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Transcript
Chapter 7 CELLS Chapter 7- Cell Structure and Function I. The Cell Theory A. Development of Cell Theory (history) 1. 1500’s- first lenses used by merchants to determine quality of cloth (look at precision of the weave) 2. 1600’s- microscope and telescope constructed a. Anton van Leeuuwenhoekmade simple compound microscope- observed living things in pond water for the first time b. Robert Hooke- looked at thin slice of cork. Noticed it was made of tiny chambers- called them “cells” First to ID cells. Hooke’s work stimulated others to search for cells in other living things. It became apparent that cells were basic units of all living things c. 1838- Matthias Schleiden- German botanist concluded all plants made of cells d. 1839– Theodor SchwannConcluded that all animals made up of cells c. 1855- Rudolf VirchowRussian physician said “Where a cell exists, there must have been a preexisting cell……..” What theory did this help to support? The Theory of Biogenisis B. The Cell Theory-summary of before mentioned scientists and other biologists is one of fundamental concepts of biology 1. All living things are composed of cells 2. Cells are the basic units of structure and function in all living things. 3. New cells are produced from existing cells II. Basic Cell Structures A. Cells come in many shapes and sizes a. Smallest- 0.2 micrometers (bacteria) b. Largest- birds egg and giant amoeba (1000 micrometers) B. Structures common in most Cells 1. Cell membrane-thin, flexible barrier around the cell. a. Many also have cell wall- strong layer around the cell membrane (found in plants, algae, fungi, and bacteria) b. Support and protect cells, while allowing them to interact with surroundings. 2. Nucleus-large structure containing cell’s genetic material- controls cell’s activities (“brain”) 3. Cytoplasm- “soup-like liquid” inside the cell membrane but not including nucleus. C. Prokaryotes and Eukaryotes- Scientists divide cells Into two groups depending on whether they have a nucleus or not. 1. Prokaryotes-no nucleus - ex. bacteria a. Smaller and simpler than cells of eukaryotes b. Do have cytoplasm and cell membrane c. Still carry out all activities associated with life 2. Eukaryotes-do contain nucleus and membrane bound organelles (includes plants, animals, fungi) a. Contain cytoplasm and cell membrane b. Also contain dozens of other specialized structures called organelles (means tiny organs) III. Cell Structure (a closer look) A. Cell Membrane 1. Regulates what enters and exits the cell 2. Provides protection and support 3. Made of double-layered sheet called- lipid bilayer with scattered proteins Lipid molecules 4. Membrane is a “mosaic” of many different kinds of molecules (protein channels and pumps, carbohydrate “identification cards”) B. Cell Wall- found in plants, algae, fungi, nearly all prokaryotes. NOT animal cells 1. Lies outside the cell membrane- provides support and protection for the cell 2. Made from fibers of carbohydrate (like cellulose) and proteins C. Nucleus- (first identified by Robert Brown in 1831 1. Controls most of cells processes and contains hereditary information (DNA) (controls activities with instructions for making proteins) 2. Found in eukaryotic cells 3. Chromatin and Chromosomes-DNA material visible inside the nucleus a. Chromatin- short condensed strands of DNA wrapped around histone proteins b. Chromosomes- chromatin condenses when cell gets ready to divide. Contains genetic material passed from one generation to the next c. Nucleolus- small dense region in nucleus where ribosomes are made d. Nuclear envelope- double membrane layer surrounding the nucleus containing tiny nuclear pores (allows materials to move into and out of nucleus. Eg. RNA) D. Cytoskeleton1. Network of protein filaments that help the cell to maintain its shape and involved in many forms of cell movement 2. Made up of microtubules and microfilaments a. Microtubules- serve as “tracks” along which organelles are moved. Important in cell division- help to separate chromosomes. Also form cillia and flagella which allow cells to move b. Microfilaments- long, thin fibers function in movement and support the cell E. Organelles in the Cytoplasm- (act like specialized “organs” in the cell) 1. Ribosomes- makes proteins (hormones and enzymes) on Rough Endoplasmic Reticulum.“Protein Synthesis” 2. Endoplasmic Reticulum- cell’s internal transport system. “Assembly line” a. Components of the cell membrane assembled, some proteins modified and stored like enzymes and hormones. b. Rough ER- (has ribosomes attached) and Smooth ER (no ribosomes) 3. Golgi Apparatus- “post office” of the cell. “mails out” the proteins made at ER. a. Carbohydrates and lipids (the packaging) enclose the proteins or hormones. b. Then sent to final destination 4. Lysosomes- “clean-up” crew of the cell a. Break down lipids, carbohydrates, proteins from food particles with enzymes (little “digestive sacs”) b. Break down ‘old’ cell parts, removing debris 5. Vacuoles- storage “sacs”- store water, salts, proteins, carbohydrates a. Large in plant cells (single large vacuole) b. In animals, smaller vacuoles called vesicles. They transport substances within the cell 6. Chloroplasts- found in plants and some other organisms (none found in animals and fungi) a. Produce energy-rich food (glucose) from sunlight by photosynthesis b. Green pigment- chlorophyll found in photosynthetic membranes 7. Mitochondria- found in nearly all eukaryotic cells “powerhouse” a. Use energy from food to power growth, development and movement b. Cells that require more energy- have more mitochondria D. Organelle DNA- DNA found in mitochondria and chloroplasts. Essential for normal function of both organelles. 