CELLS

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CELLS

• CELLULAR COMPONENTS PROCESES

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MODERN CELL THEORY

1. The cell is the unit of structure and function in
   living things.
2. All cells arise from preexisting cells.
3. The cells of all living things carry on similar
   chemical activities.
4. All cells carry on their metabolic activities in
   organelles.

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There are two types of cells

• Prokaryotic- cells that DO NOT have a nucleus or
  other cell ORGANELLES
• Eukaryotic- cells with a NUCLEUS cell
  ORGANELLES
• Which is more complicated?
• REMEMBER YOU ARE EUKARYOTIC!

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• The parts of a cell that carry out a function are
  called cell ORGANELLES
• All cells have the following organelles
• Cell Membrane
• Cytoplasm
• Ribosomes
• Cytoskeleton

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Eukaryote cells ALSO have

• Nucleus
• Nucleolus
• Mitochondria
• Golgi Body Complex
• Endoplasmic Reticulum
• Vacuole
• Lysosome
• Centrioles (ANIMAL ONLY)
• Only Plant Cells have all of the above
• Cell Wall
• Chloroplast

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organelles

• little organs of the cell
• Organelles are present in BOTH plants and animals
  
• Carry out cellular functions!

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Nucleus

• cellular control center
• Controls cellular activity
• contains hereditary material (DNA in chromosomes)
  
• self duplicating structure -divides when the cell
  divides

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Nuclear membrane

• surrounds nucleus allowing certain materials to
  enter and leave

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Nucleolus

• round organelle in the nucleus
• usually a pair
• involved with the synthesis of RNA in the
  ribosomes

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Ribosomes

• sites of protein synthesis in the cytoplasm
• may be free in the cytoplasm or attached to the
  endoplasmic reticulum

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Endoplasmic reticulum (ER)

• cytoplasmic channels from the cell membrane to
  the nuclear membrane
• associated with the storage, synthesis, and
  transport of materials within the cell
• HIGHWAY for cell transport

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Cytoplasm (protoplasm)

• fluid like material between the cell membrane and
  the nucleus
• over 80 water
• HOLDS cell organelles in place
• site of most organelles and cellular chemical
  reactions

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Vacuole

• membrane bound cytoplasmic spaces containing
  materials
• Vacuoles are crucial in single-celled
  organisms
• Two Types
• Food vacuole--store and digest ingested food
• Contractile vacuole-pumps excess water from cells
  maintaining homeostasis

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Lysosome

• pouch containing digestive enzymes
• digest bacteria and some foods entering the cell
• Breaks down complex molecules into simpler
  molecules (SLICE)
• breakdown worn out cell organelles

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Mitochondrion

• "Powerhouse of the cell"
• carries on cellular respiration (contains
  respiratory enzymes that make ATP) (energy
  molecule)
• may contain DNA--is self duplicating-- divides
  when the cell divides
• found in greater s in active cells

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Golgi apparatus (complex)

• usually located near the nucleus
• synthesizes, packages, and secretes cellular
  products
• Packages waste harmful materials

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Plasma (cell) membrane

• The cell membrane is SEMI-PERMEABLE
• selectively regulates the flow of materials to
  and from the cell--thus maintaining chemical
  homeostasis within the cell
• The membrane acts like a BOUNCER only allowing
  certain things in and out of the cell It is made
  up of a lipid bilayer
• double layer of FAT - "Fat sandwich"
• transport through the plasma membrane likely
  occurs through these globular proteins (Fluid
  mosaic model)

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• Hydrophilic- attracts water
• Hydrophobic- repels water
• Why is it important that the cell membrane is
  made up of small phospholipids?

