receptor proteins Three kinds of endocytosis Pseudopod of amoeba Food being ingested Plasma membrane Material bound to receptor proteins PIT Cytoplasm Figure 5.19C

Used by cells to incorporate extracellular substances Exocytosis Endocytosis Process of exporting macromolecules from a cell by fusion of vesicles with the cell membrane Process of importing macromolecules into a cell by forming vesicles derived from the cell membrane Vesicle usually budded from the ER or Golgi and migrates to cell membrane Vesicle forms from a localized region of cell membrane that sinks inward; pinches off into cytoplasm Used by secretory cells to export products (insulin in pancreas; neurotransmitter from neuron) Used by cells to incorporate extracellular substances Figure 5.19B Figure 5.19A Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Receptor-mediated Endocytosis Imports specific macromolecules into the cell by inward budding of vesicles formed from coated pits Occurs in response to binding specific ligands to receptors on cell’s surface Harmful levels of cholesterol can accumulate in the blood if membranes lack cholesterol receptors Figure 5.19

Cell Boundaries and Transport Quiz Wiz

Copyright Pearson Prentice Hall Unlike a cell wall, a cell membrane is composed of a lipid bilayer. provides rigid support for the surrounding cell. allows most small molecules and ions to pass through easily. is found only in plants, fungi, algae, and many prokaryotes. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall If a substance is more highly concentrated outside the cell than inside the cell and the substance can move through the cell membrane, the substance will move by diffusion from inside the cell to outside. remain in high concentration outside the cell. move by diffusion from outside to inside the cell. cause water to enter the cell by osmosis. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The movement of materials in a cell against a concentration difference is called facilitated diffusion. active transport. osmosis. diffusion. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The process by which molecules diffuse across a membrane through protein channels is called active transport. endocytosis. facilitated diffusion. osmosis. Copyright Pearson Prentice Hall

The Diversity of Cellular Life The differences among living things arise from the ways in which cells are specialized to perform certain tasks and the ways in which cells associate with one another to form multicellular organisms. Copyright Pearson Prentice Hall

Unicellular Organisms Unicellular organisms are made up of only one cell. Unicellular organisms dominate life on Earth. Paramecium http://www1.broward.edu/~ssimpson/imgev5.jpg Euglena http://media-2.web.britannica.com/eb-media/15/12015-004-F85E856C.jpg Lactobacillus acidophilis http://bioinfo.bact.wisc.edu/themicrobialworld/Lactobacillus.jpg

Multicellular Organisms Organisms that are made up of many cells are called multicellular. There is a great variety among multicellular organisms. http://api.ning.com/files/ORxcmZcFiP6I7PYb0qOoWVxTv5ycZwBGGYXUO8Q5Vt4Jt2C1cvgUvrvIFwf4erW0i31kd7vYS-0skTwphV6eIL6-9sBS254X/Animal_diversity_October_2007.jpg

Multicellular Organisms Cells throughout an organism can develop in different ways to perform different tasks. This process is called cell specialization. http://219.221.200.61/ywwy/zbsw(E)/pic/ech12-2.jpg Copyright Pearson Prentice Hall

Animal cells are specialized in many ways. Red blood cells transport oxygen. Cells in the pancreas produce proteins.

Animal cells are specialized in many ways. Muscle cells allow movement. Nerve cells coordinate functions throughout the body.

Multicellular Organisms Specialized Plant Cells Plants exchange carbon dioxide, oxygen, water vapor, and other gases through tiny openings called stomata on the undersides of leaves. Highly specialized cells, known as guard cells, regulate this exchange. Stomata enclosed by guard cells. Copyright Pearson Prentice Hall

Levels of Organization The levels of organization in a multicellular organism are: individual cells tissues organs organ systems http://www.learner.org/courses/essential/life/images/show1.levels.jpg Copyright Pearson Prentice Hall

Levels of Organization In multicellular organisms, cells are the first level of organization. Copyright Pearson Prentice Hall

Levels of Organization Tissues Similar cells are grouped into units called tissues. A tissue is a group of similar cells that perform a particular function. Copyright Pearson Prentice Hall

Levels of Organization Most animals have four main types of tissue: muscle epithelial nervous connective Copyright Pearson Prentice Hall

Levels of Organization Organs  Organs are groups of tissues that work together to perform a specific function. Copyright Pearson Prentice Hall

Levels of Organization Organ Systems   In most cases, an organ completes a series of specialized tasks. A group of organs that work together to perform a specific function is called an organ system. Copyright Pearson Prentice Hall

Cell Diversity Quiz Wiz

Copyright Pearson Prentice Hall Cell specialization is characteristic of bacteria. all unicellular organisms. yeasts. multicellular organisms. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Which of the following cells is specialized for contraction? muscle cell red blood cell pancreatic cell nerve cell Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The stomach is an example of a(an) tissue. organ. organ system. organism. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Which of the following shows the levels of organization in an organism from the simplest to the most complex? organ system, organ, cell, tissue tissue, cell, organ, organ system cell, tissue, organ, organ system cell, organ, tissue, organ system Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Which of the following would probably contain the greatest variety of specialized cells? an organ system a tissue an organ a multicellular organism Copyright Pearson Prentice Hall

Acknowledgements Biology, by Miller and Levine. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without Essential Biology with Physiology, 2nd ed., by Campbell, Reece, and Simon, ©2007. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher. BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece, Mitchell, and Taylor, ©2003. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher. BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece, Mitchell, and Taylor, ©2001. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher.