Cell Structure

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Cell Structure
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Parts of a microscope
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Scanning Electron Microscope
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Weevil
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Cat flea
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Deer tick
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Mosquito head
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Fly foot
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Diatom
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Diatom
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Cross section of a leaf
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Radiolarian
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Cell Theory

• All living organisms are composed of one or more
  cells.
• The cell is the most basic unit of life.
• All cells arise from pre-existing, living cells.

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• A. There are three basic structures of all types
  of cells
• 1. Cell membrane
• a. Contains a bilayer of lipids
• b. Is selectively permeable (allows
  only certain molecules through protein carriers)
• 2. Nucleus
• 3. Cytoplasm

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Plasma Membrane

• Separates intracellular fluids from extracellular
  fluids
• Allows certain substances in and out
• Glycocalyx is a glycoprotein are biological
  markers by which cells recognize one another

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Cell walls and membranes video
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Fluid Mosaic Model

• Double bilayer of lipids with imbedded, dispersed
  proteins
• Bilayer consists of phospholipids, cholesterol,
  and glycolipids
• Glycolipids are lipids with bound carbohydrate
• Phospholipids have hydrophobic and hydrophilic
  bipoles

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Functions of Membrane Proteins

• Functions of Membrane Proteins
• Transport
• Enzymatic activity
• Receptors for signal transduction

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Functions of Membrane Proteins

• Intercellular adhesion
• Cell-cell recognition
• Attachment to cytoskeleton and extracellular
  matrix

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Membrane Junctions

• Tight junction impermeable junction that
  encircles the cell
• Desmosome anchoring junction scattered along
  the sides of cells
• Gap junction a nexus that allows chemical
  substances to pass between cells

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Membrane Junctions Tight Junction impermeable
attachments
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• Examples of tight junctions occur in the urinary
  system. For example the bladder.

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Membrane Junctions Desmosomesmall space
between cells
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• Examples of Desmosomes occur in the skin.
  Although it mostly non-permeable, some substances
  can pass through.

• Ex Lotions, mercury

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Membrane Junctions Gap Junctionhave channels
between
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• Examples of gap junctions occur in the lymphatic
  system where the uptake of excess fluids need to
  pass quickly from one cell to the next.

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Diffusion movement of molecules with the
concentration gradient
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• http//people.eku.edu/ritchisong/301notes6.htm

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Facilitated Diffusion

• Movement of molecules with the help of proteins
  with a concentration gradient.

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Osmosismovement of water with a concentration
gradient
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Osmosis
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• Isotonic solutions with the same solute
  concentration as that of the cytosol
• Hypertonic solutions having greater solute
  concentration than that of the cytosol
• Hypotonic solutions having lesser solute
  concentration than that of the cytosol

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Sodium Potassium PumpMovement of sodium and
potassium in and out of a cell
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Active TransportMovement of molecules with the
help of protein against a concentration gradient
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• Transport of large particles and
  macromolecules across plasma membranes
• Exocytosis moves substance from the cell
  interior to the extracellular space
• Endocytosis enables large particles and
  macromolecules to enter the cell
• Phagocytosis pseudopods engulf solids and
  bring them into the cells interior(Eating
  particles)
• PinocytosisDrinking water

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Ex. Of Exocytosis
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Generation and Maintenance of Membrane Potential
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• B. Differences between animal and plant cells,
  plant cells have
• 1. Chloroplasts
• a. Contain pigments that absorb
  sunlight.
• 2. Vacuoles
• a. Large containers that store water.
• 3. Cell walls
• a. Rigid structure(contain cellulose)
  surrounding the cell.

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Cell Organelles
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1. Nucleus

• a. Boss of the cell. Its in charge of all
  things that occur in the cell.
• b. Contains the genetic material of
  an organismchromosomes.
• c. Surrounded by a nuclear envelope
  with pores (openings).
• d. Contains the nucleolus which makes
  ribosomes.

