Cell Structure

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Cell Structure

• Organelles

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Recall the Characteristics of Life

• All Living things share the following
• Cells
• Organization
• Energy use
• Homeostasis
• Growth/Development
• Reproduction

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The Cell Theory

• Cells are the only characteristic that cannot be
  found in non-living things. Because of their
  importance, much cell research has taken place
  and been compiled into the cell theory
• All living things 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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2 Levels of Organization

• Molecular and Cellular
• Macromolecules are organized into structures
  called organelles. Organelles working together
  make up a cell.
• One cell has all it needs to carry out all life
  processes.
• The organelles carry out all of the functions of
  life.

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How is a single, tiny little cell able to do so
much?

• Each organelle in the cell performs a specific
  function.
• Remember, all cells have
• A cell membrane
• DNA (genetic information)
• cytoplasm
• Only eukaryotic cells have a nucleus and other
  membrane-bound organelles.

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Macromolecules

• Four macromolecules make up all the organelles
• Proteins
• Lipids (fats)
• Nucleic Acids
• Carbohydrates

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CELL MEMBRANE

• STRUCTURE Organized in a bilayer.
  Outer portion is hydrophilic and inner is
  hydrophobic. Mostly made of lipids
  (phospholipids) and proteins.

FUNCTION the cell membrane surrounds the
cytoplasm of a cell and physically separates the
inside of the cell from the outside environment.
Allows needed materials to pass through.
Analogy security guard or border control
Found in ALL cells (prokaryotic and eukaryotic)
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Cheek Cell
Cell Membrane
Nuclear membrane
Nucleus
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CELL WALL

• Function Gives cells Rigidity and Strength, and
  offers protection and overall provides skeletal
  support.
• Structure Composed of cellulose, a type of
  carbohydrate. The structure is rigid, yet
  flexible, and it will bend rather than hold a
  shape, like when a plant wilts.

Analogy Brick walls of a builiding
Found in Prokaryotic and Plant cells
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Cell Wall
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The cytoplasm contains the organelles of a cell

• Structure The cytoplasm is the region of the
  cell between the membrane and the nucleus. It
  consists of a gelatin-like fluid which bathes
  the organelles.
• It is a solution with dissolved salts, minerals,
  etc.
• Function Region where most of the cells
  activities are carried out.

Analogy Jell-O with fruit pieces in it
Found in ALL Cells
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Cytoplasm
Cytoplasm
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Mitochondria

• Structure Mitochondria has two membranes. The
  outer membrane is smooth. The inner membrane is
  folded to allow more room for chemical reactions
  to occur.
• Function Mitochondria break down compounds from
  food to release usable energy for the cell

Analogy Power Plant- converts energy to a usable
form.
Found in Plant and Animal Cells
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Cytoplasm
Mitochondria
Cell Membrane
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Ribosomes

• Function-Ribosomes are responsible for
  translating code from mRNA and making proteins.

• Structure- Ribosomes are made up of proteins and
  RNA and consist of two parts, a large subunit and
  a small subunit. Some are attached to the
  endoplasmic reticulum others float freely in the
  cytoplasm.

Found in ALL cells
Analogy Construction workers
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Ribosome
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Ribosomes
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Function Transports materials within cells (an
intracellular highway)-Rough ER has a role in
protein synthesis-Smooth ER synthesizes (makes)
lipids, breaks down toxic substances
Endoplasmic Reticulum
Structure Membranous network of sac-like
structures that are connected by cytoskeleton
(Rough ER has ribosomes on it)
Analogy factory conveyor belts, machines, etc.
Found in Plant and Animal Cells
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Golgi Body

• Structure It is a network of flattened and
  stacked membrane-bound sacs found within cells
• Function The golgi body stores, packages, and
  distributes the proteins and lipids made in the
  endoplasmic reticulum

Analogy shipping department, Post Office
Found in Plant and Animal Cells
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Rough ER
Ribosome
Golgi Body
Smooth ER
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Lysosomes

• Structure- lysosomes are spherical organelles
  contained by a single-layer membrane containing
  digestive enzymes inside
• Function- Lysosomes contain the enzymes for
  breakdown of worn out cell parts.

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Lysosomes

• Analogy garbage/waste disposal.
• Found in Plant and Animal Cells

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Lysosomes
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Cytoskeleton

• Functions- It maintains the cells shape and
  helps in the movement of the organelles.
• Structures- Flexible scaffold-like structure made
  up of microfilaments, microtubules, and proteins.
• Analogy frame of a car/house.
• Found in ALL cells

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Cytoskeleton
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Nucleus
Structure It has a double-layered membrane. It
has large pores through which materials pass back
and forth.

• Function The nucleus directs all activity in the
  cell, controls the growth and reproduction of the
  cell, and contains the blueprints of the cell in
  the DNA.
• Analogy county office that stores the original
  building blueprints. Brain, stores info and
  sends out messages.
• Found in Plant and Animal Cells

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Nuclear membrane
Nucleus
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Cilia

• FUNCTION
• The cilia generate water currents
• STRUCTURE
• In eukaryotic cells, cilia and flagella contain
  proteins and microtubules, which are composed of
  linear polymers of globular proteins called
  tubulin.

Analogy cilia are like fans
Cilia found in Animal Cells
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Cilia
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Flagella

• FUNCTION
• Flagella are used primarily for movement of
  single cells.
• STRUCTURE
• In eukaryotic cells, cilia and flagella contain
  proteins and microtubules, which are composed of
  linear polymers of globular proteins called
  tubulin.

Analogy flagella are like boat rudders
Flagella found in Animal and Prokaryotic Cells
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Flagella
Animal Sperm Cell
Prokaryotic Bacterial Cell
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Animal and Plant Cells Share Many Structures in
Common
Animal Cell
Plant Cell
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Plant cells and Animal cells have some key
differences

• A cell wall
• Vacuole
• Plastids (Chloroplasts)

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Vacuole
Structure Large sac surrounded by a
membrane Function Stores salts, minerals,
nutrients, water, etc. and plays an important
structural role for plants Analogy Warehouse
Found in Plant cells and animal cells (very
tiny)
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Plastids (Chloroplasts)

• Structure Surrounded by double-membrane,
  contains chlorophyll
• Function contain pigments, capture energy from
  the sun to make organic compounds (food), may
  store food (starch)
• Analogy solar panels
• Found in Plant cells

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Cell Wall
Chloroplast
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Cell Wall
Nucleus