09/29/09

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What do ALL need to to carry out life processes?

Are all the ?

Are ALL living organisms made of ?

What is a

I. Types of Cells: General CharacteristicsA. Bacterial Cells B. Archaeal CellsC. Eukaryal Cells

II. Cell StructuresA. Plasma Membrane

1. Bacterial and Eukaryal Plasma Membrane Structure2. Archaeal Plasma Membrane Structure3. Functions of the Plasma Membrane

B. Cell Wall1. Bacterial Cell Walls2. Archaeal Cell Walls3. Eukaryal Cell Walls

C. Structures External to the Cell Wall1. Glycocalyx2. Movement Appendages 3. Attachment Appendages4. Cell Surface Molecules5. Bacteria only! DNA Exchange Appendages

D. Structures Internal to the Plasma Membrane1. Structures Common to both Prokaryotic and Eukaryotic Cells

a. Cytoplasmb. Genetic Material- DNA

1) Chromosomes2) Plasmids3) ‘Nucleus’

c. Ribosomesd. Inclusions

2. Bacteria only! Endospores3. Eukaryotes only! Complexity, Compartmentalization, INTERNAL MEMBRANES

a. Cytoskeletonb. Chloroplastsc. Mitochondriad. ER and Golgi Complexe. Lysosomes and Peroxisomesf. Vesicles and Vacuoles

III. Progression from Prokaryotic Cells to Eukaryotic Cells

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Draw as you go: Cells

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Prokaryotic: Bacteria and Archaea

Eukaryotic: protozoans, unicellular algae, molds, yeast

I. Three Primary Types of Cells

1http://en.wikipedia.org/wiki/Bacteria2http://en.wikipedia.org/wiki/Archaea3http://en.wikipedia.org/wiki/Eukaryote

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Bacteria1

Gram Positive, Spirochaetes, Purple bacteria (Proteobacteria), Cyanobacteria, Flavobacteria/Bacteroides, Green Sulfur Bacteria, Green Nonsulfur Bacteria, Thermatogales

Archaea2

2-5 groups tentatively identified, but include the following: Methane-producers, Extreme Halophiles, Thermoacidophiles

Eukarya3

Plants, Animals, Fungi (molds and yeast), and Protists (algae, protozoans, slime molds, etc.)

A. Bacterial Cells 1. Size: Most bacteria range from 0.2 micrometer to 2.0 micrometers in diameter

and 2-8 micrometers in length

2. Shapes and Arrangements TEXT Fig. 4.1

a. Cocci

http://student.ccbcmd.edu/courses/bio141/lecguide/unit1/shape/u1coccus.html

Streptococcus pneumoniae(diplococcus)

-Cocci: More resistant to drying than rods.

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b. Bacilli TEXT Fig. 4.2 & 4.6

http://student.ccbcmd.edu/courses/bio141/lecguide/unit1/shape/rod.html

-Rods: Increased surface area, so can more easily take in dilute nutrients from the environment.

Bacterial cells

Some structures discussed in the lecture guide are not listed on this diagram: glycocalyx slime layer, axial filaments, endospore

Single rods

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c. Curved TEXT Fig. 4.4

1) Spirochetes: Both syphilis and Lyme disease are caused by these bacteria, and other species are important symbionts in the stomachs of cows and other ruminants. They are very thin, flexible, spiral-shaped bacteria that move by means of structures called axial filaments.

2) Spirilla have a helical or spiral shape. Unlike spirochetes, they have a rigid cell wall and are motile by means of ordinary polar flagella.

-Spiral: Corkscrew motion & therefore less resistant to movement.

3) Vibrio: The name Vibrio derives from the Latin because these curved rods possess a single polar flagellum and appear "to vibrate". They are often implicated in foodborne diseases.

V. cholerae. Gastrointestinal symptoms and the presense of a rice water stool are presumptive for cholera. Direct examination of the feces may indicate vibrios.