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ANIMAL CELL ORGANELLES ONLY

• Centriole- a cylindrical structure found in the
  cytoplasm which appears to function during the
  division of certain animal cells (usually near
  the nucleus)
• Helps animal cells divide

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PLANT CELL ORGANELLES ONLY

• Cell Wall- a nonliving structure which surrounds
  and supports the cell - composed mostly of
  cellulose
• Gives the plant cell structure support
• Chloroplasts- green in color-double membrane -
  contain the green pigment chlorophyll which
  carries on photosynthesis
• Uses the suns energy to make food for the plant

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photosynthesis

• the conversion of light energy to chemical energy
  by chlorophyll in chloroplasts
• Overall Net equation for photosynthesis
• 6 Water 6 Carbon dioxide yields glucose 6
  oxygen (when catalyzed by chlorophyll in the
  presence of sunlight)

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Levels of Tissue Organization

• cell - unit of structure of all life
• tissue - composed of groups of similar cells
• organs - composed of groups of tissues
  functioning together
• organ systems - composed of groups of organs
  functioning together

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Types of transport in Cells

• Passive transport - movement of substances
  through a membrane from a region of high to a
  region of low concentration - no energy needed
  (ATP) - diffusion and osmosis are examples of
  this
• Active transport - movement of substances through
  a membrane from a region of low concentration to
  a region of high concentration - requires
  cellular energy (ATP)

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• Whether passive or active transport is needed
  depends on the CONCENTRATION GRADIENT
• The concentration gradient is the difference in
  the concentration of a substance in two different
  spaces
• Concentration - the amount of a particular
  substance in a contained area compared with the
  amount of the same substance in another area
• Translation Amount of something in a space
  (water, salt, sugar, iron,)

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PROCESSES OF THE PLASMA MEMBRANE

• There are two types of passive transport
  Diffusion and Osmosis
• The goal of both diffusion and osmosis is to
  reach EQUILIBRIUM within the cell
• Equilibrium is a condition in which the movement
  in one direction is equal to the movement in
  another direction

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Diffusion

• the tendency of molecules to move from an area of
  higher concentration to an area of lower
  concentration
• (concentration gradient- diff in conc. between 2
  regions)

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Osmosis

• movement of water through a membrane from a
  region of higher to lower con.
• Solute - substance being dissolved in a liquid
  (ex. salt)
• Solvent - substance doing the dissolving (ex.
  water)
• Permeability - the extent to which a membrane
  will allow particular sized molecules to pass
• Semi-permeable membrane (selectively
  permeable)-allows some molecules to pass but not
  others

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• So, describe how Kool-Aid is made with regard
  to the terms solute and solvent. What is the
  universal solvent?

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• When comparing two solutions there are three
  possible relationships, We Identify the
  relationships by determining what would happen if
  a cell were placed in the solution.
• Hypertonic- A solution that causes a cell to
  shrink because of osmosis. Meaning water leaves
  the cell.
• Hypotonic- A solution that causes a cell to swell
  because of osmosis meaning water rushes into the
  cell.
• Isotonic-A solution that causes no change in cell
  size. Meaning there is no movement of water.

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If the fluid outside the cell has Then the outside fluid is Water moves Effect on the cell?
less water than is present inside the cell
more water than is present inside the cell
same amount of water as inside the cell
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• So, answer this question. Why do
  establishments offer free popcorn, peanuts, and
  pretzels to their patrons if they are serving
  beverages? What changes are taking place in the
  body to initiate the need for more beverages?

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Active Transport-

• the movement of a substance against the
  concentration gradient. (uphill)
• Active transport requires cell to USE ENERGY

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• Sodium pump - transports three sodium ions out of
  the cell and two potassium ions into the cell
• Both are against the concentration gradient
• The energy needed to perform this activity is
  supplied by ATP (adenosine tri-phosphate)
• ATP is a unit of energy made by the cell

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• Endocytosis- the movement of a substance into the
  cell by a vesicle. A vesicle is a form of
  packaging that is used by cells.
• Exocytosis- the movement of a substance out of
  the cell by a vesicle.
• Phagocytosis- cytoplasm of cell surrounds and
  engulfs particle--ex. ameba and white blood cell
• Pinocytosis- plasma membrane "pinches in" to
  permit entry of molecules too large to diffuse
  through