A View of the Cell: Cell Structure

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A View of the CellCell Structure
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Microscopy

• the use of microscopes to study cells
• Different types of microscopes
• Light microscope
• Transmission electron microscope
• Scanning electron microscope

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Compound light microscopes

• With light as its energy source, it uses a series
  of lenses to magnify up to 1500X

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Electron microscope

• Using a beam of electrons as its energy source,
  it can magnify structures up to 500,000 X their
  actual size

(a pin head)
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Transmission electron microscope

• TEM
• studies cellular interiors

Sample of TEM image
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Scanning electron microscope

• SEM
• studies cellular surfaces

Sample of SEM image
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The study of cellular structure and function is
called cytology, while the study of cells and
tissues in an organism is called histology.
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Levels of Organization

• Atom
• Molecule
• Organelles
• Cell
• Tissue
• Organs
• Systems
• Organisms

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The 10 Organ Systems
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Anton van Leeuwenhoek

• Mid-1600s
• Holland
• Used hand lens microscope to observe pond water
• Observed microscopic life, called them
  animicules

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Leeuwenhoek Microscope
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Robert Hooke
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Robert Hooke

• Mid-1600s
• England
• Used microscope to observe living tissues
• Named chambers cells

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Other Early Discoveries

• Dutrochet (early 1800s) first to suggest parts
  of all organisms are made of cells
• Brown in 1831 was the first to realize nearly
  ever cell contains a nucleus
• Dujardin (mid 1800s) used the term sarcode to
  describe protoplasm

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German cell biologists
1830s Matthias Schleidan concluded all plants
made from cells
1830s Theodor Schwann concluded that all
animals made from cells
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Rudolph Virchow

• 1855
• Germany
• New cells can only be produced from existing
  cells, confirmed by French scientist Louis Pasteur

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Cell Theory

• 1) All organisms are composed of one or more
  cells
• 2) The cell is the basic unit of structure and
  function of living things
• 3) All cells come from pre-existing cells

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To be a cell

• Plasma membrane (cell membrane) made of 2 layers
  of phospholipids
• -controls what enters and leaves cell
• -separates cell from its environment
• Cytoplasm carbohydrate and water based solution
  that suspends all internal parts of the cell
• -transports chemical substances in the cell
• - within the cell, but outside the nucleus

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To be a cell

• Ribosomes tiny round bodies that produce
  proteins
• DNA genetic material made of nucleic acids
• a) chromatin mass of fibers scattered
• through the nucleus (thread-like)
• b) chromosomes compact chromatin
• -direct store instructions for all
  cell
• functions
• -control inheritance of traits

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Two types of cells

• Prokaryote bacteria, archaebacteria
• Eukaryote protists, fungi, plants, animals

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Prokaryotic cell

• No nucleus
• No membrane bound organelles
• Small
• Simple
• Plasma membrane, ribosomes, cytoplasm, DNA

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Prokaryotic cell

• Capsule durable outer covering that some
  bacteria have for protection against water,
  acids, and viruses
• Flagella movement
• Cell wall protective layer around plasma
  membrane
• Pili anchoring and DNA exchange

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Eukaryote

• More complex
• 4 basic components organelles
• Organelles small structures that carry out
  specialized functions within a cell
• Many variations

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Plasma Membrane

• A flexible boundary between the cell and its
  environment maintains a balance of nutrients, etc
• Selective permeability
• A process in which a membrane allows some
  molecules to pass through while keeping others
  out

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Structure of the Plasma membrane

• Phospholipids
• A double layer that creates water-soluble
  outsides surrounding water insoluble insides
• TransporProteins
• Span the entire membrane to regulate which
  molecules enter and which leave

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Eukaryotic Cell Structures
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Nucleus ? cell control

• Chromatin
• Strands of genetic material (DNA) that contains
  the directions for making proteins. Forms
  chromosomes
• Nucleolus
• A prominent body within the nucleus, produces
  granules rich in RNA, each granule will become
  part of a ribosome
• Nuclear Envelope
• Surrounds the nucleus to keep chromatin and
  nucleolus in, while allowing RNA and proteins to
  exit

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Cytoplasmic Organelles

• Endoplasmic reticulum (Smooth and Rough)
• network of interconnected membranes (ER),
  storage, separation, and transport of substances
  made within the cell
• Smooth no ribosomes
• Rough dotted with ribosomes
• Ribosomes
• Free or bound to the ER, they carry out protein
  synthesis from amino acids

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Cytoplasmic Organelles

• Golgi apparatus
• A flattened stack of membranes that packages
  proteins into vesicles to be secreted by the cell
• Like a Post office or UPS.

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Cytoplasmic Organelles

• Vacuoles
• Membrane-bound compartments for temporary storage
  of materials
• May be very large in plant cells

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Cytoplasmic Organelles

• Lysosomes
• Small bodies filled with digestive enzymes that
  digest worn-out organelles, food particles, and
  even engulfed bacteria
• Responsible for the cells recycling of materials

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Cytoplasmic Organelles

• Chloroplasts
• Containing the green pigment, chlorophyll, these
  oval bodies capture light energy and turn it into
  chemical energy (photosynthesis)

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Cytoplasmic Organelles

• Mitochondria
• Rod-shaped organelle with many inner folds, which
  breaks down sugar to release its stored energy
  for cell use (cell respiration)
• Powerhouse of the cell

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Cytoplasmic Organelles

• Cytoskeleton
• Tiny rods and filaments (called microtubules and
  microfilaments) that form a supporting framework
  for the cell and function in cytoplasmic streaming

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Cytoplasmic Organelles

• Centrioles
• Pairs of clustered microtubules that play an
  important role in cell division

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Cytoplasmic Organelles

• Cilia Flagella
• External microtubules that aid the cell in
  locomotion or feeding

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Prokaryotic cell

• No nucleus
• No membrane bound organelles
• Small
• Simple
• Plasma membrane, ribosomes, cytoplasm, DNA

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Plant and Animal Cell Similarities

• Cell membrane that surrounds the cell
• Cytoplasm
• Nucleus that houses DNA
• Ribosomes for protein production
• Mitochondria that breaks down food and releases
  energy for the cell.
• Vacuoles for storage of food, water, and waste.
  Plants have one large vacuole and animals have
  many small vacuoles.
• Endoplasmic Reticulum (ER)
• Golgi bodies

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Differences in Plant and Animal Cells

• Plants contain a cell wall that surrounds the
  cell membrane and provides shape and support.
• Plants contain chloroplasts for photosynthesis
• Plant cells have a brick-like shape where as
  animal cells are more spherical.
• Plants use chloroplasts to store energy in
  glucose.
• Plants have one large vacuole animals have many
  small vacuoles.