Cell Structure and Function

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Cell Structure and Function
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Learning Target

• I can discuss the history and components of the
  cell theory.

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Cells

• http//www.youtube.com/watch?vRU5Ymc00S4w

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Cells

• A cell is the smallest living unit of life
• Most are microscopic

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Discovery of Cells

• Robert Hooke from England (1665)
• Observed sliver of cork
• Saw row of empty boxes
• Coined the term cell because it reminded him of
  monks cells

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Discovery of Cells

• Anton van Leeuwenhoek
• From Holland
• Observed tiny moving organisms in pond water
• Animalcules

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Cell theory

• (1838)Theodor Schwann, German biologist
• (1839) Matthias Schleiden, German botanist
• all living things are made of cells
• (1855) Rudolf Virchow
• all cells come from
• pre-existing cells

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Principles of Cell Theory

• All living things are made of cells
• Cells are the basic units of structure and
  function in living things.
• New cells are produced from existing cells.

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Cell Size
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Cells Have Large Surface Area-to-Volume Ratio
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Characteristics of All Cells

• Cell (Plasma) membrane -- A surrounding
  protective membrane
• Cytoplasm cell contents in thick fluid
• Control center with DNA

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Learning Target

• I can discuss the history and components of the
  cell theory.

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Learning Target

• I can analyze the similarities and differences
  between prokaryotic and eukaryotic cells.

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Cell Types

• Prokaryotic
• Eukaryotic

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Review

• What are the characteristics of life?

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Prokaryotic Cells

• First cell type on earth
• Small with simple structure
• Possess all characteristics of life
• Cell type of Bacteria and Archaea

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Prokaryotic Cells

• No membrane bound nucleus
• Nucleoid region of genetic material (DNA)
• Organelles not bound by membranes

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Eukaryotic Cells

• Nucleus bound by membrane contains genetic
  material (DNA)
• Include fungi, protists, plant, and animal cells
• Possess many organelles

Protozoan
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Learning Target

• I can analyze the similarities and differences
  between prokaryotic and eukaryotic cells.

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Learning Target

• I can describe the functions of all major cell
  organelles.

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Composite Animal Cell
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Composite Plant Cell
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Cell Structure

• Eukaryotic cell is divided into two major parts
• Nucleus
• Cytoplasm
• the portion of the cell outside the nucleus
  organelles are suspended in this

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Nucleus

• Control center of the cell
• Found in plant and animal cells
• Surrounded by a double membrane
• Contains nearly all cells DNA
• Chromatin

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Nuclear Envelope

• Separates nucleus from rest of cell
• Double membrane
• Has nuclear pores
• to allow movement
• of materials into
• and out of the nucleus

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DNA

• Hereditary material stored in the nucleus
• Chromosomes contain the DNA which contain the
  instructions for controlling the cells functions
• Most of the time the DNA is coiled into chromatin
• Chromosomes are seen as coiled strands inside the
  nucleus is the genetic material seen in the
  nucleus

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Nucleolus

• Found inside the nucleus
• Most cells have 2 or more
• Directs synthesis of RNA
• Produces ribosomes

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Ribosomes

• Small particles of RNA and protein
• Located all over the cell
• Site of protein synthesis
• Assembles amino acids into proteins
• Can be free or attached

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Endoplasmic Reticulum

• Helps move substances within cells
• Network of interconnected membranes
• Two types
• Rough endoplasmic reticulum
• Smooth endoplasmic reticulum

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Rough Endoplasmic Reticulum

• Has ribosomes attached to surface
• Manufacture proteins
• Not all ribosomes are attached to rough ER. Some
  are free in the cytoplasm
• May chemically modify proteins from ribosomes

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Smooth Endoplasmic Reticulum

• No attached ribosomes
• Has enzymes that help build molecules
• Carbohydrates
• Lipids

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Golgi Apparatus

• Involved in synthesis of plant cell wall
• Modifies, sorts and packages proteins and other
  materials from the ER for storage in the cell or
  for secretion outside of the cell.

