Cell structure and function

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Cell structure and function

• Show 2 video clips Honors book. Chapters 7.1- 7.2

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Voc Terms 7.1-7.2

• Cell
• Cell theory
• Cell membrane
• Nucleus
• Eukaryote
• Prokaryote
• Cytoplasm
• Organelle
• Vacuole
• Lysosome

• Cytoskeleton
• Centriole
• Ribosome
• Endoplasmic reticulum (smooth and Rough)
• Golgi apparatus
• Chloroplast
• Mitochondrion
• Cell wall
• Lipid bilayer
• Selectively permeable

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What to know

• Name the scientist who first observed living and
  non living cells.
• State the three principles of the cell theory.
• Explain why the cell is considered to be the
  basic unit of life.
• Know all cell organelles and functions
• Why are cells so small
• Explain a fluid mosaic model
• Know diff/sim between plant and animal and pro vs
  euk

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Discovery of cells

• Cell- is the smallest unit that can carry on all
  of the processes of life.
• 1665, English scientist Robert Hooke
• used a light microscope to look at cork
• Leeuwenhoek- Dutch trader (1632-1723)- first
  person to look at living cells (protists)

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Discovery of cells

• 150 years after Leeuwenhoek
• 1838- Matthias Schleiden plants were composed
  of cells
• Theodore Schwann- animal were also made of cells
• Rudolf Virchow (1821-1902) said all cells come
  from other cells

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Developments in Cell Biology

• 1665- Hooke discovers cork cells
• 1827- Baer discovers mammalian egg
• 1855- Virchow adds to cell theory
• 1857- Golgi discovers the Golgi apparatus in the
  cell
• 1996- Scotland researchers clone a sheep from an
  adult sheep cell
• 2004- Tissue engineering used to grow new skin an
  bone for transplant.

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Cell Theory

• 3 parts
• All living organisms are composed of one or more
  cells.
• Cells are the basic units of structure and
  function in an organism.
• Cells come only from the reproduction of existing
  cells.

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The Cellular Basis of Life

• All living things share several basic
  characteristics
• Organized parts- Made of cells
• Obtain energy from their surroundings/
• Perform chemical reactions (metabolism)
• 3. Change with time (Evolution)
• 4. Respond to their environments (Stimuli)
• 5. Reproduce (asexual and sexual)
• 6. Made of DNA
• 7. Regulate internal conditions (Homeostasis)
• 8. Grow and develop

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Cell Diversity

• Cells function influences
• its physical features!!
• Cell shape
• Cells shape can be simple or complex depending on
  the function of the cell
• Each cell has a shape that has evolved to allow
  the cell to perform its function effectively

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Cell Diversity

• Cell size
• Size of the cell is limited by the relationship
  of the cells outer surface area to its volume
• As the cell grows its volume increases
• Smaller the cell the more efficient it is in
  allowing nutrients and oxygen to pass in and out
  of the cells

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Basic Parts of the Cell

• 4 common features in all cells
• Plasma membrane or cell membrane, covers a
  cells surface and acts as a barrier between the
  inside and outside of a cell (in and out)
• Cytoplasm fluid, cytoskeleton, and organelles
  except cytoplasm
• - cytosol cytoplasm that has no membrane bound
  organelles (20 protein)
• 3. Coded information in the form of DNA
• -some float freely inside the cell or
• -Nucleus membrane bound organelle that contains
  a cells DNA
• 4. Ribosomes- makes proteins

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2 Basic types of cells

• Prokaryotes-
• a. lack a membrane bound nucleus and membrane
  bound organelles
• b. have DNA is concentrated in the Nucleoid
• c. have two domains Archaea and Bacteria
• 2. Eukaryotes-
• a. Organisms made up of one or more cells that
  have a nucleus and membrane-bound organelles
• b. have a variety of sub cellular structures
  called organelles
• c. tend to be much larger than
• prokaryotes

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Cellular Organization

• Cells are specialized and unable to survive
  independently
• Cells? Tissues? organs? Organ system
• Muscle cells? muscle tissues? Heart? circulatory
  system

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Cell organelles and features

• Plasma membrane
• - it allows for only certain molecules to enter
  or leave the cell
• - it separates internal metabolic reactions from
  the external environment
• -excretes waste
• - interaction with environment

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Membrane Lipids

• Made of phospholipids
• They have both a polar (hydrophilic) phosphate
  head and two non polar (hydrophobic) fatty acid
  tails
• Double layer is called phospholipid bilayer
• Eukaryotes also have lipids called sterols
  located between the tails of the phospholipids
  (most common is cholesterol, prevent the membrane
  from freezing at low temps)

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Membrane Proteins

• Integral proteins- specific proteins that are
  located in the lipid bilayer
• Peripheral proteins- located on the outside of
  the membrane not embedded in it
• Fluid mosaic model
• - phospholipid bilayer behaves like a fluid more
  than it behaves like a solid
• - Proteins can mover laterally within the bilayer

