Cells: Agricultures Building Blocks Lesson 2 Structure

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CellsAgricultures Building BlocksLesson 2 -
Structure

• By Allen Rhoadarmer
• Mesa Public Schools

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Student Objectives

• Student will be able to
• Explain the variations in the different types of
  cells
• Describe the structures found in cells
• Analyze the functions of the various parts of
  cells
• Explain the process of diffusion

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Student Objectives

• Student will be able to
• Explain the process of osmosis
• Explain the concept of homeostasis

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Cell Comparison
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Cell Size and Shape

• The shapes of cells are quite varied with some,
  such as neurons,
• being longer than they are wide and others

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Cell Size and Shape

• Others such as parenchyma (a common type of plant
  cell)

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Cell Size and Shape

• and erythrocytes (red blood cells) being
  equidimensional

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Cell Size and Shape

• Some cells are encased in a rigid wall, which
  constrains their shape, while others have a
  flexible cell membrane (and no rigid cell wall).

Click for Virus Clip
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Cell Size and Shape

• The size of cells is also related to their
  functions.
• Eggs (or to use the Latin word, ova) are very
  large, often being the largest cells an organism
  produces.

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Sizes of viruses, cells, and organisms
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The Cell Wall

• Plant cells have a cell wall
• Animal cells do not have cell walls

Structure of a typical plant cell.
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The Cell Wall

• 3. The cell wall serves as the outermost barrier
  of the cell
• 4. The cell wall is located outside the plasma
  membrane.

Structure of a typical plant cell.
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The Cell Wall

• 5. The cell wall is composed of cellulose
• a. Provides rigidity for the walls of the cell
• b. Provides some support for the entire plant
• c. Is very important in the production of
  agricultural products such as lumber and paper

Structure of a typical plant cell.
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The Cell Wall

• Cellulose is a polysaccharide that is composed of
  unbranched chains of glucose

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The Cell Wall

• It is the major structural carbohydrate of
  plants, insoluble in water, and indigestible in
  the human intestine.

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The Cell Wall

• 6. Cell walls of softer plant parts
• A. Pectin aids in giving the cell wall strength
• B. The cell walls of softer plants have two
  layers
• While harder plant parts may have several layers

Lily Parenchyma Cell (cross-section)
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The Cell Wall
Click here for Cell Clip

• Structure of an animal cell -- No Cell Wall

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The Cell Wall

• Liver Cell
• Animal cells do not have cell walls

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The Cell Membrane

• The cell membrane functions as a semi-permeable
  barrier, allowing a very few molecules across it
  while fencing the majority of organically
  produced chemicals inside the cell.

Diagram representing the cell membrane.
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The Cell Membrane

• The most common molecule in the model is the
  phospholipid
• These phospholipids are aligned tail to tail

Diagram representing the cell membrane.
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The Cell Membrane

• Cholesterol is another important component of
  cell membranes embedded in the hydrophobic areas
  of the inner (tail-tail) region.

Diagram representing the cell membrane.
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The Cell Membrane

• Most bacterial cell membranes do not contain
  cholesterol

Diagram representing the cell membrane.
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The Cell Membrane

• Proteins are suspended in the inner layer,
  although the more hydrophilic areas of these
  proteins "stick out" into the cells interior and
  outside of the cell.

Diagram representing the cell membrane.
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The Cell Membrane

• These proteins function as gateways that will, in
  exchange for a price, allow certain molecules to
  cross into and out of the cell.

Diagram representing the cell membrane.
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The Cell Membrane

• These integral proteins are sometimes known as
  gateway proteins.

Diagram representing the cell membrane.
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The Cell Membrane

• The outer surface of the membrane will tend to be
  rich in glycolipids, which have their hydrophobic
  tails embedded in the hydrophobic region of the
  membrane and their heads exposed outside the
  cell.

Diagram representing the cell membrane.
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The Cell Membrane

• The outer surface of the membrane will tend to be
  rich in glycolipids, which have their hydrophobic
  tails embedded in the hydrophobic region of the
  membrane and their heads exposed outside the
  cell.

