CHAPTER 6 A TOUR OF THE CELL

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CHAPTER 6A TOUR OF THE CELL
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Cytology science/study of cells

• Light microscopy resolving power measure of
  clarity
• Electron microscopy
• TEM electron beam to study cell
  ultrastructure
• SEM electron beam to study cell
  surfaces
• Cell fractionation cell separation organelle
  study
• Ultracentrifuge cell fractionation 130,000rpm

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A cell is a living unit greater than the sum of
its parts

• While the cell has many structures that have
  specific functions, they must work together.

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Types of cells
Prokaryotebacteria cells
- no organelles
- organelles
Eukaryoteanimal cells
Eukaryoteplant cells
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Cell Types Prokaryotic

• Nucleoid DNA
• concentration
• No organelles with
• membranes
• Ribosomesprotein synthesis
• Plasma membrane (all
• cells) semi-permeable
• Cytoplasm/cytosol(all cells)

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Cell types Eukaryotic

• Nucleusmembrane enclosed organelle containing
  chromosomes
• Membrane bound organelles of specialized form and
  function
• Generally larger than prokaryotic cells

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Cell Size

• As cell size increases, the surface area to
  volume ratio decreases
• Rates of chemical exchange may then be inadequate
  for cell size
• Cell size, therefore, remains small

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Why organelles?

• Specialized structures
• specialized functions
• cilia or flagella for locomotion
• Containers
• partition cell into compartments
• create different local environments
• separate pH, or concentration of materials
• distinct incompatible functions
• lysosome its digestive enzymes
• Membranes as sites for chemical reactions
• unique combinations of lipids proteins
• embedded enzymes reaction centers
• chloroplasts mitochondria

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Cells gotta work to live!

• What jobs do cells have to do?
• make proteins
• proteins control every cell function
• make energy
• for daily life
• for growth
• make more cells
• growth
• repair
• renewal

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Proteins do all the work!
proteins
cells
DNA
Repeat after me Proteins do all the work!
organism
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Cells functions

• Building proteins
• read DNA instructions
• build proteins
• process proteins
• folding
• modifying
• removing amino acids
• adding other molecules
• e.g, making glycoproteinsfor cell membrane
• address transport proteins

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Building Proteins

• Organelles involved
• nucleus
• ribosomes
• endoplasmic reticulum (ER)
• Golgi apparatus
• vesicles

nucleus
vesicles
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Nucleus

• Function
• protects DNA
• Structure
• nuclear envelope
• double membrane
• membrane fused in spots to create pores
• allows large macromolecules to pass through

What kind of molecules need to pass through?
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Nucleolus

• Function
• ribosome production
• build ribosome subunits from rRNA proteins
• exit through nuclear pores to cytoplasm
  combine to form functional ribosomes

rRNA proteins
nucleolus
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Ribosomes

• Function
• protein production
• Structure
• rRNA protein
• 2 subunits combine

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Types of Ribosomes

• Free ribosomes
• suspended in cytosol
• synthesize proteins that function in cytosol
• Bound ribosomes
• attached to endoplasmic reticulum
• synthesize proteins for export or for membranes

membrane proteins
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Endoplasmic Reticulum

• Function
• processes proteins
• manufactures membranes
• synthesis hydrolysis of many compounds
• Structure
• membrane connected to nuclear envelope extends
  throughout cell

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Types of ER
rough
smooth
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Smooth ER function

• Membrane production
• Many metabolic processes
• synthesis
• synthesize lipids
• oils, phospholipids, steroids sex hormones
• hydrolysis
• hydrolyze glycogen into glucose
• in liver
• detoxify drugs poisons
• in liver
• ex. alcohol barbiturates

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Membrane Factory

• Build new membrane
• synthesize phospholipids
• builds membranes
• ER membrane expands
• bud off transfer to other parts of cell that
  need membranes

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Rough ER function

• Produce proteins for export out of cell
• protein secreting cells
• packaged into transport vesicles for export

Which cellshave lot of rough ER?
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Golgi Apparatus
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Vesicle transport
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Any Questions!!