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Nucleus

• Houses and protects genetic information
• Chromatin- DNA, long thin fibers
• Chromosomes- condensed DNA
• Nuclear Envelope- double membrane that surrounds
  the nucleus
• Nuclear pores- protein-lined holes, passageways
  for RNA and other materials to enter or exit the
  nucleus
• Nucleolus- dense area, where DNA is concentrated
  and it is making ribosomal RNA
• Ribosomes- organelles made of protein and protein
  synthesis in the cytoplasm

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Mitochondria

• Tiny organelles that transfer energy from organic
  molecules to ATP
• Powers most of the cells chemical reactions
• Highly active cells-muscles cells have hundreds
  of them
• Fat storing cells have few
• Inner and outer phospholipid membrane
• Inner membrane has many folds- cristae, which
  contain proteins that carry out energy harvesting
  chemical reactions
• Contain own DNA
• Can reproduce only by the division of
• preexisting mitochondria
• Originated from prokaryotic cells-
• symbiotic relationship

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Ribosome

• Small, roughly spherical organelles that are
  responsible for protein synthesis
• Do not have a membrane
• Made of protein and RNA molecules
• Developed in the nucleolus and completed in the
  cytoplasm
• Some float freely in cytosol other in R-ER

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Endoplasmic Reticulum

• System of membranous tubes and sacs (cisternae)
• Intracellular highway- particles move from one
  part to another
• Amount depends on the cells activity
• Two types
• Rough
• Smooth

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Rough Endoplasmic Reticulum

• Interconnected, flattened sacs covered with
  ribosomes
• Produces phospholipids and proteins
• Proteins are exported from the cell- digestive
  enzymes
• Abundant in cells that produce large amounts of
  protein for export , digestive glands,
  antibody-producing cells

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Smooth ER

• Has no ribosomes
• Most cells have few S-ER
• Builds lipids- cholesterol
• Ovaries/testes- produce steroid hormone estrogen
  and testosterone
• Skeletal and heart muscles- release calcium
  stimulates contraction
• Abundant in liver and kidney- detoxify
  drugs/poisons

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Golgi Apparatus

• System, flattened membranous sacs
• Packaging system- UPS
• 1. receive vesicles from ER with new proteins or
  lipids
• 2. travel in the Golgi- modify them
• 3. redirected to various parts of the cell

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Vesicles

• Can be small, spherically shaped sacs that are
  surrounded by a single membrane
• Lysosomes- vesicles that bud from the Golgi and
  contain digestive enzymes
• Peroxisomes- abundant in liver and kidney (H2O2)
• Other-glyoxysomes, endosome, contractile vacuoles
• Protein synthesis

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Vesicles cont

• 4. Protein synthesis
• a. proteins are assembled by ribosomes on the
  rough ER
• b. Vesicles transport proteins to the golgi
  apparatus
• c. the golgi modifies protein and packages them
  in new vesicles
• d. vesicles release protein that have
  destinations outside the cell
• e. vesicles containing enzymes remain inside the
  cell as lysosomes, peroxisomes, endosomes

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Cytoskeleton

• Network of thin tubes and filaments that
  crisscrosses the cytosol, give it shape
• Microtubules- hollow tubes made of protein called
  tubulin, anchor, shape
• Microfilaments- long threads of the beadlike
  protein actin, double strands
• Intermediate filaments- rods that anchor the
  nucleus, shape of nucleus
• Cilia and flagella- hair like structures that
  extend from the surface of the cell
• Centrioles- occur in animal cells , organize for
  cell division

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Plant cells p 87

• Plants have 3 structures that are extremely
  important to plant function
• 1. cell walls
• 2. large central vacuoles
• 3.chloroplast
• Plants are different than animals- plant make
  their own carbon-containing molecules from the
  carbon in the environment (photosynthesis)

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Parts

• Cell wall- rigid layer that lies outside the
  plasma membrane, made of carbohydrates called
  cellulose
• Central vacuole- stores water, metabolic wastes,
  other materials, 90 of cell, if the cell shrinks
  the plant wilts
• Chloroplast- organelles that have own DNA, have a
  double membrane
• a. chloroplast- light energy to make carbs,
  (thylakoids, chlorophyll)
• b. chromoplast- colorful pigments

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Prokaryotes vs Eukaryotes
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Plant vs Animal
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What do all cells have?

• Common features
• 1.
• 2.
• 3.
• 4.

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Animations

• http//www.cellsalive.com/cells/cell_model.htm
• http//www.scsc.k12.in.us/SMS/Teachers/Martin/intr
  o.htmResources
• http//www.biology4kids.com/files/cell_main.html
• http//www.ibiblio.org/virtualcell/tour/cell/cell.
  htm
• http//projects.edtech.sandi.net/miramesa/Organell
  es/animal.html
• http//library.thinkquest.org/12413/structures.htm
  lcentrioles
• http//learn.genetics.utah.edu/content/begin/cells
  /insideacell/
• http//www.emc.maricopa.edu/faculty/farabee/biobk/
  BioBookCELL2.html