Prokaryotic Cells. Prokaryotes PLASMA MEMBRANE CELL WALL GLYCOCALYX CAPSULE SLIME LAYER FLAGELLUM SEX PILUS FIMBRAE

Prokaryotic CellsProkaryotic Cells

ProkaryotesProkaryotes

PLASMA MEMBRANEPLASMA MEMBRANE CELL WALLCELL WALL GLYCOCALYXGLYCOCALYX

CAPSULECAPSULE SLIME LAYERSLIME LAYER

FLAGELLUMFLAGELLUM SEX PILUSSEX PILUS FIMBRAEFIMBRAE

PLASMA MEMBRANEPLASMA MEMBRANE

All cells (Prokaryote and Eukaryote) have All cells (Prokaryote and Eukaryote) have a plasma membrane.a plasma membrane.

It holds the organelles inside of the cell. It holds the organelles inside of the cell. Any substance that can rupture the Any substance that can rupture the

plasma membrane will kill the whole plasma membrane will kill the whole organismorganism

Alcohol, soaps, and other detergents Alcohol, soaps, and other detergents easily rupture the plasma membrane.easily rupture the plasma membrane.


The plasma membrane is The plasma membrane is semipermiablesemipermiable Allows some substances to come and go (oxygen Allows some substances to come and go (oxygen

and water molecules), but does not allow other and water molecules), but does not allow other things to get inside or leave.things to get inside or leave.

It regulates the flow of nutrients in the cell. It regulates the flow of nutrients in the cell. It allows low molecular weight (small sized) It allows low molecular weight (small sized)

substances (such as water) to get in and out substances (such as water) to get in and out depending on their concentration within the cell and depending on their concentration within the cell and outside of it. This is called outside of it. This is called diffusiondiffusion, and does not , and does not require the cell to expend any energy.require the cell to expend any energy.

Plasma MembranePlasma Membrane Phospholipid bilayerPhospholipid bilayer Peripheral proteinsPeripheral proteins Integral proteinsIntegral proteins Transport proteinsTransport proteins

Figure 4.14b

Movement Across MembranesMovement Across Membranes

Figure 4.17


Hypertonic solution: salty waterHypertonic solution: salty water The concentration of salt outside of the cell is higher than the The concentration of salt outside of the cell is higher than the

inside of the cell, so the water will follow salt out, and the cell inside of the cell, so the water will follow salt out, and the cell will shrink. will shrink.

Hypotonic solution: pure waterHypotonic solution: pure water More salt inside of the cell; water will diffuse into the cell, More salt inside of the cell; water will diffuse into the cell,

causing the cell to explode (osmotic shock).causing the cell to explode (osmotic shock). The cell wall of bacteria is rigid and protects the organism from The cell wall of bacteria is rigid and protects the organism from

osmotic shock. osmotic shock. Isotonic solution: same amount of salt on the Isotonic solution: same amount of salt on the

inside and outside of the cellinside and outside of the cell Normally, there is equilibrium inside and outside of the cell.Normally, there is equilibrium inside and outside of the cell.

Figure 4.18c-e

OsmosisOsmosis Movement of water Movement of water

across a selectively across a selectively permeable membrane permeable membrane from an area of high from an area of high water concentration to an water concentration to an area of lower water.area of lower water.

Osmotic pressureOsmotic pressure The pressure needed to The pressure needed to

stop the movement of stop the movement of water across the water across the membrane.membrane.

Movement Across Movement Across MembranesMembranes

Figure 4.18a

PLASMA MEMBRANEPLASMA MEMBRANE Phospholipid bilayerPhospholipid bilayer. .

Two layers of a compound Two layers of a compound consisting of phosphates and consisting of phosphates and lipids (fats). lipids (fats).

The outer and inner sides The outer and inner sides of the membrane are water of the membrane are water soluble, and the area soluble, and the area between is not water between is not water soluble. soluble. This gives the membrane This gives the membrane

semipermiablity, which allows semipermiablity, which allows it to take in certain it to take in certain substances and keep out substances and keep out other substances.other substances.