V. vulnificus. Persons who are immunocompromised, especially those with chronic liver disease, are at risk for V. vulnificus when they eat raw seafood, particularly oysters. A recent study showed that people with these pre-existing medical conditions were 80 times more likely to develop V. vulnificus bloodstream infections than were healthy people. The bacterium is frequently isolated from oysters and other shellfish in warm coastal waters during the summer months. Since it is naturally found in warm marine waters, people with open wounds can be exposed to V. vulnificus through direct contact with seawater. There is no evidence for person-to-person transmission of V. vulnificus.

Most spirochetes are free living (in muds and sediments), or live in associations with animals (e.g. in the oral cavity or GI tract). A few are pathogens of animals (e.g. leptospirosis in dogs, Syphilis in humans and Lyme Disease in dogs and humans).

Self-reading: Two pathogens of humans are found among the spirilla. Campylobacter jejuni is an important cause of bacterial diarrhea, especially in children. The bacterium is transmitted via contaminated food, usually undercooked poultry or shellfish, or untreated drinking water. Helicobacter pylori is able to colonize the gastric mucosal cells of humans, i.e., the lining of the stomach, and it has been fairly well established as the cause of peptic ulcers.

There are exceptions to the usual bacterial shapes: some examples are Trichome (also referred to as palliside or picket-fences), sheathed, stalked, filamentous, square, star-shaped, spindle-shaped, lobed, and pleomorphic (def).

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B. Archaeal Cells TEXT Fig. 4.5b

1. Very small, usually less than 1 micron.

2. Variety of shapes: coccus (regular spheres, lobed, lumpy), bacillus, spiral, or other (triangular, square)

Basic Archaeal Shapes : At far left, Methanococcus janaschii, a coccus form with numerous flagella attached to one side. At left center, Methanosarcina barkeri, a lobed coccus form lacking flagella. At right center, Methanothermus fervidus, a short bacillus form without flagella. At far right, Methanobacterium thermoautotrophicum, an elongate bacillus form.

http://www.ucmp.berkeley.edu/archaea/archaeamm.html

-Square shapes help cope with high salinity environments.

Archaea include some truly weird microbes that thrive in extremely salty water, as well as microbes that live in temperatures of hundreds of degrees. Even more recently, scientists have begun finding archael cells in an increasing array of habitats, such as the ocean surface, deep ocean muds, salt marshes, the guts of animals, and even in oil reserves deep below the surface of the Earth. Archaea have gone from obscurity to being nearly ubiquitous in only 25 years!http://www.ucmp.berkeley.edu/archaea/archaeasy.html

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C. Eukaryal Cells

1. Eukaryotic cells are generally larger and much more complex than prokaryotic cells. 2. Many different shapes and sizes.

mitochondrion

Endoplasmic reticulum

vacuole

cytoskeleton

plasma membrane

nucleus

Golgi complex

lysosomes

vesicle

peroxisomes

Ribosomes (on ER)

centriole

cytoplasm

Yeast (Candida albicans)http://www.cat.cc.md.us/courses/bio141/lecguide/unit1/proeu/u1fig2.html

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Eukaryotic Animal/Plant CellTEXT Fig. 4.22 a p. 99

Comparing sizes: Animation comparing viruses, bacteria, eukaryotic cells http://www.cellsalive.com/howbig.htm

Eukaryotic cells are highly compartmentalized. A large surface-to-volume ratio, as seen in smaller prokaryotic cells, means that nutrients can easily and rapidly reach any part of the cells interior. However, in the larger eukaryotic cell, the limited surface area when compared to its volume means nutrients cannot rapidly diffuse to all interior parts of the cell. That is why eukaryotic cells require a variety of specialized internal organelles to carry out metabolism, provide energy, and transport chemicals throughout the cell (most of the things needed for a particular function are kept together).

