CELLS

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CELLS

• The Fundamental Units of Life

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Cell Theory

• All organisms are composed of 1 or more cells.
• The cell is the basic living unit, providing
  organization for all organisms.
• All cells arise from preexisting cells.

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Cells Are Small

• Most are too small to be seen with the unaided
  eyeso Microscopes are used.
• A Light Microscope uses visible light shone
  through glass lenses.
• A thin section of specimen is required.
• van Leeuwenhoek

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Principles of Microscopy

• LIGHT
• REFRACTION
• MAGNIFICATION
• RESOLUTION

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MAGNIFICATION

• Image size exceeds real size.
• Achieved with convex lenses.
• There are limits
• involving the nature
• of light.
• First, you need enough
• light to penetrate the thin
• specimen.

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RESOLUTION

• Next, you need light of appropriate wavelengthor
  RESOLUTION is compromised.
• A measure of clarity of focus.
• Minimum distance between two points that allow
  the points to be distinguishable.
• Light microscopy not very useful below 0.2um.

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RESOLUTION
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Electron Microscopy

• Uses e- rather than light.
• Electrons have a much shorter wavelength.
• SEM Scanning Electron Microscopy
• TEM Transmission Electron Microscopy

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Electron Microscopy
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Cells!
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CELLS

• Eukaryotic Cells (animals, plants, fungi,
  protists)
• Complex relatively large.
• Membrane-bound nucleus organelles.
• 80-S Ribosomes.
• Prokaryotic Cells (archaea, bacteria)
• Simple relatively small.
• NO Membrane-bound nucleus organelles.
• 70-S Ribosomes.

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CELLS

• PROKARYOTIC EUKARYOTIC

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EUKARYOTIC CELLS
Organelles little organs (not really)
Membrane-bound
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ORGANELLES

• Nucleus
• Isolates the DNA provides access to its
  hereditary information.
• The control center of the cell (Transcription).

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Nucleus

• Nuclear Envelope (a double membrane)
• with Pores.
• Nucleolus
• rRNA
• Proteins
• Ribosomes
• Nucleoplasm
• with Chromatin/Chromosomes.

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Ribosomes

• Not true organelles, more structures.
• Protein factories.
• 2 sub-units.
• Free (in cytosol/cytoplasm), more for
  intracellular activities.
• Bound (on E.R.), often for extracellular
  activities (secretion) packaging within certain
  organelles.

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Endomembrane System

• Synthesis of Proteins their transport into
  membranes and/or organelles.
• Packaging of Proteins for transport out of the
  cell (secretion) or to other areas of the cell.
• Modification of Proteins.
• Transport of lipids, lipoproteins, glycoproteins,
  etc.

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Endomembrane System

• Endoplasmic Reticulum (E.R.)
• Rough E.R.
• Smooth E.R.
• Golgi Apparatus
• Vesicles
• Lysosomes
• (also, nuclear envelope, vacuoles, and plasma
  membrane)

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Endoplasmic Reticulum

• Network of interconnected membranes (continuous
  with the nuclear envelope).
• Flattened or tubular Cisternae.

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Rough E.R.

• The site of protein synthesis, particularly
  secretory proteins.
• Initial modification of proteins.
• Especially, formation of Glycoproteins.
• Formation (budding) of Transport Vesicles.
• Formation of NEW Membrane
• Phospholipid Synthesis

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Smooth E.R.

• Formation of Lipids, detoxification.
• Lipid-derived hormones (steroids) are
  synthesized, including sex hormones
  (testosterone, etc.) in certain glands.
• Solubilization of toxins (drugs, alcohol,
  caffeine, etc. ) in liver cells.
• Calcium ion storage release in muscle cells.

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Golgi Apparatus

• Manufacture, storage, modification, sorting,
  shipping of ER-produced items (esp. secretion).
• Addition of non-protein portions to protein
  molecules.

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Golgi Apparatus

• Stacks of cisternae, with cis trans faces.
• Cis receiving (takes in vesicles).
• Trans sending (gives rise to vesicles).

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Lysosomes

• Vesicles carrying digestive enzymes hydrolytic
  (proteolytic) enzymes.
• Animal Cells.
• Digestion of food brought in by phagocytosis.

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Lysosomes

• Digestion and recycling of old damaged
  organelles within the cell Autophagy.

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Endomembrane System
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Vacuoles

• Large vesicles with particular functions.
• Food Vacuoles.
• Contractile Vacuoles.
• Central Vacuole w/ tonoplast in Plant Cells.

• Storage.
• Dissolved Solutes.
• Dumping Ground.
• Protection.
• Shape.

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Mitochondrion

• Site of cellular respiration energy production.
• Carbohydrates ATP
• Not part of endomembrane system.
• Have their own DNA, RNA, Proteins, and Ribosomes
  (70-S).
• Grow and reproduce independently.
• Animals, Plants, Fungi, Protists.

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Mitochondrion

• Surrounded by a double membrane an envelope.

Outer Membrane Inner membrane (Cristae) Matrix
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Chloroplast

• Site of Photosynthesis acquisition of chemical
  energy from sunlight.
• Sunlight CO2 Carbohydrates
• A plastid (not part of endomembrane system).
• Have their own DNA, RNA, Proteins, and Ribosomes
  (70-S).
• Grow and reproduce independently.
• Plants, Protists.

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Chloroplast

• Surrounded by a double membrane an envelope.

Inner Membrane (Grana composed of stacked
Thylakoids)
Outer Membrane
Stroma
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Peroxisomes

• Odd vesicles that carry Hydrogen to Oxygen,
  forming Hydrogen Peroxide (H2O2).
• Used to break down larger molecules.
• Detoxify alcohol in Liver Cells.

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Cytoskeleton

• Fiber-like structures that lend organization.
• Support (providing a scaffolding onto which
  organelles vesicles can be organized).
• Shape (maintain particular shape depending on the
  cells location and/or function).
• Transport of materials around or out of the cell.
• Motility of the whole cell from one location to
  another.

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Cytoskeleton

• Microtubules Microfilaments Intermediate
  Filaments

Keratin Subunits
Tubulin
Actin
Keratin
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Cytoskeleton

• Permanent
• Flagella
• Cilia
• Muscle Contraction
• Scaffolding Shape Maintenance

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Cytoskeleton

• Transient
• Spindle Fibers
• Transport filaments

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Cell Wall

• OUTSIDE the Cell Membrane (technically, outside
  the cell!)
• Various proteins glycoproteins in Prokaryotes.
• Cellulose in Plants.
• Chitin in Fungi.

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Eukaryotic Cell
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Endosymbiont Theory
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Onion Cells