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Golgi Apparatus Function

• 1. Molecules come in vesicles
• 2. Vesicles fuse with Golgi membrane
• 3. Molecules may be modified by Golgi
• 4. Molecules pinched-off in separate vesicle
• 5. Vesicle leaves Golgi apparatus
• 6. Vesicles may combine with plasma membrane to
  secrete contents

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Lysosomes

• Contain digestive enzymes
• Functions
• Aid in cell renewal
• Use enzymes to break down
• food and worn out cell parts
• Digests invaders

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Vacuoles

• Membrane bound storage sacs
• More common in plants than animals
• Store
• Water
• Food
• Wastes

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Mitochondria

• Have their own DNA
• Bound by double membrane

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Mitochondria

• Produces the energy a cell needs to carry out its
  functions
• Break down fuel molecules (cellular respiration)
• Glucose
• Fatty acids
• Release energy
• ATP

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Chloroplasts

• Capture energy from the sun and convert it into
  chemical energy
• Photosynthesis

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Microfilaments/Microtubules

• Located all over the cell
• 3 functions
• mechanical support
• anchor organelles
• help move substances

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A actin, IF intermediate filament, MT
microtubule
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Cilia Flagella

• Provide motility
• Cilia
• Short
• Used to move substances outside human cells
• Flagella
• Whip-like extensions
• Found on sperm cells

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Cilia Flagella Structure

• Bundles of microtubules
• Continuous with plasma membrane

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Centrioles

• Pairs of microtubular structures
• Play a role in cell division

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Learning Target

• I can describe the functions of all major cell
  organelles.

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Learning Target

• I can explain how the cell membrane controls
  movement of substances both into and out of the
  cell and within the cell.

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Cell Membrane

• Also known as the plasma membrane
• Contains cell contents
• Double layer of phospholipids proteins
• Controls what enters or exits the cell

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Phospholipids

• Polar
• Hydrophilic head
• Hydrophobic tail
• Interacts with water

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Cell Walls

• Found in plants, fungi, many protists
• Surrounds plasma membrane provides support and
  protection for the cell

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Cell Wall Differences

• Plants mostly cellulose
• Fungi contain chitin

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Cytoplasm

• Viscous fluid containing organelles
• components of cytoplasm
• Interconnected filaments fibers
• Fluid cytosol
• Organelles (not nucleus)
• Storage substances

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Learning Target

• I can explain how the cell membrane controls
  movement of substances both into and out of the
  cell and within the cell.

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Learning Targets

• I can describe and contrast these types of cell
  transport osmosis, diffusion, facilitated
  diffusion and active transport.
• I can predict the effect of osmosis within cells
  based on the type of solution surrounding the
  cell.

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Movement Across the Plasma Membrane

• Materials move through the plasma membrane in two
  ways
• Passive transport
• Actively transport

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Passive Transport

• No energy required
• Move due to gradient
• differences in concentration, pressure, charge
• Move to equalize gradient
• Materials move from areas of high concentration
  to areas low concentration (downhill)

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Types of Passive Transport

• 1. Diffusion
• 2. Osmosis
• 3. Facilitated diffusion

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Diffusion

• Molecules move to equalize concentration

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Osmosis

• Special form of diffusion
• Fluid flows from lower solute concentration
• Often involves movement of water
• Into cell
• Out of cell

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Solution Differences Cells

• solvent solute solution
• Hypotonic
• Solutes in cell more than outside
• Outside solvent will flow into cell
• Cell will swell
• Isotonic
• Solutes equal inside out of cell
• Hypertonic
• Solutes greater outside cell
• Fluid will flow out of cell
• Cell will shrink

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Facilitated Diffusion

• Selectively permeable membrane
• Channels (are specific) help molecule or ions
  enter or leave the cell
• Channels usually are transport proteins
• (aquaporins facilitate the movement of water)
• No energy is required

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Process of Facilitated Transport

• Protein binds with molecule
• Shape of protein changes
• Molecule moves across membrane

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Membrane Proteins

• 1. Channels or transporters
• Move molecules in one direction
• 2. Receptors
• Recognize certain chemicals

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Membrane Proteins

• 3. Glycoproteins
• Identify cell type
• 4. Enzymes
• Catalyze production of substances

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Active Transport

• Molecular movement
• Requires energy (against gradient)
• Example is sodium-potassium pump

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Endocytosis

• Movement of large molecules
• Particles
• Organisms
• Movement is into cells
• Types of endocytosis
• bulk-phase (nonspecific)
• receptor-mediated (specific)

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Process of Endocytosis

• Plasma membrane surrounds material
• Edges of membrane meet
• Membranes fuse to form vesicle

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Forms of Endocytosis

• Phagocytosis cell eating
• Pinocytosis cell drinking

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Exocytosis

• Reverse of endocytosis
• Cell discharges material

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Process of Exocytosis

• Vesicle moves to cell surface
• Membrane of vesicle fuses
• Materials expelled

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End Chapter 5
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Learning Targets

• I can describe and contrast these types of cell
  transport osmosis, diffusion, facilitated
  diffusion and active transport.
• I can predict the effect of osmosis within cells
  based on the type of solution surrounding the
  cell.