TEXT Table 4.2 p. 101 Principle Differences between Prokaryotic and Eukaryotic Cells

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II. Cell Structures

Structure Lecture Guide page(s)

Bacteria Archaea Eukaryota

General infoPlasma MembraneCell WallGlycocalyxMovement AppendagesAttachment Appendages Cell Surface MoleculesDNA Exchange AppendagesGenetic Material-DNARibosomesInclusionsEndosporesCytoskeleton ChloroplastsMitochondria ER & Golgi BodyLysosomes & PeroxisomesVesicles & VacuolesCentrioles

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A. Plasma Membrane

1. Bacterial and Eukaryal Plasma Membrane Structure

Inverted phospholipid bilayer containing proteins

Phospholipid

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TEXT Fig. 4.14

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2. Archaeal Plasma Membrane Structure

Archaeal cell membranes are chemically different from all other living things.

a. Glycerol component (found with the phosphate in the ‘head’) is a ‘mirror image’ (stereoisomer) of bacterial and eukaryal cell membrane glycerol.

b. Linkage (type of bond) between the glycerol and side chains (‘tails’) is different. This results in different properties.

c. Side chains are not fatty acids in Archaea. Isoprenes1 are common.

1 Isoprenes are a large and diverse group of lipids (they are not fatty acids) http://www.cem.msu.edu/~reusch/VirtualText/lipids.htm

Archaea

Bacterial, Eukaryal

Sidechains

Notice branching

No branching

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Here is the situation. You are hungry. You haven’t eaten for days. You find a large piece of bread. It is too large to fit in your mouth. What do you do? How did you accomplish this?

3. Functions of the plasma membrane:

a. Regulation of the movement of materials into and out of the cell; the plasma membrane is SEMIPERMEABLE (selectively permeable)

1) How do molecules move across the plasma membrane?

a) Diffusion

Simple (passive)

o Special example: osmosis

Facilitated

b) Active transport

c) Group translocation

d) Cytosis

TEXT Fig. 4. 17-4.18: Facilitated diffusion and osmosis

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a) Diffusion: (def.)

Concentration:

# of particles of a specific substance/total # of all particles of all substances

Gradient:

Difference in the concentration of a substance in one area compared to an adjacent area

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Simple (Passive) Diffusion

-No energy is used.-Transmembrane protein channels may be required.

Osmosis: TEXT Fig. 4.18 p. 93Movement of water across a membrane by simple diffusion in response to the concentration of molecules that cannot cross the membrane (impermeable).

-Water is a solvent (dissolver) for many molecules (solutes; for example salts and sugars).

Note: The solution refers to the surrounding environmental solution outside of the cell.

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1) Isotonic solution: If solute concentration outside of the cell is the same as that inside, the solution is isotonic.

2) Hypotonic solution: a solution with a lower solute concentration than that inside the cell is hypotonic.

3) Hypertonic solution: a solution with a higher solute concentration than that inside the cell is hypertonic.

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Facilitated Diffusion

-Movement WITH (along) the concentration gradient.

-No energy is used.

-Transmembrane ‘trasnporter/porin’ proteins are required.

b) Active Transport

-Movement AGAINST the concentration gradient.

-Energy is required.

-Transporter protein(s) are required.

c) Group Translocation

-Only occurs in prokaryotes, not eukaryotes.

Transported substance is chemically altered during passage through the membrane.

Examples: Carbohydrates, fatty acids, some nucleic acid building blocks.

In E. coli, glucose outside the cell is phosphorylated during transport into the cell.

-Energy is utilized.

-Enzymes are required.

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d) Cytosis

Eukaryotic cells do not undergo group translocation.

-On the other hand, eukaryotic cells undergo transport systems that prokaryotes do not: Cytosis

A transport process in which 1) a substance is engulfed by the cytoplasmic membrane to form a vesicle inside the cell containing the substance or 2) when a vesicle already in the cell fuses with the plasma membrane releasing the contents of the vesicle out of the cell.

o Endocytosis- movement into the cell

o Exocytosic- movement out of the cell

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b. Proteins (enzymes) catalyze reactions involved in...

1) Nutrient breakdown

2) Molecule secretion

3) Environmental monitoring/Cell communication (signaling)

4) Cell wall synthesis

Bacteria and Archaea only:

5) Respiration and fermentation (reactions to acquire usable energy)

6) Photosynthesis

7) Chemosynthesis (utilizing inorganic chemicals as an E source)

Functions of the Plasma Membrane

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B. Cell Wall TEXT: Fig. 4.13 p. 86

1. Bacterial Cell Walls: All the members of domain Bacteria, with the exception of four genera (Mycoplasma, Ureaplasma, Spiroplasma, and Anaeroplasma) contain cell walls.

