Microbiology

Cells

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Prokaryotes vs Eukaryotes

• Examples of Prokaryotes:– Bacteria– Cyanobacteria– Archaebacteria

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Bacteria (Anthrax)

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Cyanobacteria

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Archaebacteria

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Prokaryotes vs Eukaryotes

• Examples of Eukaryotes:– Plant cells– Animal cells– Fungal cells– Protozoan cells

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Plant Cell

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Animal Cell (Liver)

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Fungal Cell (Yeast)

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Protist Cell (Paramecium)

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Prokaryotes vs Eukaryotes

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Prokaryotes vs EukaryotesSimilarities

• Both contain DNA as genetic material

• Both contain ribosomes

• Both contain RNA

• Both respire and produce proteins

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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

Eukaryotic Cellular Organization

Cell Structures and Organelles

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Eukaryotic Cell

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Plasma Membrane

• Phospholipid bilayer

• Selectively permeable

• Proteins– Channel proteins

– Receptor proteins

– Antigens-glycoproteins

• Sterols- add rigidity– Cholesterol

– Ergosterol

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Cell Membrane (cont.)

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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

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Nucleus (cont.)

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Nucleus (cont.)

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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

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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

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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

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Mitochondrian

• Surrounded by an outer membrane

• Inner membrane is folded- Cristae

• Matrix-semifluid contents of inner membrane

• Powerhouse of the cell

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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

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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

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Chloroplast (cont.)

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Vacuoles

• Store starch, glycogen, or fat to be used for energy

• Store water in plant cells- usually larger in size

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Lysosomes

• Primarily found in animal cells

• Contain hydrolytic enzymes for digestion

• Sometimes called “suicide sacs”

• Produced by the golgi bodies

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Cytoskeleton

• Protein fibers- microtubules and microfilaments

• Supports the cell• Provides rigidity and

shape to the cell• Assists in movement-

ameboid movement of wbc’s

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Cell Wall

• Found in plants, fungi, and some algae

• Functions:– Supports the cell– Prevents from lysis due to osmotic pressure

• Main structural component- cellulose

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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

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Cilia and Flagellastuctures of movement

• Cilia– Structure similar to flagella– Shorter- and more numerous than flagella– Found in some animal cells, and protozoans

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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

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Plant vs Animal