1. Mitochondria and chloroplasts thought to be descendants of ancient prokaryotes. (theory of Lynn Margulis) 2. Thought to have formed relationship with early eukaryotic cells that benefited both cells 3. Mitochondrial DNA comes from mother IV. Movement Through the Membrane A. Cell Membrane- regulates what enters and exits the cell and provides support and protection 1. Lipid BilayerDouble layered sheet (not soluble in water) a. Contains protein molecules that form chemical “pumps” and channels to move material across membrane b. Carbohydrate molecules act like “ID cards” allowing cells to identify each other and to allow certain molecules in or out of the cell B. Diffusion- Movement of materials from areas of high concentration to areas of low concentration 1. All living cells have a liquid interior (cytoplasm) and are surrounded by liquid 2. Diffusion causes many substances to move across cell membrane but does not require the cell to use energy (called passive transport) 3. Equilibrium- when concentration of molecules are equal on both sides of membrane C. Osmosis- Diffusion of water molecules through selectively permeable membrane 1. Most membranes are selectively permeable (some materials can pass across membrane and others cannot) like “coffee filter” 2. Effects of osmosis- water rushes to dilute a. Isotonic- “same strength” b. Hypotonic- “below strength”water-in; greater solute concentration in cell. c. Hypertonic- “above strength”water-out; greater solute concentration out of cell. hypotonic solution hypertonic solution Isotonic solution Hypertonic-water rushes out of the cell to dilute the salt thus losing water in the cell making it “thirsty”. 3. Osmotic Pressure- osmosis exerts pressure on hypertonic side of a cell membrane a. Cells filled with salt, sugars, protiens and other molecules always hypertonic to fresh water. b. Osmotic pressure produces movement of water into a cell that is surrounded by fresh water 3. Osmotic Pressure- osmosis exerts pressure on hypertonic side of selectively permeable membrane a. Cells filled with salts, sugars, proteins and other molecules- always hypertonic to fresh water b. Osmotic pressure produces movement of water into cell that is surrounded by fresh water. c. Fortunately cells don’t come into contact with fresh water. Usually bathed in isotonic solutions (e.g. blood) or protected by cell wall (e.g. bacteria) or mechanism to pump out excess water (contractile vacuole) D. Facilitated Diffusion- membrane proteins help (faciliate) the movement of certain molecules across the cell membrane by diffusion (from high conc. To low conc.) that can’t diffuse through lipid bilayer directly.) 1. Many different protein channels for ions, sugars, salts. 2. Does not require addition of energy (passive transport) E. Active Transport- movement of molecules and ions against a concentration difference (from low to high) 1. Requires input of energy 2. Small molecules “pumped” across membrane (e.g. Na+ and K+ ions) 3. Large amounts of material transported through movements of the cell membrane a. Endocytosis- movement into cell by means of “infolding” 1). Pinocytosis- “cell drinking” 2). Phagocytosis- “cell eating” b. Exocytosis- removal of large amounts of material from a cell. Membrane of vacuole surrounding the material fuses with the cell membrane V. The Diversity of Life A. Unicellular Organisms- single celled organisms 1. Perform all life functions (grow, respond to environment, reproduce, etc.) 2. Unicellular organisms dominate life on Earth B. Multicellular Organisms 1. Cell specialization- cells in multicellular organisms are specialized to perform particular functions within the organism 2. Cells are interdependent and do not live on their own C. Levels of Organization- levels of organization that make it easier to classify and describe the cells within an organism 1. Cells- smallest unit of living thing (e.g. Nerve, muscle, bone, etc.) 2. Tissues- First level of organization in multicellular organism. group of similar cells that perform particular function 3. Organs- groups of tissues working together. (eg. Muscle, stomach, etc.) 4. Organ System- group of organs that work together (11 major organ systems in human body. E.g. Muscular, skeletal, circulatory, etc.) 5. Organism- living thing Video Quiz The cell theory applies to a. bacteria. b. plants and animals. c. multicellular organisms. d. all of the above The cell theory applies to a. bacteria. b. plants and animals. c. multicellular organisms. d. all of the above Who was the first person to identify and see cells? a. Anton van Leeuwenhoek b. Robert Hooke c. Matthias Schleiden d. Rudolf Virchow Who was the first person to identify and see cells? a. Anton van Leeuwenhoek b. Robert Hooke c. Matthias Schleiden d. Rudolf Virchow Which cell structure contains the cell's genetic material and controls the cell's activities? a. organelle b. nucleus c. cell envelope d. cytoplasm Which cell structure contains the cell's