For almost all bacterial species, if it has a cell wall, it contains peptidoglycan.

a. Examples of functions:

1) Prevents the cell from bursting (lysis).

2) Maintains shape.

3) Protection from the environment.However, the cell wall is not a regulatory structure like the cell membrane. Although it is porous, it is not selectively permeable and will let anything pass that can fit through its gaps.

b. Bacterial Cell Wall Components:

All bacterial cell walls contain a compound called peptidoglycan2.

Peptidoglycan is composed of a glycan (sugar) component and a peptide (bonded amino acids) component:

1. Glycan (sugar, carbohydrate) component: 2 monosaccharides

1) NAG (N-acetylglucosamine) 2) NAMA (or NAM; N-acetylmuramic acid)

There is an alternating sequence of NAG and NAMA.

2. Peptide component: Each NAG-NAM layer is connected, or crosslinked, to the other by a ‘bridge’ made of amino acids. The particular amino acids vary among different species. The crosslinked peptidoglycan molecules form a network which covers the cell like a grid.

2 Bacteria without cell walls do not contain peptidoglycan.

Bacterial Cell Walls

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Peptidoglycan can be thought of as a strong, woven mesh that holds the cell shape and prevents it from bursting. It is not a barrier to small molecules, the openings in the mesh are large and all types of molecules can pass through them.

TEXT Fig. 4.13 p. 86

Gram positive vs. Gram negative

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c. Gram positive cell walls

A distinguishing factor among Gram-positive bacteria is that roughly 90% of their cell wall is comprised of peptidoglycan, and a Gram-positve bacteria can have more than 20 layers of peptidoglycan stacked together to form the cell wall (comprising ~50% of the weight of the entire cell). Examples of common Gram-positive cells are Staphylococcus aureus and Streptococcus cremoris, a bacterium used in dairy production.

Another chemical in the G+ cell wall is teichoic acid. Teichoic acid is covalently bonded to NAMA and links various layers of the peptidoglycan mesh together.

Bacterial Cell Walls

Self-reading: The cell wall is the site of action of many important antibiotics and antibacterial agents. Penicillin inhibits cells wall synthesis. Lysozyme an enzyme found in tears and saliva-attacks peptidoglycan. It hydrolyzes the NAG - NAMA linkage.

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d. Gram negative cell walls

Gram negative cell walls have a more complicated structure; but it is comprised of only 20% peptidoglycan. Outside of the plasma (cytoplasmic) membrane is an open area called the periplasmic space. Beyond this is a thin layer of peptidoglycan. External to the peptidoglycan is an additional membrane, the outer membrane (OM).

-Electron micrograph of a Gram negative cell wall.

OM is beneficial to the bacterium. The outer membrane is beneficial to the bacterial cell because it may be able to restrict substances which may damage or prevent the synthesis of peptidoglycan (for example, certain antibiotics).

OM is bad for us. The OM is similar to the inner, cell membrane, but it also contains lipopolysaccharides (LPS-endotoxins). Many species of Gram- bacteria are pathogenic usually due to these lipopolysaccharides. The Black Plague which wiped out a third of the population of Europe was caused by the tiny G- rod, Yersinia pestis. Many enteric (intestinal/bowel related) illnesses can also be attributed to this group of bacteria, such as Salmonella food poisoning. h ttp://medic.med.uth.tmc.edu/path/00001443.htm

Bacterial Cell Walls

(OM)

The Outer Membrane (OM)

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Gram negative cell wall

o The side of the OM that faces the outside contains the lipopolysaccharide.

o Porins are proteins that form pores in the outer membrane wide enough to allow passage of most small hydrophilic molecules. This allows migration of these molecules into the periplasmic space for transport across the cytoplasmic membrane.

o Summary of functions of the outer membrane in Gram negative cells:

Selective barrier.

Keeps enzymes in periplasm (see next page).

