• Has resolution that is sufficient
to view images up to 0.2
micrometers, due to the
limitations of the wavelength of
light.
• Scientists ran in to problems
when they wanted to see
smaller things, such as in Figure
1.
New technology was needed, and
thus came the Electron Microscope
Figure 1. Image from www.cytochemistry.net
• Uses beams of electrons,
rather than light, so a much
clearer resolution can be
achieved.
• Useful to view images down to
1 nm (0.001 micrometers)
• Useful to see images such as
those of viruses and small
organelles.
Prokaryotes
• Prokaryotes are cells that have
no membrane-bound organelles
• Smaller than animal or plant
cells
• Very Old! ~3.5 billion years old
• One BIG
compartment
Vs.
• Cell wall – provides structure, protection for the cell
• Cell membrane – provides shape, allows materials in and out of
the cell (selectively permeable)
• Pili – allow attachment to other bacteria in order to share DNA
• Ribosomes – synthesize proteins for the cell
• Nucleoid – region containing DNA, instructions for cell processes
• Cytoplasm – space in which metabolic reactions can take place
• Flagella – utilize whip-like motion to move the cell
• Prokaryotes use a method of
asexual reproduction termed
Binary Fission.
• Binary fission allows prokaryotes to
divide in to two identical bacterium
Eukaryotes
Size
DNA
Nucleus
Organelle
Ribosomes Mitochondr
ia
Prokaryote
1-3
micrometer
Closed
loop
DNA in
cytoplasm
“cell parts”
70S (small)
No
Eukaryotes
10-100
micrometer
Double
helix
Has nuclear Membrane
membrane bound
80S (big)
yes
• Draw overall structure
and label the
following based on
the diagram:
•
•
•
•
•
•
•
•
•
Golgi Apparatus
Lysosome
Mitochondrion
Free Ribosomes
Chloroplast
Vacuoles
Microtubules
Centrioles
Cilia/flagella (not
pictured)
• Rough ER
• Nucleus
vs.
• Eukaryotic cells are compartmentalized
• Advantages of being so include:
• Enzymes and substrates for a particular process can be much more
concentrated than if they were spread out
• Potentially harmful substances can be quarantined
• pH and other homeostatic levels can be managed much more effectively
• Organelles with their contents can be moved around within the cell
• Nucleus – contains chromosomes, which are organized raw DNA
• Most of the time, they are visible as chromatin, an unorganized form of
DNA
• Consists of flattened sacs –
cisternae
• Ribosomes attach to them,
and fulfill protein synthesis
• Consists of flattened membrane sacs called cisternae, similar to
the rough ER
• These cisternae are shorter, have no ribosomes attached, and
have many vesicles nearby
• Golgi Apparatus processes proteins brought to it from the rER
• Little spherical organelles,
formed out of golgi vesicles
• Have a high concentration of
protein, mostly digestive
enzymes that they use to break
down food particles
• Also responsible for breaking
down “old” organelles and
intruders, such as bacteria
• Double membrane! – inner membrane is invaginated (folded
inwards) to form structures called cristae
• Produce ATP (energy for the cell) by aerobic respiration
• No membrane! – same size as ribosomes attached to the rER,
only 20 nm in length
• Synthesize proteins for the cell and its surroundings
• Produced in the nucleolus
• Only found in photosynthetic cells
• Double membrane! – performs photosynthesis
• Photosynthesis produces a wide variety of compounds, including glucose
• Vacuoles vary widely in size –
• Very small in animals (generally)
• Very large in plants (generally)
• Used for a variety of purposes,
including digestion, water balance,
transport
• What do you think the function of
this palisade mesophyll cell is?
• Small, cylindrical fibers called microtubules that provide
structure to the cell
• Centrioles are present in animal cells, and provide an anchoring
point for microtubules during mitosis
• Whip-like structures that allow the cell to move
• Comprised of a ring of double microtubules and two central
ones
• While cilia and flagella can both be used for locomotion, cilia
can also be used to create a current next to the cell
• What do you think these
structures indicate about the
cell’s function in Figure 1? SOC
Figure 1.
What about the cell in Figure 2?
SOC
Figure 2.
• Eukaryotic, and therefore
have all the characteristics
of a eukaryotic cell
• In addition to the
organelles present in
animal cells, plant cells
also have chloroplast, a
cell wall, and an enlarged
vacuole.
plant
SOC