LipoproteinsLipoproteins (LP): made of lipid (fat) (LP): made of lipid (fat) and proteins. and proteins. These special proteins can transport larger These special proteins can transport larger

molecules (like sugars) directly into the cell. molecules (like sugars) directly into the cell.

This is called This is called active transportactive transport. . It requires the cell to spend some energy in It requires the cell to spend some energy in

the form of ATP.the form of ATP.

Movement Across Membranes:Movement Across Membranes:Active TransportActive Transport

Figure 4.17


Gram negative organisms have an inner Gram negative organisms have an inner and an outer plasma membrane, and an outer plasma membrane, whereas Gram positive organisms only whereas Gram positive organisms only have one plasma membrane.have one plasma membrane.

The inner from the outer plasma The inner from the outer plasma membrane in a Gram negative bacterium membrane in a Gram negative bacterium is separated by a cell wall.is separated by a cell wall.

Plasma membrane

Outer plasma membrane

GRAM POSITIVE GRAM NEGATIVE

Cell Wall


In Gram negative organisms, the outer In Gram negative organisms, the outer plasma membrane contains a special plasma membrane contains a special structure called a structure called a lipopolysachharidelipopolysachharide (LPS), which means it is made of lipids (LPS), which means it is made of lipids (fats) and many sugars (fats) and many sugars (polysaccharides). (polysaccharides).

The LPS of the plasma membrane in The LPS of the plasma membrane in bacteria is referred to as an bacteria is referred to as an O antigenO antigen. .

Within the LPS membrane is a toxin Within the LPS membrane is a toxin called Lipid A. called Lipid A.

Inner plasma membrane


GRAM NEGATIVE

Cell Wall

LPS

O Antigen

Lipid A

LPS

CELL WALLCELL WALL

More complex in Prokaryotes (bacteria) than in More complex in Prokaryotes (bacteria) than in Eukaryotes (humans). Eukaryotes (humans).

Its rigidity keeps the organism from exploding from Its rigidity keeps the organism from exploding from osmotic shock.osmotic shock.

Composed of Composed of peptidoglycanpeptidoglycan, which is a combination , which is a combination of peptide (protein) and glycan (sugar). of peptide (protein) and glycan (sugar).

Peptidoglycan is only found in bacteria. Peptidoglycan is only found in bacteria. MycoplasmaMycoplasma (causes TB or leprosy, depending on (causes TB or leprosy, depending on

the species) is the only bacteria without a normal cell the species) is the only bacteria without a normal cell wall (its cell wall is 60% waxy). It is neither Gram-wall (its cell wall is 60% waxy). It is neither Gram-positive nor Gram-negative. It is called “Acid-fast” positive nor Gram-negative. It is called “Acid-fast” because it takes an acidic stain to color it. because it takes an acidic stain to color it.

Peptidoglycan Peptidoglycan

Consists of a chain of two types of sugars (NAM and Consists of a chain of two types of sugars (NAM and NAG) linked by proteins. NAG) linked by proteins.

The sugars are arranged in this order: NAG-NAM-The sugars are arranged in this order: NAG-NAM-NAG.NAG.

NAM

NAM

NAMNAG

NAG

CELL WALLCELL WALL

Not only do Gram negative bacteria have Not only do Gram negative bacteria have less peptidoglycan than Gram positives, less peptidoglycan than Gram positives, they also have an inner and outer plasma they also have an inner and outer plasma membrane. membrane.

The outer plasma membrane is external The outer plasma membrane is external to the cell wall, and the inner plasma to the cell wall, and the inner plasma membrane is internal to the cell wall. membrane is internal to the cell wall.

Outer membrane

Peptidoglycan

GRAM NEGATIVE GRAM POSITIVE

CELL WALLCELL WALL

Gram positive organisms have much more peptidoglycan Gram positive organisms have much more peptidoglycan than Gram negatives. than Gram negatives.

The dye enters the cytoplasm of both Gram positive and The dye enters the cytoplasm of both Gram positive and negative cells.negative cells.

The iodine forms large crystals with the dye that are too The iodine forms large crystals with the dye that are too large to escape through the cell wall.large to escape through the cell wall.