Stabilizes cells exchanging DNA.

Pathogenic properties.

Bacteriophage (bacterial virus) receptors - although this is a function the cell would rather not have.

Outer Member (OM) of the Gram- cell wall.

Lipo-proteins strongly bind the peptioglycan to the outer membrane.

Periplasmic space.

Cell Membrane proteins.

Bacterial Cell Walls

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The periplasmic space in-between the inner, cell membrane and the peptidoglycan contains many different proteins. These proteins function to detect the environment, and modify, and transport needed nutrients into the cell. Some examples of periplasmic proteins include:

A. Hydrolytic enzymes-

Examples: 1. Proteases - degrade proteins

2. Endonucleases - degrade nucleic acids

B. Binding proteins - recognize specific nutrients (for example, sugars and vitamins) and transport them across membrane.

C. Chemoreceptors - Helps the cell interpret chemical composition of its environment

Let's sum up the differences between G + and G- cells:

Property Gram Positive Gram NegativeThickness of wall 20-80 nm 10 nmNumber of layers in wall 1 2Peptidoglycan content >50% 10-20%Teichoic acid in wall + -Lipopolysaccharide 0 13%Sensitive to penicillin + - (not as much)Digested by lysozyme + - (not as much)http://www.bact.wisc.edu/MicrotextBook/BacterialStructure/MoreCellWall.html

Bacterial Cell Walls

Periplasmic space

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e. Bacteria Lacking Cell Walls

Ex: Mycoplasma pneumoniae

Bacteria without cell walls are not affected by penicillin or lysozyme.

For most bacterial cells, the cell wall is critical to cell survival, yet there are some bacterial cells without cell walls. Mycoplasma species are one example, and they are very wide-spread. They are the smallest known cells (0.2-0.3 micrometers) – almost as small as the largest viruses (poxviruses). They also have the smallest genome of any cell-about 650 genes (about 1/5 the number in E. coli). Mycoplasma are know to cause many plant diseases. Due to the lack of a cell wall, Mycoplasma have unusually tough membranes (3 layers) that are more resistant to rupture than other bacteria. The presence of sterols in the membrane also contributes to their durability. Many Mycoplasma are also pleomorphic.3

Click below for more info on Mycoplasma pneumoniae http://www.emedicine.com/med/topic1540.htm

3 Having no defined shape. Bacterial cells that have no cell wall will often be pleomorphic. However, there are also microbes with cell walls that have this property, and the growth state of the microbe sometimes influences this.

Bacterial Cell Walls

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2. Archaeal Cell Walls

a. Archaeal cells have more variations in their cell wall chemistries4.

b. They never contain true peptidoglycan, but a few have a similar molecule (NAG is present but a different molecule replaces NAM). Penicillin is ineffective in inhibiting the synthesis and lysozyme cannot break the bonds in this type of cell wall.

c. Some archaea do not have cell walls (eg Thermoplasma).

3. Eukaryotic Cell Walls

a. Plants, fungi, and some protists contain a cell wall, but the chemical composition is different from Bacteria and Archaea.

b. There is never peptidoglycan.

c. Animals and protozoa do not have cell walls.

4 Methanosarcina sp. cell walls contain non-sulfated polysaccharides

Halococcus sp. contain sulfated polysaccharides similar to Methanosarcina sp.

Halobacterium sp. contain negatively charged acidic amino acids in their cell walls which counteract the positive charges of the high Na+ environment. Therefore, cells lyse in NaCl concentrations below 15%.

Methanomicrobium sp. & Methanococcus sp. cell walls are exclusively made up of proteins.

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C. Structures External to the Cell Wall (anchored to the cell wall or the plasma membrane)

1. Glycocalyx: Substances that completely surround the outside of the cell wall.

a. Functions

1) Attachment to surfaces.

Most prokaryotic cells adhere to each other.

Some bacteria adhere to rocks (aquatic bacteria) and other solid surfaces.

Some pathogenic bacteria adhere to animal tissues (ex: respiratory tract).

Some are involved in plaque formation leading to dental caries.

2) Protection from environment (slows dehydration).