Diagram representing the cell membrane.
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The Cell Membrane

• Phospholipids are made up of a hydrophilic head
  and a hydrophobic tail

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The Cell Membrane
Cell Membranes from Opposing Neurons
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The Cell Membrane

• The contents (both (1) chemical and (2)
  organelles) of the cell are termed
• Protoplasm,

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The Cell Membrane

• They are further subdivided into
• Cytoplasm
• (all of the protoplasm except the contents of the
  nucleus) and
• Nucleoplasm
• (all of the material, plasma and DNA etc. within
  the nucleus).

Nucleus with Nuclear Pores
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The Cell Membrane

• Cell membranes - review
• 1. Found inside the cell wall
• 2. Found in plant and animal cells
• 3. All material that passes into and out of cell
  must go through the cell membrane
• 4. The cell membrane is selectively or semi
  permeable
• It only allows certain materials to pass through

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The Cell Membrane

• Cell membranes
• 5. The membrane allows materials needed for life
  processes to pass through and also gets rid of
  waste materials left over from these processes

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The Cell Membrane

• Cell membranes
• 6. Materials pass though the membrane in a
  process called diffusion
• Molecules in solution pass through the membrane
  from a region of higher concentration of
  molecules to a region of lower concentration of
  molecules

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The Cell Membrane

• Cell membranes
• 7. Water is passed through the cell membrane
  through osmosis

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The Cell Membrane

• Cell membranes
• 8. Through the process of diffusion and osmosis,
  the amount of materials moving in and out of
  cells and cell parts are regulated
• a. allows the cell to remain constant even though
  conditions in the environment might change

Click Here for Osmosis Clip
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The Cell Membrane

• Cell membranes
• 8. Through the process of diffusion and osmosis,
  the amount of materials moving in and out of
  cells and cell parts are regulated
• b. Homeostasis
• Ability of an organism to remain stable when
  conditions around it are changing

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The Cell Membrane

• Cell membranes
• 8. Through the process of diffusion and osmosis,
  the amount of materials moving in and out of
  cells and cell parts are regulated
• c. Turgid
• Cells filled with the proper amount of water are
  filled out and taut

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The Nucleus

• The nucleus occurs only in eukaryotic cells, and
  is the location of the majority of different
  types of nucleic acids

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The Nucleus

• Deoxyribonucleic acid
• DNA
• Is the physical carrier of inheritance and with
  the exception of plastid DNA
• all DNA is restricted to the nucleus.

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The Nucleus

• Ribonucleic acid
• RNA
• Is formed in the nucleus by coding off of the DNA
  bases.
• RNA moves out into the cytoplasm.

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The Nucleus

• The nucleolus is an area of the nucleus (usually
  2 nucleoli per nucleus) where ribosome's are
  constructed.

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The Nucleus

• Composition of the nucleus
• a. Nucleic acids
• b. Protein
• c. Enzymes
• d. Surrounded by a double-layer membrane

Structure of the nucleus. Note the chromatin,
uncoiled DNA that occupies the space within the
nuclear envelope.
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The Nucleus

• Liver cell nucleus and nucleolus
• Cytoplasm, mitochondria, endoplasmic reticulum,
  and ribosomes also shown.

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The Nucleus

• The nuclear envelope is a double-membrane
  structure. Numerous pores occur in the envelope,
  allowing RNA and other chemicals to pass, but the
  DNA not to pass.

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The Nucleus

• Structure of the nuclear envelope and nuclear
  pores.

Nucleus with Nuclear Pores
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Cytoplasm

• The cytoplasm is the material between the plasma
  membrane (cell membrane) and the nuclear envelope.

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Cytoplasm

• Fibrous proteins that occur in the cytoplasm
• Referred to as the cytoskeletin maintain the
  shape of the cell as well as anchoring
  organelles, moving the cell and controlling
  internal movement of structures.

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Cytoplasm

• Cytoskeleton  
• A three-dimensional network of microtubules and
  filaments that provides internal support for the
  cells, anchors internal cell structures, and
  functions in cell movement and division.

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Cytoplasm

• Microtubules function in cell division and serve
  as a "temporary scaffolding" for other
  organelles.

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Cytoplasm

• Actin filaments are thin threads that function in
  cell division and cell motility.

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Cytoplasm

• Intermediate filaments are between the size of
  the microtubules and the actin filaments.

