SNC 2D1

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SNC 2D1

• The Cell Theory
• Structure Function of the Cell

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Cellular Organization

• Cell
• Tissue group of cells functioning together.
• Organ group of tissues functioning together.
• Organ System group of organs functioning
  together.
• Organism group of organ systems functioning
  together.

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The History of the Cell

• The Cell
• The basic unit of an organism
• Discovery made possible by the invention of the
  microscope

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Microscopes and Cells

• 1600s.
• Anton van Leeuwenhoek first described living
  cells as seen through a simple microscope.

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Microscopes and Cells

• Robert Hooke used the first compound microscope
  to view thinly sliced cork cells.

• Hooke was the first to use the term cell.
• Compound scopes use a series of lenses to magnify
  in steps.

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Microscopes and Cells

• 1830s
• Mathias Schleiden identified the first plant
  cells and concluded that all plants are made up
  of cells.
• Thomas Schwann made the same conclusion about
  animal cells.

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The Cell Theory

• All living things are composed of one or more
  cells.
• The cell is the smallest entity that retains the
  property of life.
• New cells arise only from pre-existing cells.
• The life properties of an organism depend on the
  life properties of its individual cells.

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Two Basic Cell Types

• Prokaryote
• Lacks internal compartments.
• No membrane bound organelles.
• No true nucleus.
• Most are single-celled (unicellular) organisms.
• Single circular loop of DNA
• Ribosomes
• Examples bacteria

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nucleoid (DNA)
ribosomes
food granule
prokaryotic flagellum
plasma membrane
cell wall
cytoplasm
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Two Basic Cell Types

• Eukaryote
• Has several internal structures (organelles).
  Most organelles are enclosed by a membrane
• True nucleus. Larger nucleus.
• DNA is organized into linear chromosomes
• Can be either unicellular or multicellular.
• Unicellular example yeast
• Multicellular examples plants, animals and fungi

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chromatin (DNA)
nucleus
nucleolus
nuclear envelope
flagellum
intermediate filaments
cytoplasm
plasma membrane
rough endoplasmic reticulum
ribosome
lysosome
microtubules
smooth endoplasmic reticulum
Golgi complex
free ribosome
vesicle
mitochondrion
vesicle
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microtubules (part of cytoskeleton)
mitochondrion
chloroplast
Golgi complex
central vacuole
smooth endoplasmic reticulum
vesicle
cell wall
rough endoplasmic reticulum
plasma membrane
nucleolus
nuclear pore
nucleus
chromatin
nuclear envelope
intermediate filaments
free ribosome
ribosomes
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Similarities of Plants and Animal Cells

• Both constructed from eukaryotic cells
• Both contain similar organelles
• Both surrounded by cell membrane

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Differences of Plants and Animal Cells

• Plants have
• Cell wall made of cellulose provides strength
  rigidity
• Have chloroplasts, so are photosynthetic
• Animals have
• Other organelle not found in plants (lysosomes
  formed from Golgi Bodies)
• Centrioles, important in cell division
• Fungi have
• Cell wall made of chitin

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The Parts of The Eukaryotic Cell

• Plasma Membrane (Cell Membrane)
• Serves as a boundary between the cell and
  its external environment.
• Allows materials to pass in and out of the cell.

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• Cell Wall
• Surrounds the plasma membrane of the cells of
  plants, bacteria, and fungi.
• Plant cell walls contain cellulose while fungi
  cell walls contain chitin.

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• Nucleus
• Regulates cell function, is the control centre of
  the cell.
• Surrounded by a double-layered membrane (nuclear
  enveloped) with large pores that allow materials
  to pass in and out of the nucleus.
• Contain nucleoli synthesizes ribosomal RNA
• Contains chromatin long tangles of DNA.

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• Nucleolus
• Darker structure inside the nucleus.
• Responsible for ribosome production.
• Ribosomes are the sites of protein production.

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nuclear envelope
nucleolus
nuclear pores
chromatin
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nucleus
nuclear pores
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• Cytoplasm
• The jelly-like polysaccharide (sugar) material
  that surrounds the organelles.
• Mostly made of water.

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• Endoplasmic reticulum
• Folded membrane that acts as the cells delivery
  system. Attached to nucleus.
• Smooth E.R. contains enzymes for lipid synthesis.
• Rough E.R. is studded with ribosomes for protein
  synthesis and secretion.

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rough endoplasmic reticulum
ribosomes
0.5 micrometers
smooth endoplasmic reticulum
0.5 micrometers
vesicles
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• Ribosomes
• Assemble amino acids into polypeptide chains
• Associated with the E.R.
• Composed of nucleic acids (DNA-like material)

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Ribosomes (small dots)
rough endoplasmic reticulum (tubes)
0.5 micrometers
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vesicles
smooth endoplasmic reticulum
0.5 micrometers
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• Golgi apparatus (or Golgi body)
• A series of flattened sacs where newly made fats
  and proteins from the E.R. are repackaged and
  shipped to the plasma membrane.
• (Lysosomes are Golgi-derived vesicles, containing
  digestive enzymes.)

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vesicles from ER
Golgi complex
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• Vacuoles
• A sac of fluid surrounded by a membrane used to
  store food, fluid, or waste products.
• In plants, a large water vacuole takes up much of
  the space inside the cell
• These water vacuoles provide water pressure
  (Turgor pressure) that helps keep the cells rigid
  without it, plants would wilt.

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• Lysosomes
• Contain a digestive enzyme.
• Can fuse with vacuoles to digest food, or can
  digest worn cell parts.
• Also known as suicide sacs because they can
  also destroy the whole cell.

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• Mitochondria
• Produce the energy for the cell.
• Also known as the powerhouse of the cell.
• Has a highly folded inner membrane (cristae).
• Have their own DNA and ribosomes self replicate
• Found in cells of all eukaryotes (plants, animals
  and fungi)

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• Chloroplasts
• Found in plant cells and some protists.
• Transforms light energy into chemical energy
  which is stored in food molecules.
• Contain chlorophyll a green pigment that traps
  light energy and gives plants their green color.
• stroma/grana (thylakoid stacks)
• Have their own DNA and ribosomes self
  replicate

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• Cilia
• Short, numerous, hair-like projections from the
  plasma membrane.
• Move with a coordinated beating action.

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• Flagella
• Longer, less numerous projections from the plasma
  membrane.
• Move with a whiplike action.

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• Centrioles
• made of protein.
• play a role in the splitting of the cell into two
  cells.
• found in animal and fungi cells.

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Cell Size

• Range from 1100µm
• Why is there a limit to cell size?
• Surface-to-volume ratio gets too small
• Affects distance from surface to center

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