3) Entrapment of nutrients.

b. Bacterial Glycocalyx: (Capsules and Slime layers)

Usually the capsule is chemically polysaccharides.  It is thick and firmly attached to the cell wall, very dense. Found in pneumonia causing pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, and Klebsiella pneomoniae. Capsulated variants are pathogenic whereas non-capsulated variants of the same species are non-pathogenic. Capsules protect the bacteria against human white blood cells that engulf and digest the bacterial cells.

-Ex: Streptococcus pneumoniae

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Notes:

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c. Slime layers: Chemically similar to capsules but less firmly attached, thinner, and less dense.

Functions: Basically the same as the capsule but they are not associated with pathogenicity.

d. Eukaryotic and Archaeal cells also have a sticky glycocalyx which functions for: cell-to-cell attachment, cell recognition, or strengthening of cell surface.

2. Movement Appendages

a. Flagella: Protein appendages, anchored in the plasma membrane

Some Bacterial, Archaeal, and Eukaryotic species have flagella, but the molecular structure differs between the three groups.

Arrangements:

TEXT: Fig. 4.7 p. 81, Fig. 4.9 p. 83

b. Axial filaments: Bundles of fibers found beneath an outer sheath but outside of the cell wall. Only found in bacterial spirochete

TEXT: Fig. 4.11 p. 84

3. Attachment appendages5

‘Attachment Pili’: Attachment for pathogenic bacteria to human tissues (Often, also called fimbriae). Ex. Neisseria gonorrhoeae

Other attachment configurations include protein networks to which the cells may anchor themselves in large groups.

4. Cell Surface Molecules

5 Also may act as receptor sites for attachment of some pathogens.

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5. Bacteria only! DNA Exchange Appendages

(Ex. E. coli)

Conjugation Pili (‘sex’ pili)

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D. Structures Internal to the Plasma Membrane

1. Structures Common to Both Prokaryotic and Eukaryotic Cells

a. Cytoplasm: All components internal to the plasma membraneApproximately 80% water. Approximately 20% enzymes, organic compounds, dissolved subst., organelles, DNA...

b. Genetic Material- DNA

Comparing Prokaryotic and Eukaryotic DNA:

1) Prokaryotic:

Nuclear Region (Nucleoid): Area in the cytoplasm which contains the large, circular bacterial chromosome (s)6

Plasmids: Free-floating, smaller, circular5 pieces of DNA that are in no way connected to the large bacterial chromosome in the nucleoid

o Usually, the genes on plasmids are not essential to the life of the bacteria but benefit the organism in some way.

o The genetic information supplements the chromosomal genetic information with…

o Plasmids can be copied and transferred to another bacterial cell

o Often bacterial plasmids are used in genetic engineering.

6 Some species (relatively rare) of bacteria have been known to have linear chromosomes and plasmids.

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2) Eukaryotic:

Several linear chromosomes contain the DNA

Nucleus TEXT Fig. 4.24 p. 102

c. Ribosomes

1) Sites of protein synthesis

2) ~10,000 ribosomes in Archaea & Bacteria depending on growth rates but many more in Eucarya

3) Composed of proteins and rRNA

4) Comparing Bacterial, Archeal and Eukaryal ribosomes:

a) Bacterial and Archael ribosomes are similar in size to each other (both smaller than eukaryotic ribosomes) but have different rRNA and protein components.

b) All three cell types have different rRNA molecules and proteins. However the archaeal and eukaryal rRNA components are more similar to each other than to bacteria.

c) Because the three cell types have differences in their ribosome size and molecular structure, different chemicals will interfere in protein synthesis.

Examples:

o Archaea and Eukarya are not sensitive to antibiotics that inhibit bacterial ribosomes: tetracycline, erythromycin, chloramphenicol, streptomycin

o However, the diptheria toxin & anisomycin affects ribosomes of archaea but not bacteria.

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d. Inclusions

1) Structures that appear as granules or globules and serve as storage deposits.2) Not separated by membranes.

3) Examples of stored materials:

Nutrient and Energy reserves (carbon, etc.).