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Cytoplasm

• 1. Cytoplasm
• a. Thick clear fluid that surrounds the nucleus
• b. Contains all of the material needed by the
  cell to conduct life processes
• c. Fluid in cytoplasm aids in moving essential
  materials
• d. Fluid in cytoplasm is constantly moving and
  suspends other parts of the cell

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Cytoplasm

• 2. In certain organisms, like amoebas, movement
  is obtained through the movement of cytoplasm
  within the cell

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Cytoplasm

• 3. In certain cells, pigments within the
  cytoplasm give an organism its color.

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Organelles

• Small structures within the cell that serve
  different roles
• They support the cell in much the same way that
  organs support the body of an animal

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Organelles - Mitochondria

• 1. Mitochondria
• a. Shaped like a peanut
• b. Function
• (1) To break down food nutrients
• (2) Supply the cell with energy

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Organelles - Mitochondria

• 1. Mitochondria have two membranes, an inner and
  an outer, clearly visible in this electron
  microscope photo of a mitochondrion.

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Organelles - Mitochondria

• 1. The inner membrane folds into a series of
  cristae, which are the surfaces on which ATP is
  generated.

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Organelles - Mitochondria

• 1. Mitochondria (singular mitochondrion) are the
  sites of aerobic respiration, and generally are
  the major energy production center in eukaryotes.
  

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Organelles - Mitochondria

• 1. Mitochondria contain their own DNA (termed
  mDNA)

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Organelles - Mitochondria

• 1. The mitochondrion has been termed the
  powerhouse of the cell.

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Organelles - Mitochondria

• 1. Muscle Cell Mitochondria

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Organelles - Vacuoles

• 2. Vacuoles
• a. Serve as a storage compartment for the cell
• b. Consist of membrane that encloses water and
  other material

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Organelles - Vacuoles

• 2. Vacuoles
• c. Store the nutrients and enzymes needed by the
  plant
• d. Provide a storage space for the waste
  materials given off by the cell

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Organelles - Microtubules

• 3. Microtubules
• a. Shaped like a small hollow tube
• b. composed of protein

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Organelles - Microtubules

• 3. Microtubules
• c. Act as the bones of the cell
• 1. Give support to the cell
• 2. Give cells their shape

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Organelles - Microtubules

• 3. Microtubules
• d. Assist in the movement of chromosomes during
  cell division

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Organelles Microfilaments

• 4. Microfilaments
• a. Fine fiber like structures composed of protein
• b. Help the cell to move by waving back and forth

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Organelles - Ribosomes

• 5. Ribosomes are the sites of protein synthesis.

• They are not membrane-bound and thus occur in
  both prokaryotes and eukaryotes.

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Organelles - Ribosomes

• 5. Ribosomes are slightly larger than prokaryotic
  ones.

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Organelles - Ribosomes

• Structurally the ribosome consists of a small and
  larger subunit.

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Organelles - Ribosomes

• Structurally the ribosome consists of a small and
  larger subunit.

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Organelles - Ribosomes

• Biochemically the ribosome consists of ribosomal
  RNA (rRNA) and some 50 structural proteins.

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Organelles - Ribosomes

• Often ribosomes cluster on the endoplasmic
  reticulum, in which case they resemble a series
  of factories adjoining a railroad line.

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Organelles - Ribosomes

• Rough (endoplasmic reticulum) ER is studded with
  ribosomes smooth ER is not

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Organelles - Ribosomes

• Ribosomes and Polyribosomes - liver cell

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Organelles Endoplasmic Reticulum

• 6. Endoplasmic reticulum
• a. Large webbing or network of double membranes
  that is positioned throughout the cell

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Organelles Endoplasmic Reticulum

• 6.Endoplasmic reticulum
• b. Provides the means for transporting material
  through the cell

The endoplasmic reticulum. Rough endoplasmic
reticulum is on the left, smooth endoplasmic
reticulum is on the right
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Organelles Endoplasmic Reticulum

• ER bound to ribosomes is called rough ER because
  the ribosomes appear as black dots on the ER in
  electron microscope photos, giving the ER a rough
  texture.

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Organelles Endoplasmic Reticulum

• Rough Endoplasmic Reticulum with Ribosomes

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Organelles Endoplasmic Reticulum

• Rough ER has ribosomes attached to it, and smooth
  ER does not.

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Organelles Golgi Apparatus

• 7. Golgi apparatus
• a. shaped like a group of flat sacs that are
  bundled together

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Organelles Golgi Apparatus

• 7. Golgi apparatus
• b. Function to remove water from the proteins and
  prepare them for export from the cell

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Organelles Golgi Apparatus

• 7. Structure of the Golgi apparatus and its
  functioning in vesicle-mediated transport.