Alcohol dissolves the outer membrane of the gram-Alcohol dissolves the outer membrane of the gram-negative cells and leaves small holes in the thin negative cells and leaves small holes in the thin peptidoglycan layer through which the Crystal Violet-peptidoglycan layer through which the Crystal Violet-iodine complex leaks out. iodine complex leaks out.

Although gram-positive and gram-negative cells both Although gram-positive and gram-negative cells both absorb safranin, the pink color of safranin is masked by absorb safranin, the pink color of safranin is masked by the darker purple dye previously absorbed by gram-the darker purple dye previously absorbed by gram-positive cells.positive cells.

Plasma membrane



Cell Wall

Crystal Violet added


Iodine Added


Alcohol Added


Safranin added


Final Result

CELL WALLCELL WALL

GRAM POSITIVE GRAM POSITIVE CELL WALLCELL WALL

GRAM NEGATIVE GRAM NEGATIVE CELL WALLCELL WALL

No outer plasma No outer plasma membranemembrane

Inner and outer plasma Inner and outer plasma membranemembrane

Thick peptidoglycanThick peptidoglycan Thin peptidoglycanThin peptidoglycan

Outside cell wallOutside cell wall Usually stickyUsually sticky Extracellular Extracellular

polysaccharide allows polysaccharide allows cell to attachcell to attach

GlycocalyxGlycocalyx

Figure 4.6a, b

GLYCOCALYXGLYCOCALYX

CAPSULECAPSULE SLIME LAYERSLIME LAYER

CAPSULECAPSULE

Non-slimy protein (made of polypeptides) or Non-slimy protein (made of polypeptides) or sugars (polysaccharides) covering the sugars (polysaccharides) covering the bacterium. bacterium.

It is It is neatly organizedneatly organized. . Not every bacterium has a capsule. Not every bacterium has a capsule. Purpose is to store nutrients and inhibited Purpose is to store nutrients and inhibited

phagocytosisphagocytosis The capsule itself is an antigen, called the The capsule itself is an antigen, called the K K

antigenantigen. It stimulates an immune response.. It stimulates an immune response. Example is Example is Mycobacterium tuberculosis.Mycobacterium tuberculosis.

CapsuleCapsule

TB nodules

SLIME LAYERSLIME LAYER

Slimy protein covering the entire Slimy protein covering the entire bacterium. bacterium.

NotNot neatly organized. neatly organized. Not every bacterium has a slime layer. Not every bacterium has a slime layer. Function is to attach to some structure Function is to attach to some structure

in the host. in the host. Example is the bacteria in the mouth. Example is the bacteria in the mouth.

FLAGELLUMFLAGELLUM

Whip-like tail used for Whip-like tail used for motility. motility.

Can observe motility in live Can observe motility in live cells, but can’t see the cells, but can’t see the flagella.flagella.

Requires a special stain, Requires a special stain, and that kills the bacterium. and that kills the bacterium.

Made of a protein called Made of a protein called flagellin. flagellin.

Structure:Structure: FilamentFilament HookHook Turning disks within a Turning disks within a

basil body. basil body.

FLAGELLUMFLAGELLUM

ATP is needed to turn the disk, which ATP is needed to turn the disk, which turns the flagella. turns the flagella.

Chemotaxis: sensing chemicals in the Chemotaxis: sensing chemicals in the environment and moving towards or environment and moving towards or away from them.away from them.

Bacteria flagella contain a protein called Bacteria flagella contain a protein called an an H antigenH antigen (Flagellar antigen). (Flagellar antigen).

FLAGELLAR ANTIGENFLAGELLAR ANTIGEN

There is one strain of There is one strain of E. coliE. coli called called O157.H7 O157.H7

The letter “O” followed by a number The letter “O” followed by a number indicates the type of cell wall indicates the type of cell wall lipopolysaccharide (LPS) and the H7 lipopolysaccharide (LPS) and the H7 indicates the type of flagellar antigen. indicates the type of flagellar antigen.

Flagella arrangements:Flagella arrangements:

Peritricous: Many flagella all around the Peritricous: Many flagella all around the perimeter of the cell.perimeter of the cell.