Metabolic deposits: Ex: sulfur deposits as a result of metabolism (some photosynthetic bacteria).

http://trishul.sci.gu.edu.au/courses/ss12bmi/microbe_structure.html Metachromatic granules.

4) Most eukaryotes also have inclusions which function as reserves of materials.

2. Bacteria only! Endospores (‘spores’)

a. Tough, inner, dormant (‘resting’) structures that allow the bacterium to survive under poor environmental conditions (ex: low in nutrient supplies).

b. They are Gram-positive and usually rod-shaped, but there are exceptions. Mainly found in the genera Bacillus and Clostridium.c. Resistant to: heat, acid, radiation, chemicals, disinfectants, dehydration, and lack of nutrients due to the thick coat, dehydrated nature, and a chemical called dipicolinic acid.

Example- heat resistance:

Species Time required to kill a suspension in

 C. botulinum: endospore-forming    2-6 hours at 100oC (boiling water)

 C. tetani: endospore-forming    1-3 hours at 100oC

 E. coli & S. aureus: non-endospore formers  Killed almost immediately at 100oC, 30 minutes at 70o C7

d. The spore can be differentiated into 4 distinct parts:

7 oF = (1.8 x oC) + 32

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-Core: Only contain a few essentials for life- Nucleic acids, ribosomes, low/no levels of enzyme activity, dipicolonic acid & low water content.

-Cortex: Surrounds the core, mainly peptidoglycan

-Coat: Surrounds the cortex, mainly protein

-Exosporium: The outer most thin layer

e. Sporulation and Germination

TEXT Fig. 4.21 p. 97

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Importance of endospores: Self-reading

-Some spore-formers are pathogens of animals, usually due to the production of powerful toxins. Bacillus anthracis causes anthrax, a disease of domestic animals (cattle, sheep, etc.) which may be transmitted to humans. Clostridium botulinum causes botulism, a form of food poisoning. Clostridium tetani is the agent of tetanus.

-Food industries often heat-treat products to reduce microbial spoilage & kill pathogens; spore-formers are a problem (look for swelling of tins).

-Many are found in soils --> where spores may germinate to produce toxins --> infect wounds.

-Some strains were being developed for biological warfare e.g., B. anthracis (anthrax).

-Some strains produce important biopesticides (biotechnology) e.g., B. thuringiensis produces toxic proteins against mosquito & blackfly larvae. Commercial variants are available which produce toxins towards slightly different insect pests; for example Bt corn (the toxin kills corn borer).

-Spores which have ‘germinated’ have been found in 7200 year old temples, mummies, and from the GI tract of a bee preserved in amber (over one-million years old).http://trishul.sci.gu.edu.au/courses/ss12bmi/microbe_structure.html

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3. Eukaryotes only: Complexity, Compartmentalization, MEMBRANES

a. Cytoskeleton: Functions to maintain structure, move cellular components around the cell, and cell movement.

-Composed of protein rods and tubules in a complex network throughout the cell

b. Chloroplasts: Found in photosynthetic eukaryotes (plants and algae)

c. Mitochondria

1. Function in cellular respiration: Glucose is broken down and the energy is stored in ATP.

2. ‘Powerhouse’ of the cell

d. Endoplasmic reticulum (ER) and Golgi complex

1. Organelles composed of folded and elongated stacked membranes, respectively.

2. Involved in...

1) Molecule modification2) Membrane synthesis3) Molecule storage4) Molecule transport

e. Lysosomes & Peroxisomes: Contain digestive and detoxifying enzymes, respectively

f. Vacuoles and Vesicles: Storage, transport, excretion of waste

g. Centrioles

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III. Progression from Prokaryotic Cells to Eukaryotic Cells

Endosymbiotic Theory:-Mitochondria and Chloroplasts

A. Prokaryotic-like cell engulfed smaller prokaryotic-like cell in a manner similar to endocytosis; the engulfed cell was not destroyed and remained in a symbiotic relationship with the larger cell.

B. Supporting evidence:

1. Mitochondria & chloroplast ribosomes are the same size as bacteria and archae; rRNA sequence shows similarity to some archaea & bacteria.

