Ch. 6 Warm-Up

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Ch. 6 Warm-Up

1. What are the 2 main types of cells? Which Domains
   do they consist of?
2. List 3 ways that eukaryotes differ from
   prokaryotes.

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Ch. 6 Warm-Up

1. How is the size of a cell related to its
   function?
2. Name 5 organelles or cell structures and their
   function.

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Warm-Up Activity

• Pick up handout on back counter.
• Complete this handout for your warm-up activity.

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Ch. 6 Warm-Up
Compare and contrast Animal vs. Plant Cells
Animal Cell Plant Cell

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Ch. 6 Warm-Up

• What is the structure function of
• Microtubules
• Microfilaments
• Intermediate filaments

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Ch. 6 Warm-Up

• What is the function of
• Plasmodesmata
• Gap junctions
• Tight junctions
• Desmosomes

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Chapter 6

• A Tour of the Cell

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You Must Know

• Three differences between prokaryotic and
  eukaryotic cells.
• The structure and function of organelles common
  to plant and animal cells.
• The structure and function of organelles found
  only in plant cells or only in animal cells.

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How We Study Cells
Biologists use microscopes and the tools of
biochemistry to study cells
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Size range of cells
Note that light microscopes can not magnify as
well as electron microscopes
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Light Microscopy (LM) vs. Electron Microscopy (EM)
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Comparisons of Scopes

• Light

• Electron

• Visible light passes through specimen
• Refracts light so specimen is magnified
• Magnify up to 1000X
• Specimen can be alive/moving
• Color

• Focuses a beam of electrons through/onto specimen
• Magnify up to 1,000,000 times
• Specimen non-living and in vacuum
• Black and white

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Electron Microscopy

• Transmission (TEM)

• Scanning (SEM)

• 2-D
• Creates a flat image with extreme detail
• Can enhance contrast by staining atoms with heavy
  metal dyes

• 3-D
• Used for detailed study of surface of specimen
• Gives great field of depth

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Studying cell structure function

1. Cell fractionation - take apart cells, separate
   major organelles
2. Ultracentrifuge - applies force 1 million times
   the force of gravity to separate further the cell
   organelles with the most dense at the bottom

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2 Types of Cells

1. Prokaryotes Domain Bacteria Archaea
2. Eukaryotes (Domain Eukarya) Protists, Fungi,
   Plants, Animals

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A Prokaryotic Cell (bacteria)
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Prokaryote Vs. Eukaryote

• before kernel
• No nucleus
• DNA in a nucleoid
• Cytosol
• No organelles other than ribosomes
• Small size
• Primitive
• i.e. Bacteria Archaea

• true kernel
• Has nucleus and nuclear envelope
• Cytosol
• Membrane-bound organelles with specialized
  structure/function
• Much larger in size
• More complex
• i.e. plant/animal cell

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Cell Size and Scale

• http//learn.genetics.utah.edu/content/begin/cells
  /scale/
• Scale of the Universe
• http//www.onemorelevel.com/game/scale_of_the_univ
  erse_2012

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• Cells must be small to maintain a large surface
  area to volume ratio
• Large S.A. allows ? rates of chemical exchange
  between cell and environment

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Surface Area Example (Animal)

• Small Intestine highly folded surface to
  increase absorption of nutrients
• Villi finger-like projections on SI wall
• Microvilli projections on each cell

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Folds ? Villi ? Microvilli
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Surface Area Example (Plant)

• Root hairs extensions of root epidermal cells
  increase surface area for absorbing water and
  minerals

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Nucleus

• Function control center of cell
• Contains DNA
• Surrounded by double membrane (nuclear envelope)
• Continuous with the rough ER
• Nuclear pores control what enters/leaves nucleus
• Chromatin complex of DNA proteins makes up
  chromosomes
• Nucleolus region where ribosomal subunits are
  formed

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Nucleus

• Contains DNA
• Function control center of cell
• Surrounded by double membrane (nuclear envelope)
• Continuous with the rough ER
• Nuclear pores control what enters/leaves nucleus
• Chromatin complex of DNA proteins makes up
  chromosomes
• Nucleolus region where ribosomal subunits are
  formed

