Cell Structure

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Ch 7- Cell Structure and Function
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Discovery of Cells

• 1665 Robert Hooke noticed thousands of tiny
  chambers while looking at cork
• He named these cells because they looked like
  the small chambers of his monastery

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Around the same time...

• Anton van Leeuwenhoek noticed a world of tiny
  organisms were everywhere, including his water

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The cell theory

• Matthias Schleiden concluded that all plants were
  made of cells
• Theodore Schwann stated all animals are made up
  of cells
• Virchow concluded new cells are made from
  existing cells

Woo HOO!
Nice work!
So Smart!
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Soooooooo...

• All living things are composed of cells
• Cells are the basic unit of structure and
  function in living things
• New cells come from other cells

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Prokaryotes vs. Eukaryotes
Eukaryotes HAVE a nucleus!
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Prokaryotes

• Do not contain a nucleus
• Are smaller and simpler
• Carry out every activity associated with living
  things
• Like bacteria!

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Which one am I ???
Eukaryote
Prokaryote
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Eukaryotes

• Usually larger and more complex
• Highly specialized
• Genetic material is separated from the rest of
  the cell in a nucleus
• Can be a single cell or multicellular organism

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Examples
Plants
Protists
Fungi
Animals
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Eukaryotic cell structure

• Made up of organelles or little organs
• Divided into 2 parts nucleus cytoplasm
• Cytoplasm is outside the nucleus

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7.2 Eukaryotic Cell Structure
Like a Factory!
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Nucleus
Cell control center
Contains cell's DNA
DNA provides instructions
to make proteins!
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CHROMATIN

• DNA bound to protein in the nucleus

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Nucleolus

• Where ribosomes are made

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Ribosomes

• Are made of RNA and protein
• Assemble proteins
• Protein assembly instruction comes from the
  nucleus
• Cells active in protein synthesis have many
  ribosomes

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Endoplasmic reticulum

• Makes and exports proteins and lipids
• Rough ER makes proteins? ribosomes!
• Smooth ER makes enzymes

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Golgi Apparatus
Modifies, sorts and packages
Customizes proteins made in ER
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Lysosomes

• Clean up crew, remove junk!
• Digest or break down lipids, carbohydrates,
  proteins and old organelles
• Filled with enzymes

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Vacuoles
Provide storage of
and control water content
Take up space!
carbs, H2O, salts, proteins...
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Mitochondria
Powerhouse of the cell!
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• Converts food into compounds the cell uses
• Mitochondria are from the egg cell, so thank
  your MOM!

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Chloroplasts

• Plant cells
• Capture energy from the sun and convert it into
  chemical energy Photosynthesis

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Cytoskeleton

• A network of protein filaments
• Help the cell maintain its shape/structure
• Made of microtubules and microfilaments

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Centrioles

• Help organize cell division

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Cilia Flagella
Move cells
Flagellum
CILIA
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7.3 Cell Boundaries

• All cells are surrounded by a thin, flexible
  membrane
• Plant cells also have a cell wall surrounding the
  membrane

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Cell Membrane

• Regulates what comes in out of the cell
• Provides structure and support
• Made of a lipid bilayer which provides a strong
  flexible barrier

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A membrane mosaic?

• The lipid bilayer has carbs AND proteins embedded
  within!

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Cell Wall

• Located outside cell membrane in plant, algae
  fungi and prokaryotic cells
• Usually made of carbs protein
• Plant cell walls made of cellulose
• Provides protection and support

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DIFFUSION

• When particles move from areas of high
  concentration to areas of low concentration
• Equilibrium occurs when the concentration of
  solute (particles) is the same throughout

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The Dye SoluteWater Solvent
Equilibrium!
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Osmosis

• Water passes easily across membranes
• Osmosis is the diffusion of water across a
  selectively permeable membrane

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Isotonic
Concentration of solute
is equal on both
sides of the membrane
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Hypertonic
Solute concentration
is higher OUTSIDE the cell
so water moves OUT of cell
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Hypotonic
Solute concentration
is higher inside the cell
so water moves into the cell
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Isotonic
Hypertonic
Hypotonic
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Facilitated Diffusion

• Certain molecules can pass through cell membranes
  with help from protein friends

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Active Transport

• Sometimes cells must move materials the opposite
  direction as diffusion
• This requires energy
• Transport proteins or pumps help this happen

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Endocytosis
Membrane never breaks!
Large particles are moved
into the cell by being
wrapped in the plasma membrane
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Exocytosis
Large materials are exported
without crossing the cell membrane
Many are partially digested
lysosomes
by ______________ 1st!
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Let's Review!
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Phagocytosis

• A form of endocytosis
• Means cell eating
• Cell sends out projections called pseudopodia

Click me!
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Pinocytosis

• Means cell drinking
• Usually particles are dissolved in water
• A form of endocytosis