Chapter 6 – Tour of the Cell
Microscopy:
○ Light microscopy vs. electron microscopy:
LIGHT MICROSCOPY (LM): uses visible light to illuminate samples
- Uses a magnification up to 1000x with a typical resolution around 0.2 micrometers
- Best for observing larger structures (cell membranes, nuclei, some organelles)
- TYPES OF LIGHT MICROSCOPY:
- Bright-field
- Phase contrast
- Fluorescence
ELECTRON MICROSCOPY (EM): Uses electron beams instead of light- providing much higher
resolution
- Transmission Electron Microscopy (TEM): Provides internal structure details of
cells and organelles with a magnification up to 10 million times
- Scanning Electron Microscopy (SEM): Provides 3D surface details of specimens,
best for observing small organelles
○ Best techniques for observing small organelles like ribosomes:
Electron Microscopy, specifically TEM - because it provides the highest magnification and
resolution
- Ribosomes are small (25-35 nm), making light microscopy unsuitable for their
visualization
Cell Types:
○ Prokaryotic vs. Eukaryotic:
PROKARYOTIC: Smaller in size (1-10 micrometers), NO membrane bound nucleus
- Organelles: NO membrane bound organelles - contain structures like ribosomes,
plasma membrane, and a nucleiod region (where the DNA is found)
- Ex: Bacteria and Archaea
EUKARYOTIC: Larger in size (10-100 micrometers), HAS a membrane bound nucleus
(containing DNA)
- Organelles: HAVE membrane bound organelles like the nucleus, mitochondria,
endoplasmic reticulum, golgi apparatus, etc.
- Ex: Plants, Protists, Fungi, and Animals
, ○ Organelles unique to plant, animal, and bacterial cells:
Plant Cells:
- Cell wall: Made of cellulose
- Chloroplasts: For photosynthesis
- Central Vacuole: Large, used for storage and maintaining turgor pressure
Animal Cells:
- Lysosomes: Contain digestive enzymes
- Centrioles: Involved in division
Bacterial Cells:
- Cell Wall: Made of peptidoglycan
- Plasmids: Small DNA molecules
- Flagella: For movement
- Pili: For attachment and genetic transfer
Cell Organelles & Functions:
○ Nucleus, nuclear pore complex:
NUCLEUS: The control center of the cell, containing the DNA. Surrounded by a double
membrane nuclear envelope
NUCLEAR PORE COMPLEX: A large complex of proteins that regulates the transport of
molecules (RNA, Ribosomes) between the nucleus and the cytoplasm.
- Controls the entry and exit of materials
○ Smooth & rough ER:
ROUGH ER: Studded with ribosomes and is the site of protein synthesis and modification
- Newly synthesized proteins are transported to the golgi or the cell membrane
SMOOTH ER: Lacks ribosomes, site of lipid synthesis, detoxification, and calcium storage
- In liver cells, it detoxifies harmful drugs, toxins, and ethanols
○ Golgi apparatus:
Modification, sorting, and packaging of proteins and lipids received from the ER
- Vesicles containing modified molecules are sent to their respective destinations
(plasma membrane, lysosomes, etc)
- Cis Face Golgi: RECEIVING SIDE
- Trans Face Golgi: EXITING SIDE
, ○ Mitochondria:
Powerhouse of the cell, site of ATP production through cellular respiration
- Contains its own DNA and ribosomes
- Endosymbiotic Theory: Explains how mitochondria and chloroplasts evolved from
prokaryotic cells, the theory suggest that prokaryotes were engulfed by larger cells
and became symbiotic partners
○ Ribosomes:
Site of protein synthesis, and are composed of rRNA and small proteins
- Can be free-floating in the cytoplasm or attached to the rough ER
○ Lysosomes:
Contain hydrolytic enzymes (digestive enzymes) that break down wates, cellular debris, and
foreign substances
- Autophagy: the breakdown of damaged organelles to be recycled, and phagocytosis
- Autolysis: the destruction of a cell (bursts open) throught the action of its own
enzymes. AKA self-digestion
○ Vacuoles:
Storage vesicles in the cell
- Plant vacuoles: are large, central, and store water, ions, and nutrients. They also
help maintain turgor pressure
- Animal vacuoles: are smaller, and are involved in processes like phagocytosis.
