Structure

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The Cell

• Structure
• Of
• The
• Cell

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Cell History

• Robert Hooke is credited with the discovery of
  the cell. (1665)
• Leeuwenhoek ( About 1700) He developed
  microscopes and glasses. He was the first to
  look at microscopic life. He looked at ditch
  water and discovered amimalicules.
• Schleinden Concluded all plants are made out
  of cells. (Late 1830s)
• Schwann Concluded all animals are made out of
  cells. (Late 1830s)
• This led to the..

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The Cell Theory

• ALL LIVING THINGS ARE MADE OUT OF CELLS.
• CELLS ARE THE BASIC UNIT OF STRUCTURE AND
  FUNCTION IN AN ORGANISM.
• CELLS COME ONLY FROM PRE-EXISTING CELLS.

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Francesco Redi
At the time, prevailing wisdom was that maggots
formed naturally from rotting meat. In the
experiment, Redi took three jars and put meat in
each. He tightly sealed one, left one open, and
covered the top of another with gauze. He waited
for several days, and saw that maggots appeared
on the meat in the open jar, but not in the
sealed one, and maggots did not hatch on the
gauze covered jar.

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What is a Cell?

• The smallest unit that can carry out all the
  functions necessary to define life.
• Storing and releasing energy.
• Building and repairing cell parts.
• Obtaining nutrients.
• Expelling wastes.
• Responding to the environment.
• Reproducing.

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Types of Cells

• Prokaryotic Cells The most ancient life form on
  Earth. They have been in existence for at least
  3.5 billion years. These cells lack a true
  nucleus, and contain a single circle of DNA
  called a plasmid. Bacteria are prokaryotic
  cells.
• Eukaryotic Cells A large, complex cell that
  contains a membrane bound nucleus. This nucleus
  houses chromosomes, the blueprints for life.

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PROKARYOTIC CELLS
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EUKARYOTIC CELLS
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Common Characteristics of Cells

• Both prokaryotic and eukaryotic cells have a cell
  membrane.
• The interior of both types of cells is mainly
  composed of a fluid environment called cytoplasm.
  
• Both types of cells contain ribosomes, which are
  responsible for building proteins.

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Eukaryotic Cell Organelles

• The cytoplasm of eukaryotic cells have various
  structures suspended within them.
• The CYTOSOL is the aqueous (liquid) space within
  the cytoplasm.
• Many types of cell ORGANELLES are suspended
  within the cytoplasm, each with a unique function.

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TYPES OF CELL ORGANELLES
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Cell Membrane

• A thin, flexible envelope that surrounds the
  cell.
• Found in all true cells.
• Controls boundaries for the cell, maintains
  homeostasis and movement of material in and out
  of a cell.
• Contains pores.

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More About Cell Membranes

• Three Types of membranes.
• Permeable Everything enters.
• Non-permeable Nothing enters.
• Semi-permeable Selective entrance/exit of
  materials.

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Cytoplasm

• A constantly moving jelly-like fluid that lies
  between the cell nucleus and the cell membrane.
  All the organelles are suspended within this
  medium.

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Nucleus

• The brain of the cell. Controls all cell
  activities.
• Contains nucleic acids.
• DNA Stores information needed to make proteins
  for cell growth and repair and the genetic
  blueprints for reproduction.
• RNA Reads DNA codes and guides the protein
  making process. RNA is able to leave the nucleus.

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Nuclear Membrane

• The structure/border that separates the nucleus
  from the cytoplasm and other organelles suspended
  within the cytoplasm.

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Chromosomes

• A cell organelle composed of tightly coiled DNA
  wound around a protein core.
• Chromosomes are threadlike in shape.
• They carry the genetic blueprints within the
  nucleus.

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Nucleolus

• Called the Little Nucleus housed within the
  nucleus.
• The nucleolus contains and makes the RNA that
  functions as the cell messengers of protein
  construction.

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Endoplasmic Reticulum

• Tubular passages that lead out from the nuclear
  membrane.
• Studded with ribosomes.
• Transports proteins to various parts of the cell.
• May also connect to the cell membrane.

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Ribosomes

• Active in protein synthesis.
• Made up of special RNA.
• rRNA
• tRNA
• mRNA
• Generally found attached to the Endoplasmic
  Reticulum, but some are found floating within the
  cytoplasm.

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Golgi Bodies

• Assists in further processing proteins.
• Packs proteins into vesicles.
• Makes the lysosomes.

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Lysosome

• Contains digestive enzyemes.
• Breaks down large food particles into useable
  portions for the mitochondria.
• Much more prominent in animal cells than plant
  cells.

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Mitochondria

• Rod-shaped structures called the powerhouse for
  the cell.
• Breaks down sugar (glucose) to release energy for
  life functions.
• The more active a cell is, the more mitochondria
  they have.

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Vacuoles

• Large, spherical, water filled sacs that store
  food and wastes.
• Small and few in animal cells.
• Large and prominent in plant cells.

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Centrioles

• Present during cell reproduction.
• Duplicates during cell reproduction.
• Helps to pull the cell apart during cell
  division.

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Microtubules

• The cell skeleton.
• Provides a support system for the cell.
• Composed of tubes of protein.

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Cell Wall

• Found only in plant cells.
• A rigid wall of cellulose and protein that
  surrounds the cell membrane.
• Strengthens and supports plant cells.
• Gives cells and more box-like shape.

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Chloroplasts

• Found within plant cells.
• Contains the green pigment chlorophyll.
• Sites of photosynthetic activity.

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Cilia or Flagella

• Hair-like projections.
• Aids in cell movement.
• Undulating
• Whip-like
• Oar fashion.