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Organelles Golgi Apparatus

• 7. Structure of the Golgi apparatus and its
  functioning in vesicle-mediated transport.

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Organelles Golgi Apparatus

• 7. Golgi Apparatus in a plant parenchyma cell

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Organelles - Lysosomes

• 8. Lysosomes are relatively large vesicles formed
  by the Golgi.

Role of the Golgi in forming Lysosomes
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Organelles - Lysosomes

• 8. Lysosomes
• a. The digestive unit of the cell

Role of the Golgi in forming lysosomes
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Organelles - Lysosomes

• 8. Lysosomes
• b. They digest
• Proteins
• Carbohydrates
• Foreign materials
• Other molecules

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Organelles - Lysosomes

• 8. Lysosomes
• c. Worn out (nonfunctional) cell parts are broken
  down by lysosomes

Role of the Golgi in forming lysosomes
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Organelles Plastids

• 9. Plastids are also membrane-bound organelles
  that only occur in plants and photosynthetic
  eukaryotes.

Structure of the chloroplast
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Organelles Plastids

• 9. Plastids
• a. Found only in plant cells
• b. Three types
• 1. Chloroplasts
• 2. Leucoplasts
• 3. Chromoplasts

Structure of the chloroplast
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Organelles Plastids

• 9. Plastids
• Like mitochondria, (1)chloroplasts have their own
  DNA, termed cpDNA.

Structure of the chloroplast
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Organelles Plastids

• 9. Plastids
• (2) Leukoplasts store starch, sometimes
  protein or oils.

Structure of the chloroplast
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Organelles Plastids

• 9. Plastids
• (3) Chromoplasts store pigments associated
  with the bright colors of flowers and/or fruits.

Structure of the chloroplast
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Paramecium Cell

• Pond water
• protozoan single-celled animal

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Animal Cell









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Typical Eukaryotic Cell
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ANIMAL CELL
NUCLEOLUS
CELL MEMBRANE
NUCLEAR ENVELOPE
NUCLEAR PORE
MITOCHONDRION
CENTRIOLE
ENDOPLASMIC RETICULLLUM
CHROMATIN
RIBOSOME
GOLGI COMPLEX
LYSOSOME
MICROTUBULE
VACUOLE
CYTOPLASM
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Cells
Plant Cell
Animal Cell
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ell Movement

• Cell movement is both
• internal, referred to as cytoplasmic streaming
  and
• external, referred to as motility.

The cytoskeleton
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Cell Movement

• Internal movements of organelles are governed by
  actin filaments.
• These filaments make an area in which organelles
  such as chloroplasts can move

The cytoskeleton
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Cell Movement

• Internal movement is known as cytoplasmic
  streaming.
• External movement of cells is determined by
  special organelles for locomotion.

The cytoskeleton
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Cell Movement

• Cilia and flagella are similar except for length,
  cilia being much shorter.
• They both have the characteristic 9 2
  arrangement of microtubules.

The 92 arrangement of microtubules in a
flagellum or cilium
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Cell Movement

• Cilia from an epithelial cell in cross section
  (TEM x199,500). Note the 9 2 arrangement of
  cilia.

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Cell Movement

• Flagella work as whips pulling or pushing
  (dinoflagellates, a group of single-celled
  Protista) the organism through the water.

Movement of cilia and flagella
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Cell Movement

• Cilia work like oars on a viking longship
  (Paramecium has 17,000 such oars covering its
  outer surface).

Movement of cilia and flagella
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Cell Movement

• Pseudopodia are used by many cells, such as
  Amoeba, Chaos (Pelomyxa) and human leukocytes
  (white blood cells).

Formation and functioning of a pseudopod by an
amoeboid cell
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Cell Movement

• These are not structures as such but rather are
  associated with actin near the moving edge.

Click to Go to Quiz
Formation and functioning of a pseudopod by an
amoeboid cell
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Plasma Cell Membrane

• All cells have a 'skin', called the plasma
  membrane, protecting it from the outside
  environment. 
• The cell membrane regulates the movement of
  water, nutrients and wastes into and out of the
  cell. 

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Nucleus

• Inside of the cell membrane are the working parts
  of the cell. 
• At the center of the cell is the cell nucleus. 

