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2Microbiology: Cells04/18/23
Prokaryotes vs Eukaryotes
• Examples of Prokaryotes:– Bacteria– Cyanobacteria– Archaebacteria
6Microbiology: Cells04/18/23
Prokaryotes vs Eukaryotes
• Examples of Eukaryotes:– Plant cells– Animal cells– Fungal cells– Protozoan cells
12Microbiology: Cells04/18/23
Prokaryotes vs EukaryotesSimilarities
• Both contain DNA as genetic material
• Both contain ribosomes
• Both contain RNA
• Both respire and produce proteins
13Microbiology: Cells04/18/23
Prokaryotes vs EukaryotesDifferences
Prokaryotes• No true nucleus • No membrane bound
organelles• No cytoplasmic streaming• Single, circular
chromosome• Plasmids present• Cells smaller in size• Ribosomes are smaller• Cell wall - peptidoglycan
Eukaryotes• Contain a true nucleus• Contain membrane bound
organelles• Cytoplasm streams• Minimum of 2 linear
chromosomes• No plasmids• Cells larger in size• Ribosomes are larger• Cell wall- cellulose
04/18/23 Microbiology: Cells 16
Plasma Membrane
• Phospholipid bilayer
• Selectively permeable
• Proteins– Channel proteins
– Receptor proteins
– Antigens-glycoproteins
• Sterols- add rigidity– Cholesterol
– Ergosterol
04/18/23 Microbiology: Cells 18
Nucleus
• Nuclear Envelope– Composed of a double
membrane– Contains pores allowing
RNA to pass
• Nucleolus– Produces ribosomal RNA-
subunits of ribosomes
• Chromatin– Active form of
chromosomes– Composed of DNA and
histones
04/18/23 Microbiology: Cells 21
Endoplasmic Reticulum
• Two types- rough and smooth
• Transport system in the cell
• Rough ER- contain ribosomes-assists in the production and transport of proteins
• Smooth ER-involved in production of lipids-especially for the membrane
04/18/23 Microbiology: Cells 22
Ribosomes
• Attach to endoplasmic reticulum or are free in the cytoplasm
• Produce proteins – Attached- produce
proteins to be shipped out of the cell
– Free- produce proteins to be used by the cell
• 80s in size
04/18/23 Microbiology: Cells 23
Golgi Apparatus
• Golgi bodies-individual units
• Golgi apparatus-network of golgi bodies
• Stacks of flattened membrane sacs
• Receive substances from the ER
• Packages substances to be sent out in vesicles
• Assist in producing membrane and lysosomes
04/18/23 Microbiology: Cells 24
Mitochondrian
• Surrounded by an outer membrane
• Inner membrane is folded- Cristae
• Matrix-semifluid contents of inner membrane
• Powerhouse of the cell
04/18/23 Microbiology: Cells 25
Mitochondrian (cont.)
• Site of aerobic respiration in the eukaryotic cell
• Contain their own ribosomes- 70s in size
• Contain a single chromosome
• Capable of reproducing on their own
• Endosymbiont theory
04/18/23 Microbiology: Cells 26
Chloroplasts
• Composed of two membranes like mitochondria
• Thylakoids-flattened disks that contain chlorophyll
• Stacks of thylakoids-grana• Site of photosynthesis• Contain their own
ribosomes- 70s in size• Contain a single
chromosome
30Microbiology: Cells04/18/23
Vacuoles
• Store starch, glycogen, or fat to be used for energy
• Store water in plant cells- usually larger in size
04/18/23 Microbiology: Cells 31
Lysosomes
• Primarily found in animal cells
• Contain hydrolytic enzymes for digestion
• Sometimes called “suicide sacs”
• Produced by the golgi bodies
04/18/23 Microbiology: Cells 32
Cytoskeleton
• Protein fibers- microtubules and microfilaments
• Supports the cell• Provides rigidity and
shape to the cell• Assists in movement-
ameboid movement of wbc’s
33Microbiology: Cells04/18/23
Cell Wall
• Found in plants, fungi, and some algae
• Functions:– Supports the cell– Prevents from lysis due to osmotic pressure
• Main structural component- cellulose
04/18/23 Microbiology: Cells 34
Cilia and Flagellastructures of movement
• Flagella– 2 microtubules surrounded
by 9 pair of microtubules
– Whip to propel
– Microtubules slide toward or away from base of cell
– Found in sperm cells,
some protozoa and some algae
35Microbiology: Cells04/18/23
Cilia and Flagellastuctures of movement
• Cilia– Structure similar to flagella– Shorter- and more numerous than flagella– Found in some animal cells, and protozoans
36Microbiology: Cells04/18/23
Plants vs Animals
Plants• Contain a cell wall• Contain chloroplasts• Large central vacuole• No centrioles
Animals• No cell wall• No chloroplasts• Some have vacuoles
but usually smaller• Contain centrioles-
structures used in reproduction