Cytoskeleton: A structural network of protein filaments that give the cell shape and enable
movement
○ Microtubules (tubulin):
The largest protein filament of the cytoskeleton
- Hollow tubes made of alpha and beta tubulin
- Involved in cell division (spindle formationa) and intracellular transport (moving
organelles and vesicles)
- Form the core of cilia and flagella
○ Microfilaments (actin):
The smallest protein filament of the cytoskeleton
- Made of actin filaments
- Involved in cell movement (muscle contraction, amoeboid movement) and cell shape
Microscopy:
○ Light microscopy vs. electron microscopy:
LIGHT MICROSCOPY (LM): uses visible light to illuminate samples
- Uses a magnification up to 1000x with a typical resolution around 0.2 micrometers
- Best for observing larger structures (cell membranes, nuclei, some organelles)
- TYPES OF LIGHT MICROSCOPY:
- Bright-field
- Phase contrast
- Fluorescence
ELECTRON MICROSCOPY (EM): Uses electron beams instead of light- providing much higher
resolution
- Transmission Electron Microscopy (TEM): Provides internal structure details of
cells and organelles with a magnification up to 10 million times
- Scanning Electron Microscopy (SEM): Provides 3D surface details of specimens,
best for observing small organelles
○ Best techniques for observing small organelles like ribosomes:
Electron Microscopy, specifically TEM - because it provides the highest magnification and
resolution
- Ribosomes are small (25-35 nm), making light microscopy unsuitable for their
visualization
Cell Types:
○ Prokaryotic vs. Eukaryotic:
PROKARYOTIC: Smaller in size (1-10 micrometers), NO membrane bound nucleus
- Organelles: NO membrane bound organelles - contain structures like ribosomes,
plasma membrane, and a nucleiod region (where the DNA is found)
- Ex: Bacteria and Archaea
EUKARYOTIC: Larger in size (10-100 micrometers), HAS a membrane bound nucleus
(containing DNA)
- Organelles: HAVE membrane bound organelles like the nucleus, mitochondria,
endoplasmic reticulum, golgi apparatus, etc.
- Ex: Plants, Protists, Fungi, and Animals
, ○ Organelles unique to plant, animal, and bacterial cells:
Plant Cells:
- Cell wall: Made of cellulose
- Chloroplasts: For photosynthesis
- Central Vacuole: Large, used for storage and maintaining turgor pressure
Animal Cells:
- Lysosomes: Contain digestive enzymes
- Centrioles: Involved in division
Bacterial Cells:
- Cell Wall: Made of peptidoglycan
- Plasmids: Small DNA molecules
- Flagella: For movement
- Pili: For attachment and genetic transfer
Cell Organelles & Functions:
○ Nucleus, nuclear pore complex:
NUCLEUS: The control center of the cell, containing the DNA. Surrounded by a double
membrane nuclear envelope
NUCLEAR PORE COMPLEX: A large complex of proteins that regulates the transport of
molecules (RNA, Ribosomes) between the nucleus and the cytoplasm.
- Controls the entry and exit of materials
○ Smooth & rough ER:
ROUGH ER: Studded with ribosomes and is the site of protein synthesis and modification
- Newly synthesized proteins are transported to the golgi or the cell membrane
SMOOTH ER: Lacks ribosomes, site of lipid synthesis, detoxification, and calcium storage
- In liver cells, it detoxifies harmful drugs, toxins, and ethanols
○ Golgi apparatus:
Modification, sorting, and packaging of proteins and lipids received from the ER
- Vesicles containing modified molecules are sent to their respective destinations
(plasma membrane, lysosomes, etc)
- Cis Face Golgi: RECEIVING SIDE
- Trans Face Golgi: EXITING SIDE
, ○ Mitochondria:
Powerhouse of the cell, site of ATP production through cellular respiration
- Contains its own DNA and ribosomes
- Endosymbiotic Theory: Explains how mitochondria and chloroplasts evolved from
prokaryotic cells, the theory suggest that prokaryotes were engulfed by larger cells
and became symbiotic partners
○ Ribosomes:
Site of protein synthesis, and are composed of rRNA and small proteins
- Can be free-floating in the cytoplasm or attached to the rough ER
○ Lysosomes:
Contain hydrolytic enzymes (digestive enzymes) that break down wates, cellular debris, and
foreign substances
- Autophagy: the breakdown of damaged organelles to be recycled, and phagocytosis
- Autolysis: the destruction of a cell (bursts open) throught the action of its own
enzymes. AKA self-digestion
○ Vacuoles:
Storage vesicles in the cell
- Plant vacuoles: are large, central, and store water, ions, and nutrients. They also
help maintain turgor pressure
- Animal vacuoles: are smaller, and are involved in processes like phagocytosis.
Cytoskeleton: A structural network of protein filaments that give the cell shape and enable
movement
○ Microtubules (tubulin):
The largest protein filament of the cytoskeleton
- Hollow tubes made of alpha and beta tubulin
- Involved in cell division (spindle formationa) and intracellular transport (moving
organelles and vesicles)
- Form the core of cilia and flagella
○ Microfilaments (actin):
The smallest protein filament of the cytoskeleton
- Made of actin filaments
- Involved in cell movement (muscle contraction, amoeboid movement) and cell shape
