Cells Structure and Function

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Cells Structure and Function
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Cells, the units of structure and function of
living organisms, come in two main categories
based on their structural complexity.

• Prokaryotic cells are small and simple do not
  have a nucleus to store DNA, the genetic
  material and lack membrane bound organelles.
• Eukaryotic cells are large and complex DNA is
  stored in a nucleus, and there are many membrane
  bound organelles to conduct the functions of the
  cell.

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All Organisms Are Composed of Cells
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Prokaryotic Organisms

• Bacteria and Archea are prokaryotic organisms.
• Unicellular and very simple, these prokaryotic
  organisms are vital to life on Earth due to their
  roles in ecosystems.
• Prokaryotic cells have ribosomes to make proteins
  and their DNA is in a nucleoid region.
• Pilli and flagella function for attachment and
  motility

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In Eukaryotic Organisms Cells Have Organelles

• Unicellular Protists
• Multicellular Animals, Plants, Fungi
• Eukaryotic cells are compartmentalized to
  increase metabolic efficiency. They contain many
  cellular organelles to conduct specific
  functions.
• Organelles have the surface area (room required
  to carry out work) and the materials required for
  specific functions of the cell.

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All Eukaryotic Cells Have Similarities

• All eukaryotic cells have many membrane bound
• organelles in common.
• Plasma membrane cells outer boundary
• Nucleus site of DNA replication and
  transcription
• Endoplasmic Reticulum involved in synthesis and
  transport
• Mitochondria site of intracellular cellular
  respiration
• Gogi apparatus involved in chemical
  modification and packaging
• Cytoskeleton involved in structure and motility

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Plasma Membrane

• The plasma membrane is found in all types of
  cells.
• It is the boundary (border), which defines the
  cell.
• It controls the entrance and exit of materials.
• It provides surface area for many of the cells
  enzymatic functions.
• Organelles have membranes, which are very similar
  to the plasma membrane.

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Nucleus

• The nucleus houses DNA, the genetic material.
• The nucleus contains an organelle, the nucleolus,
  which deals with RNA.
• The nucleus has pores that selectively allow the
  entrance and/or exit of substances

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Two Types of Endoplasmic Reticulum

• RER is the Rough
• Endoplasmic Reticulum, which has ribosomes.
• Within the RER proteins are modified into
  functional proteins and packed into transport
  vesicles.
• SER is the Smooth Endoplasmic Reticulum, which
  has no ribosomes. Within the SER lipids are
  synthesized. It also detoxifies substances. It
  stores Calcium ions for muscle contractions

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Gogi Apparatus/Body/Complex

• Receives and modifies substances synthesized in
  the endoplasmic reticulum.
• Substances are packaged into vesicles to be used
  by the cell or transported out of the cell.

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Lysosomes

• Lysosomes contain enzymes that fuse with food
  vacuoles for digestion.
• Within white blood cells of the immune system,
  enzyme filled lysosomes fuse with bacteria filled
  vacuoles and digest the bacterial cells.
• Lysosomes fuse with waste vacuoles or vesicles
  and recycle, salvageable materials for the cell.

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Vacuoles

• Vacuoles are storage vesicles, which may contain,
  water, wastes, toxins, food, chemicals, and any
  other materials that the cells need to store.
• Vacuoles are essential to maintain homeostatic
  balance in cells
• Vacuoles increase the efficiency of the cells by
  providing a high degree of compartmentalization .

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Endomembranes

• Together, the nuclear envelope the endoplasmic
  reticulums, both smooth and rough, the Gogi
  Apparatus vesicles lysosomes and vacuoles
  compose the endomembrane system of the cell. All
  of these organelles are physically or
  strategically connected and function in tandem
  and synchrony.

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Mitochondria

• Two main stages of cellular respiration, the
  Krebs Cycle and the Electron Transport Chain,
  occur in the mitochondria in order to transform
  energy from the food that organisms eat into
  chemical energy in the bonds of ATP.

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Cytoskeleton

• Composed of fibrous proteins of various
  diameters, the cytoskeleton is responsible for
  support and movement of organelles and the cell.

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Ribosomes

• Ribosomes are not membrane bound organelles.
  Rather they are composed of rRNA.
• Ribosomes are involved in the synthesis of
  proteins along with other types of RNA, mainly
  mRNA and tRNA.
• Ribosomes are found in both eukaryotic and
  prokaryotic cells.

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Cells Are Models of Organization and Efficiency

• Cells illustrate the principle of emergent
  properties
• the whole is greater than the individual part.