Cytology

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Cytology

• The Study of Cells

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Relative sizes
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Cell Theory

• Basic unit of life
• Everything that organisms do is to keep the cells
  alive
• All living things are made of cells
• Cells come from other cells
• Smallest unit capable of life

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Life?

• Organization
• Metabolism use energy
• Homeostasis maintain conditions
• Growth/development
• Responsiveness
• Reproduction sexual and asexual
• Adaptation change as environment changes

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How Cells Are Studied

• Microscope 1 tool
• 1665 Robert Hooke Cells
• Two types of microscopes
• Light 1500x light passes through lens
• Electron Microscope electrons instead of light
  waves electromagnets aim electron beam

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How Cells Are Studied

• 3 types of electron microscopes
• Transmission Electron
  Microscope TEM electrons
  pass through subject, 100,000x
• Scanning Electron
  Microscope SEM electrons
  bounce off a thin gold plate
  on the surface of the object
  60,000x 3d
• Scanning-tunneling STM
  1,000,000 x

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How Cells Are Studied

• Cell Fractionation
• Disrupt cell centrifuge
  organelles to the bottom
• Pellet
• Separate and isolate pellets
• Study function independently

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Size of Cells

• Limited by surface area/volume
  ratio
• -Volume increases 8 x faster than
  S.A.
• - Problems with diffusion
• Limited by the amount of DNA
• DNA must be able to keep up with demands of the
  cytosol

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2 Types of Cells

• Prokaryote
• Bacteria
• No nucleus (nucleoid)
• No nuclear membrane
• No internal membranes
• No membrane-bound organelles
• Ribosomes

• Eukaryote
• Animal, plants, fungi, protists
• Nucleus (DNA)
• Nuclear membrane
• Internal membranes
• Membrane-bound organelles

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Nucleus

• Nucleus 2 parts
• DNA most of the cells
  genes
• Nuclear DNA
• Mitochondria and
  chloroplasts
• Nuclear envelope
• Phospholipid bilayer
• Pores

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Nucleus

• DNA
• Chromatin DNA wrapped around protein (histone)
• Chromosomes coiled, condensed chromatin
• Genes sections of DNA that code for proteins

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Nucleus

• Nucleolus large, obvious
  structure in non-dividing cells
• Ribosomes in production

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Ribosomes

• Protein synthesis
• No membrane
  (prokaryotes)
• Prokaryotes have slightly different
  ribosome molecular structure
  (tetracycline,
  streptomycin)
• Free ribosomes - float in cytosol
• Proteins within the cell muscle
• Bound ribosomes (ER)
• Proteins for secretion pancreas, liver, etc

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Endomembrane System

• System of folded internal membrane
• Endoplasmic reticulum
• Vesicles
• Golgi
• Lysosomes
• Vacuoles

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Endoplasmic Reticulum (ER)

• Folded membrane
• Network of tubules and
  sacs (cisternae)
• Continuous with outer
  nuclear membrane

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Endoplasmic Reticulum

• 2 types Smooth and Rough
• Smooth - Makes lipids, steroids, phospholipids
• Adrenal glands gonads, skin oil glands
• Detoxifies poisons/drugs

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Endomembrane System

• Rough ER make proteins

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Endomembrane System

• Vesicles membrane sacs that are pinched off
  portions of ER membranes moving from one membrane
  to another
• Secretory vesicles
  pancreas, salivary
  glands

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Golgi

• Stacked, flattened discs sacs (cisternae)
• Stores, modifies and routes products
  from ER
• Modifies proteins from
  ER
• Sorts products for
  secretion

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Endomembrane System

• Lysosomes digestive enzymes
• Tay-Sachs build up of lipids
• Arthritis release of hydrolytic enzymes
• Recycle - worn out organelles
• Remodeling - metamorphosis

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Endomembrane System

• Vacuoles membrane-bound sac
• 3 types and functions
• Food vacuole phagocytosis intracellular
  digestion
• Water vacuoles store water
• Contractile vacuole excrete
  water

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Central Vacuole

• Large vacuole found in plant cells
• Storage - minerals, water (turgor pressure),
  poisons
• Helps provide shape, support in plant
  cells

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Endo membrane System

• ER
• Vesicles
• Golgi
• Lysosomes
• Vacuoles

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Mitochondria

• Aerobic respiration
• Found in nearly all eukaryotic cells
  plants
• Number depends upon metabolic activity and cell
  type muscle, nerve, sperm
• DNA self-replicate
• Matrix
• Inner membrane Cristae
• Intermembrane space

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Plastids

• Plastids plant cells
• Chromoplast store pigments chromo color
  flowers
• Chloroplast
• Thylakoid
• Thylakoid space
• Grana
• Stroma

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Peroxisomes

• Organelle with enzymes
• Detoxification
• Alcohol (liver cells)
• Hydrogen peroxide waste product of cell
  metabolism

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Cytoskeleton

• Network of protein fibers within cytosol
• Function
• Framework
• Support
• Movement

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Cytoskeleton

• 3 parts
• Microtubules
• Microfilaments
• Intermediate filaments

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Microtubules

• Straight, hollow fibers
• Maintain structure, support
• Movement of organelles within the cell
• Spindle move chromosomes during mitosis
• Taxol, colchicine
• Poisons that interfere with microtubule formation
  - mitosis
• Taxol cancer treatment

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Microtubules

• Cilia short, hairlike, oarlike movement
• Flagella long few or one undulate

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Microfilament

• Actin filaments
• Smallest of cytoskeleton structure
• Muscle contraction
  (along with myosin)
• Elongation of pseudopodia in
  amoeba, macrophages
• Cleavage furrows during mitosis

Pseudopodia
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Intermediate Fibers

• Between microtubules and
  microfilaments in size
• Framework for cytoskeleton
• NOT disassembled, reassembled
  frequently
• ALS degeneration of intermediate filaments

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Plant Cell Surface

• Plant cells cell walls composed of cellulose
  within a matrix of polysaccharides and protein
• Fungi chitin
• Bacteria - peptidoglycans

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Cell Surface Plants

• Plasmodesmata linking channels between two
  plant cells
• Cell-to-cell communication one solid organism

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Intercellular Junctions

• Joints between cells (tissue formation)
• Plants - Plasmodesmata
• Animals
• Tight junctions
• Desmosomes
• Gap junctions

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Animal Cell Surface

• Glycocalyx sticky
  oligosaccharides
• Glues cells together, stick to
  lipids, proteins of adjacent
  cells
• Strength, identification with
  other cells

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Animal Cell Junctions

• Tight junctions cells closely knit together
  block intercellular junctions prevents
  intercellular fluid loss (brain block, tubular
  leakage)
• Epithelial tissues
• Cells are fused together

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Animal Cell Junctions

• Desmosomes - intercellular junctions that anchor
  one cell to the adjacent cell
• Also called anchoring junctions
• Strengthen linkages between cells
  skin cells

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Animal Cell Junctions

• Gap junctions channels between cells
• Allows substances to pass through, especially in
  tissues that need to communicate rapidly
• Heart muscle cells, liver, stem cells

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