2.

3.

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Exam Review

Cellular Organization

1. Know the 3 domains of life, the major groups within each domain, and the types of information that was used to create this classification scheme. 2. Bacterial Cells: Know the general characteristics of Bacteria (size, shapes, arrangements). Be able to label bacterial structures on a drawing of a bacterial cell.

3. Archaeal Cells: Know the general characteristics concerning Archaeal cells (size, shapes, habitats).

4. Eukaryal Cells: Know the general characteristics concerning Eukaryotic cells. Know one hypothesis for the compartmentalization of eukaryotic functions into various organelles.

5. Know the chemical composition of the plasma membrane and its functions. Be able to describe the term ‘semipermeable’ or ‘selectively permeable’.

6. Understand the five ways that cells transport substances across the plasma membrane (be able to compare/contrast them). Be able to describe osmosis and isotonic/hypotonic/hypertonic solutions.

7. What differences are there between eukaryal and prokaryotic transport across the plasma membrane (i.e., group translocation and cytosis)?

8. Know the functions of some of the various proteins in the plasma membrane.

9. Know examples of functions of the cell wall. Be able to describe the chemical components of a bacterial cell wall.

10. Know the differences between Gram positive and Gram negative cell walls. Know the structure and the importance of the outer membrane to Gram negative bacteria.

11. How do the bacterial cell walls affect disease and disease treatment?

12. Be able to give an example of a bacterium without a cell wall.

13. Briefly describe Archaeal cell walls and their differences from bacterial cell walls.

14. Briefly describe Eukaryotic cell walls and their chemical composition.

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15. Be able to define/describe and list the functions of the glycocalyx.

16. Be able to describe the experiments performed on Streptococcus pneumoniae concerning the capsule and the importance of the experiments concerning knowledge of bacterial gene transfer and the identity of the genetic material.

17. Be able to define/describe and list the functions of the following bacterial structures outside of the cell wall: movement appendages, attachment appendages, cell surface molecules.

18. Compare transformation and conjugation.

19. Be able to define/describe the terms cytoplasm, organelle, membrane-bound.

20. Compare Prokaryotic and Eukaryotic DNA (definitions/descriptions): nucleus, nucleoid, plasmids.

21. Be able to define/describe and list the functions of ribosomes and inclusions. Compare Bacterial, Archael, and Eukaryotic ribosome structure.

22. Know the importance of bacterial plasmids to bacterial gene transfer, resistance, toxins, and genetic engineering.

23. Define and know the characteristics of endospores and examples of spore-forming bacteria. What are endospores resistant to? What is the structure of an endospore, and what is its chemical composition? Know the importance of endospores to disease, food spoilage, wounds, biological warfare, and biotechnology. Define the terms sporulation, germination, vegetative cell.

24. Be able to describe structures only found in eukaryotic cells.

25. Describe the Endosymbiotic theory: Organelles involved, theory description, supporting evidence.

26. Be able to list bacterial structures targeted by antibiotics and other drugs. Why are these structures targeted? Be able to list antibiotics and chemicals that do not affect bacteria but that do affect Archaea and Eukaryal cells.

27. Be able to show similarities and differences between the Archaea and other forms of life.

28. In what way are bacteria more like eukaryotes than archaea?

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29. What structures do all cell types have in common? Although these structures are found in all types of cells, how are they different -in the details?

30. Be able to answer the following type of question:

Which one of the following cellular molecules or structures is primarily involved in the following life process: Response to the environment ( example)

a. Endoplasmic reticulum b. Cell surface molecules c. Ribosomes d. Inclusions

31. Be able to answer the following type of question:

According to available information, state whether the descriptions in questions 10-16 best depict: a) Bacterial cells only, b) Archaeal cells only, c) Eukaryotic cells only, d) All three types of cells or e) archaeal and eukaryotic cells only.

(Example)

1. Phospholipids in the plasma membreane may contain branched isoprene chains and an ether linkage between the isoprenes and L-glycerol

2. Undergo passive diffusion across the plasma membrane

32. Know the definitions of all terms in the handouts.

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