Chapter 7: Cell Structure and Function

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Chapter 7 Cell Structure and Function
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Robert Hooke (1635-1703)

• English Scientist
• First to use the microscope to observe cells
• Coined the term cell
• Looked at cork cells

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Anton van Leeuwenhoek1632-1723

• Dutch scientist
• Invented the first compound microscope
• First to observe LIVING cells
• Blood cells and protists

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Robert Brown1773-1858

• Scottish botanist
• In 1831 he was the first person to observe the
  nucleus of a cell

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Schleiden Schwann1804-1881 1810-1882
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Developing Cell Theory 1838

• Schleiden
• Said all plants are made up of cells

• Schwann
• Said all animals are made up of cells

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Johannes RudolphPurkinje Virchow

• Coined the term protoplasm to refer to the
  jellylike material that fills the cell.

• Said all cells arise only from preexisting cells

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Cell Theory Overview

• All organisms are made of one or more cells.
• All cells carry on life activities.
• New cells arise only from other living cells.

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Prokaryotic vs Eukaryotic

• PROKARYOTIC
• Simplest form
• Lack membrane bound structures
• Example bacteria and some protists

• EUKARYOTIC
• Most common
• Possess membrane bound structures and a nucleus
• Found in most living things

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Sizes of Cells

• Eukaryotic are usually larger than prokaryotic
• Both nutrients and wastes are constantly entering
  and exiting cells
• Vary in size and shape

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Cell Structures and Organelles

• Organelles specialized internal structures of
  eukaryotic cells

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CELL WALL

• Found in most bacteria and all plant cells
• Gives cell its shape and provides protection
• Allows passage of materials
• In plant cells, it is made of cellulose
• http//www.cellsalive.com/

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THE NUCLEUS

• Control center or city hall of cell.
• Largest organelle
• Controls metabolism and cell reproduction

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Structure of nucleus

• Nuclear envelope membrane that surrounds the
  nucleus that acts in manner similar to the cell
  membrane
• Nucleolus dense are in center of nucleus where
  DNA,RNA, and proteins are found.
• site where ribosomes are produced

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Picture of nucleus
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MICROFILAMENTS

• Long, solid, threadlike structures
• Made of actin
• Involved in muscle contraction and cyclosis
• Movement of cytoplasm

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MICROTUBULES

• Hollow, cylindrical structures
• Helps to give cell its shape
• Made of tubulin
• Involved in mitosis
• More information

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Cytoplasm

• Watery material lying within the cell between the
  cell membrane and the nucleus
• Formally called the protoplasm by Purkinje
• Contains all the other organelles

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RIBOSOMES

• Very small
• mini factories of the cell
• Responsible for protein synthesis with the help
  of RNA
• Examples John Morrell, Gateway

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ENDOPLASMIC RETICULUM (ER)

• Fluid filled canals
• Continuous paths for transport of materials
• Divides the cell into compartments

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ER continued

• Acts as a street system in a city or conveyer
  at a factory
• Rough ER surface lined with ribosomes
• Smooth ER no ribosomes

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GOLGI BODIES

• Packaging, storage and processing of proteins
• Post Office of the cell
• Protein arrives from the ER to be packaged in
  vesicles.

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ER, Ribosome, Golgi
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LYSOSOMES

• Many strong digestive enzymes
• Produced by Golgi Bodies
• Involved in digestion of food in the cell
• Helps break down worn out organelles and wastes
• Garbage Truck
• Recycles cell materials

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VACUOLES

• Found mainly in plants but a few are found in
  animal cells
• Many different types
• Examples Food and contractile
• Act as a storage unit

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Contractile vacuoles

• Location in plant cells where excess water
  collects

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Chloroplasts

• A special type of chromoplast that contains
  chlorophyll
• Most important
• Contains grana and stroma
• Contain their own DNA
• Site of photosynthesis

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Chloroplast Structure
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MITOCHONDRIA

• Release energy used by the cell
• power plant
• Double membrane for extra surface area
• Responsible for cellular respiration
• Process by which energy is released using oxygen

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Mitochondria structure
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Mitochondria (powerhouse)

• Act similar to electric power plant
• Upto 300 to 800 per cell
• What advantage is their to having its own DNA?
• Can replicate itself

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Organelle DNA

• The only two organelles that contain their own
  DNA are mitochondria and chloroplasts
• In animals, all of an organisms organelle DNA is
  maternal in origin.
• Why?

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CELL MEMBRANE

• Controls what materials move in and out
• Helps to maintain homeostasis
• Similar to the city limits
• Made up of three substances
• Lipids, proteins, and carbohydrates

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Fluid-Mosaic Model
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Protein functions

1. Transport proteins control movement of
   materials.
2. Receptors act to signal cell when to begin or
   stop metabolizing.
3. Enzymes start chemical rxns.
4. Binding site for internal structures.

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Selectively permeable

• Some substances pass through while others may
  not.
• Regulates chemical composition
• Maintains homeostasis

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Diffusion

• Movement of molecules from a region of high
  concentration to a region of low concentration

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Osmosis

• Diffusion of WATER across a selectively permeable
  membrane from a region of high water
  concentration to a region of low water
  concentration.
• Osmotic pressure
• Increased pressure resulting from osmosis

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Isotonic solution

• Same concentration of dissolved substances in
  solution as there is in the cell
• Same water concentrations
• Net result
• No net gain or loss of water

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Hypotonic solution

• Lower concentration of dissolved substances in
  solution than in the cell
• More water outside the cell than inside the cell
• Net result

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Hypertonic pressure

• A high concentration of dissolved substances
  outside the cell
• More water in the cell than outside the cell
• Net result

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Facilitated diffusion vs Active transport

• Facilitated diffusion
• No energy needed
• Concentration gradient determines movement
• Uses protein channels

• ACTIVE
• Usually works against the conc. Gradient
• Often a transport protein helps the movement (ATP)

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Sodium-potassium pump
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Endocytosis

• Transport of material into the cell by means of a
  vesicle
• Pinocytosis small amounts of liquid engulfed
• Phagocytosis small amounts of solid ingested

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Exocytosis

• Transport of material out of the cell by means of
  a vesicle
• Exocytosis movie

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Cellular organization

• Simplest form of life unicellular Ex. bacteria,
  protists, algae
• Multicellular
• The simplest form is that of a colony
• Little if any cellular specialization
• Example Volvox (algae)

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Organization

• CELLS TISSUES
• ORGAN SYSTEM ORGANS
• ORGANISM

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Tissues

• A group of cells which are structurally similar
  and perform the same function.

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1. Epithelial Tissue

• Tissue that covers surfaces inside and outside
  the body
• Example skin
• Sheets of closely packed cells

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2. Connective Tissue

• Supports and binds tissues and organs together
• Widely separated cells
• EX. bone, blood

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3. Nervous Tissue

• Specialized for electrical impulse transport
• Ex. brain, spinal cords, nerves

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4. Muscle Tissue

• Specialized for contraction
• Lots of mitochondria

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Organs

• Group of tissues that work together to perform a
  specific function
• Ex. heart, stomach, flower

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Organ system

• Group of organs that perform a specific task
• Ex. digestive, skeletal, circulatory

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Assignment

• Pages 197-198
• 1-10,11,12,15,17,18,22,26,27
• Page 199 1-11