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• e. Cells or organisms with a nucleus
  (area that contains the DNA with a surrounding
  nuclear envelope) are called eukaryotic.
• f. Cells or organisms without a
  nucleus (DNA not contained within a nuclear
  envelope) are called prokaryotic.
• 1. Ex. bacteria

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Nuclear Envelope

• Selectively permeable double membrane barrier
  containing pores
• Outer membrane is continuous with the rough ER
  and is studded with ribosomes
• Pores regulate transport of large molecules into
  and out of the nucleus

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The Nucleus Video
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Nucleoli (nucleolus)

• Dark-staining spherical bodies within the nucleus
• Site of ribosome production
• Acts like the assistant to the boss

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Chromatin (protein withinchromosomes)

• Threadlike strands of DNA and histones
• Arranged in fundamental units called nucleosomes
• Form condensed, barlike bodies of chromosomes
  when the nucleus starts to divide

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Cell Cycle

• Interphase
• Growth (G1), synthesis (S), growth (G2)
• Mitotic phase
• Mitosis and cytokinesis
• Prophase, Metaphase, Anaphase, Telophase

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Interphase

• G1 (gap 1) metabolic activity and vigorous
  growth
• G0 cells that permanently cease dividing
• S (synthetic) DNA replication
• G2 (gap 2) preparation for division

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2. Cytoplasmcytosol

• a. The area between the nucleus and the cell
  membrane.
• b. Holds all the organelles in place.
• c. Gives shape to the cell.

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3. Centrioles

• a. Structures that aid in cell
  division.
• b. Found in the nucleus.

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Centrioles Video
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4. Mitochondria

• a. Known as the power house of
  the cell.
• b. Converts food into ATP to be
  used as energy.
• c. ATP Adenosine Triphosphate
• (Adenine plus three phosphate molecules.)

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5. Ribosomes

• a. Sites of protein synthesis
  (making).
• B. Responsible for making membranes needed by
• Cell.

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6. Endoplasmic ReticulumE.R.

• a. Passageway that transports materials
  throughout the cell.
• b. Rough E.R. is studded with
  ribosomes.
• c. Smooth E.R. is not studded
  with ribosomes. Also helps rid body of toxins.

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7. Golgi apparatus

• a. Passageway that modifies and packages
  proteins as they pass through.
• b. Stacked and flattened membranous sacs (stack
  of pancakes)
• c. Functions in modification, concentration, and
  packaging of proteins

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8. Lysosome

• a. Round organelle that rids the cell of
  unwanted waste.
• b. Digest ingested bacteria, viruses, and toxins
• c. Degrade nonfunctional organelles

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Lysosomes video
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9. Peroxisomes

• a. Detoxify harmful or toxic substances
• b. Neutralize dangerous free radicals

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10. Vacuole

• a. Containers that hold water and food for the
  cell.

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Vacuole video
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11. Cytoskeleton

• a. Contain microtubules and filaments to add
  structure to the cell.

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Cytoskeleton
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Microtubules

• Dynamic, hollow tubes made of the spherical
  protein tubulin
• Determine the overall shape of the cell and
  distribution of organelles

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Microfilaments

• Dynamic strands of the protein actin
• Attached to the cytoplasmic side of the plasma
  membrane
• Braces and strengthens the cell surface
• Attach to CAMs and function in endocytosis and
  exocytosis

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Intermediate Filaments

• Tough, insoluble protein fibers with high tensile
  strength
• Resist pulling forces on the cell and help form
  desmosomes

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Motor Molecules

• Protein complexes that function in motility
• Powered by ATP
• Attach to receptors on organelles

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Motor Molecules
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12. Cilia and flagella

• a. Hair-like projections that help move some
  types of cells.
• Cilia act like oars

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• Flagella act like a whip to move the cell

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Ciliary Action
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Processes

• Transcription- The making of a mRNA
• Translation- The making of protein