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Ribosomes

• Function protein synthesis
• Composed of rRNA protein
• Large subunit small subunit
• Types
• Free ribosomes float in cytosol, produce
  proteins used within cell
• Bound ribosomes attached to ER, make proteins
  for export from cell

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Endomembrane System

• Regulates protein traffic performs metabolic
  functions

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Endoplasmic Reticulum (ER)

• Network of membranes and sacs
• Types
• Rough ER ribosomes on surface
• Function package proteins for secretion, send
  transport vesicles to Golgi, make replacement
  membrane
• Smooth ER no ribosomes on surface
• Function synthesize lipids, metabolize carbs,
  detox drugs poisons, store Ca2

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Endoplasmic Reticulum (ER)
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Golgi Apparatus

• Function synthesis packaging of materials
  (small molecules) for transport (in vesicles)
  produce lysosomes
• Series of flattened membrane sacs (cisternae)
• Cis face receives vesicles
• Trans face ships vesicles

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Lysosomes

• Function intracellular digestion recycle cells
  materials programmed cell death (apoptosis)
• Contains hydrolytic enzymes

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Vacuoles

• Function storage of materials (food, water,
  minerals, pigments, poisons)
• Membrane-bound vesicles
• Eg. food vacuoles, contractile vacuoles
• Plants large central vacuole -- stores water,
  ions

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Parts of plant animal cell p 108-109
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Mitochondria

• Function site of cellular respiration
• Double membrane outer and inner membrane
• Cristae folds of inner membrane contains
  enzymes for ATP production increased surface
  area to ? ATP made
• Matrix fluid-filled inner compartment

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Chloroplasts

• Function site of photosynthesis
• Double membrane
• Thylakoid disks in stacks (grana) stroma (fluid)
• Contains chlorophylls (pigments) for capturing
  sunlight energy

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Illustrative Examples

• Variations within molecules provide a wider range
  of functions
• Chlorophylls

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Endosymbiont theory

• Mitochondria chloroplasts share similar origin
• Prokaryotic cells engulfed by ancestors of
  eukaryotic cells
• Evidence
• Double-membrane structure
• Have own ribosomes DNA
• Reproduce independently within cell

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Peroxisomes

• Functions break down fatty acids detox alcohol
• Involves production of hydrogen peroxide (H2O2)

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Cytoskeleton network of protein fibers

• Function support, motility, regulate biochemical
  activities

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3 Types of Cytoskeleton Fibers
Microtubules Microfilaments Intermediate Filaments

• Protein tubulin
• Largest fibers
• Shape/support cell
• Track for organelle movement
• Forms spindle for mitosis/meiosis
• Component of cilia/flagella

• Protein actin
• Smallest fibers
• Support cell on smaller scale
• Cell movement
• Eg. ameboid movement, cytoplasmic streaming,
  muscle cell contraction

• Intermediate size
• Permanent fixtures
• Maintain shape of cell
• Fix position of organelles

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3 Types of Cytoskeleton Fibers
Microtubules Microfilaments Intermediate Filaments
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• Centrosomes region from which microtubules grow
• Also called microtubule organizing center
• Animal cells contain centrioles

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Cilia Flagella

• Flagella long and few propel through water
• Cilia short and numerous locomotion or move
  fluids
• Have 92 pattern of microtubules

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Extracellular Matrix (ECM)

• Outside plasma membrane
• Composed of glycoproteins (ex. collagen)
• Function Strengthens tissues and transmits
  external signals to cell

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Intercellular Junctions (Animal cells)

• Tight junctions 2 cells are fused to form
  watertight seal
• Desmosomes rivets that fasten cells into
  strong sheets
• Gap junctions channels through which ions,
  sugar, small molecules can pass

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Plant Cells

• Cell wall protect plant, maintain shape
• Composed of cellulose
• Plasmodesmata channels between cells to allow
  passage of molecules

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Plant Cells Only Animals Cells Only
Central vacuoles Lysosomes
Chloroplasts Centrioles
Cell wall of cellulose Flagella, cilia
Plasmodesmata Desmosomes, tight and gap junctions
Extracellular matrix (ECM)
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Harvard cell video

• http//multimedia.mcb.harvard.edu/anim_innerlife.h
  tml