• The cell nucleus contains the cell's DNA, the
  genetic code that coordinates protein synthesis. 
  

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Organelles

• In addition to the nucleus, there are many
  organelles inside of the cell -

• small structures that help carry out the
  day-to-day operations of the cell. 
•  

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Endoplasmic Reticulum

• The structure of membranous channels within
  eukaryotic cells which is the site of most
  protein and lipid biosynthesis

•  

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Ribosomes

• One important cellular organelle is the
  ribosome. 
•  

• Ribosomes participate in protein synthesis.  

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Mitochondria

• Another important cellular organelle is the
  mitochondrion. 

• Mitochondria (many mitochondrion) are often
  referred to as the power plants of the cell
  because many of the reactions that produce energy
  take place in mitochondria. 

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Lysosomes

• Also important in the life of a cell are the
  lysosomes.   

• Lysosomes are organelles that contain enzymes
  that aid in the digestion of nutrient molecules
  and other materials.

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The Golgi Apparatus

• Site of processing and separation of membrane
  components and secretory materials of the cell

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CELL STRUCTURE QUIZ

• There are ____ micrometers (µm) in one millimeter
  (mm). a) 1 b) 10 c) 100 d) 1000 e) 1/1000
• Human cells have a size range between ___ and ___
  micrometers (µm). a) 10-100 b) 1-10 c)
  100-1000 d) 1/10-1/1000

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CELL STRUCTURE QUIZ

• Chloroplasts and bacteria are ___ in size. a)
  similar b) at different ends of the size range
  c) exactly the same
• d) none of these.
• 4. The plasma membrane does all of these except
  ______. a) contains the hereditary material b)
  acts as a boundary or border for the cytoplasm
  c) regulates passage of material in and out of
  the cell d) functions in the recognition of self
  

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CELL STRUCTURE QUIZ

• Which of these materials is not a major component
  of the plasma membrane? a) phospholipids
• b) glycoproteins c) proteins d) DNA
• Cells walls are found in members of these
  kingdoms, except for ___, which all lack cell
  walls. a) plants b) animals c) bacteria d)
  fungi

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CELL STRUCTURE QUIZ

• The polysaccharide ___ is a major component of
  plan cell walls. a) chitin b) peptidoglycan c)
  cellulose
• d) mannitol e) cholesterol
• Plant cells have ___ and ___, which are not
  present in animal cells.
• a) mitochondria, chloroplasts b) cell
  membranes, cell walls c) chloroplasts, nucleus
  d) chloroplasts, cell wall

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CELL STRUCTURE QUIZ

• The ___ is the membrane enclosed structure in
  eukaryotic cells that contains the DNA of the
  cell.
• a) mitochondrion b) chloroplast
• c) nucleolus d) nucleus
• 10. Ribosomes are constructed in the ___. a)
  endoplasmic reticulum b) nucleoid c) nucleolus
  d) nuclear pore

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CELL STRUCTURE QUIZ

• 11. Rough endoplasmic reticulum is the area in a
  cell where ___ are synthesized. a)
  polysaccharides
• b) proteins c) lipids d) DNA
• 12. The smooth endoplasmic reticulum is the area
  in a cell where ___ are synthesized. a)
  polysaccharides
• b) proteins c) lipids d) DNA

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CELL STRUCTURE QUIZ

• 13. The mitochondrion functions in ____. a) lipid
  storage b) protein synthesis
• c) photosynthesis
• d) DNA replication e) ATP synthesis
• 14. The thin extensions of the inner
  mitochondrial membrane are known as _____. a)
  cristae b) matrix
• c) thylakoids d) stroma

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CELL STRUCTURE QUIZ

• 15. The chloroplast functions in ____. a) lipid
  storage b) protein synthesis c) photosynthesis
  
• d) DNA replication e) ATP synthesis
• 16. Which of these cellular organelles have their
  own DNA?
• a) chloroplast b) nucleus
• c) mitochondrion d) all of these

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CELL STRUCTURE QUIZ

• 17. The theory of ___ was proposed to explain the
  possible origin of chloroplasts and mitochondria.
  
• a) evolution b) endosymbiosis
• c) endocytosis d) cells
• 18. Long, whiplike microfibrils that facilitate
  movement by cells are known as ___.
• a) cilia b) flagella c) leather
• d) pseudopodia