Lophotrichous: A group of flagella gathered Lophotrichous: A group of flagella gathered at one end of the cell.at one end of the cell.

Amphitrichous: One flagellum coming out of Amphitrichous: One flagellum coming out of each end of the cell.each end of the cell.

Monotrichous: Only one flagellum, comes Monotrichous: Only one flagellum, comes out of one end of the cell out of one end of the cell

Flagella ArrangementFlagella Arrangement

Figure 4.7

Flagella motility:Flagella motility:

Run: move in a straight line from point A Run: move in a straight line from point A to point B.to point B.

Tumble: roll around themselves like a Tumble: roll around themselves like a rock tumbling down a slope.rock tumbling down a slope.

Run and Tumble: Doing both movements Run and Tumble: Doing both movements alternately.alternately.

Motile CellsMotile Cells

Figure 4.9

AXIAL FILAMENTSAXIAL FILAMENTS

Special flagella found only in Special flagella found only in spirochetesspirochetes

Allows the spirochete to move in a Allows the spirochete to move in a motion like a corkscrew. motion like a corkscrew.

This allows it to penetrate tissue. This allows it to penetrate tissue. Example of a spirochete is the Example of a spirochete is the

bacterium that causes syphilis.bacterium that causes syphilis.

EndoflagellaEndoflagella In spirochetesIn spirochetes Anchored at one Anchored at one

end of a cellend of a cell Rotation causes Rotation causes

cell to movecell to move

Axial FilamentsAxial Filaments

Figure 4.10a

SEX PILUSSEX PILUS

Longer than flagellaLonger than flagella Helps cells connect Helps cells connect

to each other during to each other during conjugationconjugation

Pili are used to Pili are used to transfer DNA from transfer DNA from one cell to anotherone cell to another

FIMBRAEFIMBRAE

Hair-like structures Hair-like structures made of protein. made of protein.

In Eukaryotes, they In Eukaryotes, they are called cilia. are called cilia.

In bacteria, fimbrae In bacteria, fimbrae allow them to attach allow them to attach to the host.to the host.

Example is Example is Neisseria Neisseria gonorrhoeaegonorrhoeae (causes (causes gonorrhea). gonorrhea).

Bacterial AntigensBacterial Antigens

O Antigen: LPS of gram-negativeO Antigen: LPS of gram-negative H Antigen: FlagellaH Antigen: Flagella K Antigen: Capsule K Antigen: Capsule

INTERNAL COMPOSITION OF INTERNAL COMPOSITION OF PROKARYOTE CELLSPROKARYOTE CELLS

1. 1. CYTOPLASMCYTOPLASMNUCEOIDNUCEOIDPLASMIDSPLASMIDSRIBOSOMESRIBOSOMES INCLUSIONSINCLUSIONS

2. 2. ENDOSPORESENDOSPORES

CYTOPLASMCYTOPLASM

The watery substance inside of the The watery substance inside of the plasma membrane. plasma membrane.

It is made up of 80% water and contains It is made up of 80% water and contains proteins (enzymes), carbohydrates, and proteins (enzymes), carbohydrates, and lipids. lipids.

NUCEOIDNUCEOID

A nuclear area (prokaryotes have no A nuclear area (prokaryotes have no nucleus). nucleus).

There is only one chromosome, and the There is only one chromosome, and the DNA is circular instead of linear.DNA is circular instead of linear.

Prokaryotes have no histones, which are Prokaryotes have no histones, which are structures eukaryotes use to organize structures eukaryotes use to organize their DNA by wrapping around it.their DNA by wrapping around it.

PLASMIDSPLASMIDS

Small pieces of DNA fragments which Small pieces of DNA fragments which are separate from the chromosome.are separate from the chromosome.

They may carry genes for antibiotic They may carry genes for antibiotic resistance, production of toxins, etc.resistance, production of toxins, etc.

Plasmids can be transferred from one Plasmids can be transferred from one bacterium to another.bacterium to another.

Plasmid DNA is used for gene Plasmid DNA is used for gene manipulation and biotechnology. manipulation and biotechnology.