genetic material and controls the cell's activities? a. organelle b. nucleus c. cell envelope d. cytoplasm Prokaryotes lack a. cytoplasm. b. a cell membrane. c. a nucleus. d. genetic material. Prokaryotes lack a. cytoplasm. b. a cell membrane. c. a nucleus. d. genetic material. Eukaryotes usually contain a. a nucleus. b. specialized organelles. c. genetic material. d. all of the above. Eukaryotes usually contain a. a nucleus. b. specialized organelles. c. genetic material. d. all of the above. The main function of the cell wall is to a. support and protect the cell. b. store DNA. c. direct the activities of the cell. d. help the cell move. The main function of the cell wall is to a. support and protect the cell b. store DNA. c. direct the activities of the cell. d. help the cell move. Which of the following is a function of the cytoskeleton? a. helps a cell keep its shape b. contains DNA c. surrounds the cell d. helps make proteins Which of the following is a function of the cytoskeleton? a. helps a cell keep its shape b. contains DNA c. surrounds the cell d. helps make proteins Which organelle breaks down food into particles the cell can use? a. Golgi apparatus b. lysosome c. endoplasmic reticulum d. mitochondrion Which organelle breaks down food into particles the cell can use? a. Golgi apparatus b. lysosome c. endoplasmic reticulum d. mitochondrion Which organelle makes proteins using coded instructions that come from the nucleus? a. Golgi apparatus b. mitochondrion c. vacuole d. ribosome Which organelle makes proteins using coded instructions that come from the nucleus? a. Golgi apparatus b. mitochondrion c. vacuole d. ribosome Which organelle converts food into compounds that the cell uses for growth, development, and movement? a. chloroplast b. Golgi apparatus c. endoplasmic reticulum d. mitochondrion Which organelle converts food into compounds that the cell uses for growth, development, and movement? a. chloroplast b. Golgi apparatus c. mitochondria d. Endoplasimic reticulum The cell membrane contains channels and pumps that help move materials from one side to the other. What are these channels and pumps made of? a. carbohydrates b. lipids c. bilipids d. proteins The cell membrane contains channels and pumps that help move materials from one side to the other. What are these channels and pumps made of? a. carbohydrates b. lipids c. bilipids d. proteins Diffusion is the movement of molecules from a. an area of low concentration to an area of high concentration. b. an area of high concentration to an area of low concentration. c. an area of equilibrium to an area of high concentration. d. all of the above Diffusion is the movement of molecules from a. an area of low concentration to an area of high concentration. b. an area of high concentration to an area of low concentration. c. an area of equilibrium to an area of high concentration. d. all of the above Which means of particle transport requires input of energy from the cell? a. diffusion b. osmosis c. facilitated diffusion d. active transport Which means of particle transport requires input of energy from the cell? a. diffusion b. osmosis c. facilitated diffusion d. active transport The diffusion of water across a selectively permeable membrane is called a. osmotic pressure. b. osmosis. c. facilitated diffusion. d. active transport. The diffusion of water across a selectively permeable membrane is called a. osmotic pressure. b. osmosis. c. facilitated diffusion. d. active transport. An animal cell that is surrounded by fresh water will burst because the osmotic pressure causes a. water to move into the cell. b. water to move out of the cell. c. solutes to move into the cell. d. solutes to move out of the cell. An animal cell that is surrounded by fresh water will burst because the osmotic pressure causes a. water to move into the cell. b. water to move out of the cell. c. solutes to move into the cell. d. solutes to move out of the cell. Which term refers to cells having different jobs in an organism? a. multicellular b. cell specialization c. levels of organization d. unicellular Which term refers to cells having different jobs in an organism? a. multicellular b. cell specialization c. levels of organization d. unicellular A group of cells that perform similar functions is called a(an) a. organ. b. organ system. c. tissue. d. division of labor. A group of cells that perform similar functions is called a(an) a. organ. b. organ system. c. tissue. d. division of labor. What is the name of structure (a.)? Rough Endoplasmic reticulum What is the name of structure (b.)? ribosome Is this cell an animal or plant cell? Animal cell What is the name of structure (c.)? Cell membrane What is the name of structure (k.)? nucleolus What is the name of structure (g.)? Golgi bodies What is the name of structure (e.)? Smooth endoplasmic reticulum What is the name of structure (d.)? mitochondria What is the name of structure (m.)? vacuole What is the name of structure (k.)? Cell membrane What is the name of structure (j.)? Cell wall What is the name of structure (l.)? chloroplast What is the name of structure (f.)? nucleus What cell process is taking place below? phagocytosis What cell structures found in the organism below is responsible for removing excess water from the inside of the cell? Contractile vacuole What cell process is taking place below? osmosis