RIBOSOMESRIBOSOMES

““Protein factories”Protein factories” The cytoplasm can contain 10,000 ribosomesThe cytoplasm can contain 10,000 ribosomes Gives the cytoplasm a granular appearance Gives the cytoplasm a granular appearance Several antibiotics work by inhibiting the Several antibiotics work by inhibiting the

protein synthesis of ribosomes:protein synthesis of ribosomes: StreptomycinStreptomycin GentamicinGentamicin ErythromycinErythromycin Chloramphenicol.Chloramphenicol.

RibosomesRibosomes

Figure 4.6a

RibosomesRibosomes

They are made of two subunits:They are made of two subunits: 30S30S 50S50S

Together, they are called a 70S ribosome unit Together, they are called a 70S ribosome unit (the numbers are NOT added to get this (the numbers are NOT added to get this figure).figure).

Some antibiotics attack the 30S unit Some antibiotics attack the 30S unit (streptomycin and gentamycin), some attack (streptomycin and gentamycin), some attack the 50S unit (erythromycin and the 50S unit (erythromycin and chloramphenicol).chloramphenicol).

RibosomesRibosomes

Figure 4.19

INCLUSIONSINCLUSIONS

Reserve deposits of nutrients within the Reserve deposits of nutrients within the cytoplasm. cytoplasm.

These nutrients can be in the form of These nutrients can be in the form of phosphate, glycogen, starch, and lipids.phosphate, glycogen, starch, and lipids.

ENDOSPORESENDOSPORES

Specialized resting cells formed by gram-Specialized resting cells formed by gram-positive bacteria when essential nutrients positive bacteria when essential nutrients are depletedare depleted

An example is An example is ClostridiumClostridium, which causes , which causes diseases such as gangrene, tetanus, diseases such as gangrene, tetanus, botulism, and food poisoning. botulism, and food poisoning.

Another example is Another example is BacillusBacillus, some , some species of which cause anthrax and food species of which cause anthrax and food poisoning. poisoning.

Figure 4.21a

ENDOSPORESENDOSPORES

Only bacteria make endospores. Only bacteria make endospores. They are highly durable, dehydrated cells with thick They are highly durable, dehydrated cells with thick

walls. walls. They are formed inside the cell membraneThey are formed inside the cell membrane When released into the environment, they can survive When released into the environment, they can survive

extreme heat, lack of water, and exposure to toxic extreme heat, lack of water, and exposure to toxic chemicals and radiation. chemicals and radiation.

Endospores require a special stain to be visualized.Endospores require a special stain to be visualized. Only one cell comes from one endospore, therefore Only one cell comes from one endospore, therefore

sporulation is sporulation is not not reproduction.reproduction.

SPORULATION SPORULATION

The vegetative (parent) cell forms one The vegetative (parent) cell forms one endospore because a key nutrient endospore because a key nutrient becomes unavailable.becomes unavailable.

The cytoplasm of the vegetative cell dries The cytoplasm of the vegetative cell dries up, the cell wall ruptures, and the up, the cell wall ruptures, and the endospore is released into the endospore is released into the environment. environment.

GERMINATION GERMINATION

The endospore returns to its vegetative state.The endospore returns to its vegetative state. This is triggered by a change in the This is triggered by a change in the

environment.environment. Water enters into the endospore, and Water enters into the endospore, and

metabolism resumes. metabolism resumes. They are resistant to heating, freezing, They are resistant to heating, freezing,

desiccation (drying), use of chemicals, and desiccation (drying), use of chemicals, and radiation. radiation.

Endospores can survive in boiling water for Endospores can survive in boiling water for several hours or more.several hours or more.

TYPES OF ENDOSPORESTYPES OF ENDOSPORES

Terminal endosporeTerminal endospore Sub-terminal endosporeSub-terminal endospore Central endosporeCentral endospore

Prokaryotic Cell DrawingProkaryotic Cell Drawing

Documents

Prokaryotic Cells. Prokaryotes PLASMA MEMBRANE CELL WALL GLYCOCALYX CAPSULE SLIME LAYER FLAGELLUM SEX PILUS FIMBRAE