Lesson 1 ProkaryoticCellsPowerPoint

7/25/2019 Lesson 1 ProkaryoticCellsPowerPoint

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Lecture 1

Prokaryote CellStructure & Function

Cell Diagram: Mariana Ruiz, pub domain


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Size of Living Things

Diagrams: http://www.cellsalive.com/howbig.htm

1 m = 100 cm = 1,000mm = 1,000,000 m = 1,000,000,000nm

1mm = 1000 m = 1000000nm

1 m = 1000nm
http://en.wikipedia.org/wiki/Image:Relative_scale.svghttp://en.wikipedia.org/wiki/Image:Relative_scale.svg


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The Cellular Level of Organization

Living things are constructed of cells.

Living things may be unicellularor multicellular.

Cell structure is diverse but all cells share common characteristics.

Cells are smallso they can exchange materials with their surroundings.

Surface area relative to the volume decreases as size of cell increases.- limits the size of cells

___________________ states:

1. All organisms are composed of one or more cells.

2. Cells are the basic unit of structure and function in organisms.

3. All cells come only from other cells.

CELL THEORY


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Two basic types of cells

Diagrams:Prokaryotic & Eukaryotic Cell, Mariana Ruiz

__________________________________________

PROKARYOTIC CELLS

(PROKARYOTES)

EUKARYOTIC CELLS

(EUKARYOTES)


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Prokaryotes

Tell me about Prokaryotes

Binary Fission

Diagrams:Prokaryotic Mariana Ruiz

Binary Fission, JW Schmidt


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Prokaryote Genetics

___________

Region of cytoplasm where chromosomal DNA is located.

Usually a singular, circular chromosome

____________

Small extra piece of chromosome/genetic material.

5 - 100 genes

Not critical to everyday functions.

Can provide genetic information to promote:

- Antibiotic resistance- Virulence factors

(molecules produced by pathogen that specifically influence host's function toallow the pathogen to thrive)

- Promote conjugation(transfer of genetic material between bacteria through cell-to-cell contact)

CONJUGATION OF MICROBIAL CELLS

NUCLEOID

PLASMID


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Prokaryotes

______________

Also known as proto-plasm.

Gel-like matrix of water, enzymes,nutrients, wastes, and gases and containscell structures.

Location of growth, metabolism, andreplication.

______________

Bacterias way of storing nutrients

Staining of some granules aids inidentification

STRUCTURE OF MICOBIAL CELLS

CYTOPLASM

GRANULES


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Prokaryotes

_______________

Found within cytoplasm or attached to plasma membrane.

What are they made of?

What do they do?

Composed of a small (30S) subunit and a large (50S) subunit.Cell may contain thousands of ribosomes.

_________________

Cellular "scaffolding" or "skeleton" within the cytoplasm.

Major advance in prokaryotic cell biology in the last decadehas been discovery of the prokaryotic cytoskeleton.

Previously thought to be a feature only of eukaryotic cells.

Eukaryotic Cells

Diagrams/Photos:

Fluorescent Cell: NIH, Pub Domain

RIBOSOME

CYTOSKELETON


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Prokaryotes - Plasma Membrane

Diagrams:

Prokaryotic Cell, Mariana Ruiz

Membrane: NIST

Separates the cell from its environment.

Phospholipid molecules oriented so that hydrophilic heads directed outward and

hydrophobic tails directed inward.

Proteins embedded in two layers of lipids (lipid bilayer).

___________________ to allow substances to pass into and out of the cell.SEMI-PERMEABLE


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Prokaryotes Plasma Membrane as a arrier

Primary function of plasma membrane regulate

movement of molecules entering or leaving cell.

Movement of molecules across plasma membrane requiresenergy.

PASSIVE TRANSPORTMovement of molecules is passive if no energy sources ofthe cell are expended.

_____________ = when molecules move from a higher toa lower concentration.

What type of things might affect the rate of diffusion?

Diffusion Animation: biologycorner.com

DIFFUSION


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Prokaryotes Plasma Membrane as a Barrier

PASSIVE TRANSPORT (Continued)

_____________ DiffusionProteins assist in diffusion of molecules across plasma membrane.

Movement only occurs in the presence of a concentration gradient.

Some molecules move across the membrane more quickly if diffusion is facilitatedby a carrier molecule.

Diagram:

Facilitated diffusion, Mariana Ruiz

FACILITATED


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Osmosis

Diffusion of ________ across the plasma membrane.

Environment surrounding cells may contain amounts ofdissolved substances (solutes) that areequal toless thangreater thanthose found within the cell.

Tonicity

_________________: no net movement of waterbetween cell and environment

_________________: a higher concentration ofsolute.

_________________: a lower concentration of solute.

Water will always move toward a hypertonicenvironment!!

Diagrams:

Osmosis - www.scienceaid.co.uk/biology/plants/osmosis.html

Blood Cells: Mariana Ruiz

WATER

ISOTONIC

HYPERTONIC

HYPOTONIC
http://www.scienceaid.co.uk/biology/plants/osmosis.htmlhttp://www.scienceaid.co.uk/biology/plants/osmosis.html


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_______________ TRANSPORT

How most molecules move across the plasma membrane.Analogous to a pump moving water uphill.

Types of active transport are classified by type of energy used to drive molecules acrossmembranes.

ATP Driven Active TransportEnergy from adenosine triphosphate (ATP) drives substances across the plasma membrane

with the aid of carrier molecules.

Diagram:

Source unknown

ACTIVE


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Peptidoglycan- Rigid mechanical support- Freely permeable to solutes

Peptidoglycan is a huge polymer of interlocking chains ofidentical peptidoglycan monomers.

Backbone of peptidoglycan molecule composed of twoderivatives of glucose:

N-acetylglucosamine (NAG)N-acetlymuramic acid (NAM)

NAG / NAM strands are connected by interpeptide bridges.

Prokaryotes Cell Wall

Image:

Peptindoglycan Structure: NicolasGrandjean


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From the peptidoglycan inwards all bacteria are very similar. Goingfurther out, the bacterial world divides into two major classes (plus acouple of odd types). These are:

Gram-positive Gram-negative

Prokaryotes - Cell Wall

Images: PHIL Public Health Image Library


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Prokaryotes - Cell Wall: Gram-Negative & Gram-Positive

Image:

Prokaryotic Cell, Mariana Ruiz

Gram +-, Julian Onions


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Why are these differencesin cell wall structure so

important?

Images: Sources unknown


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Prokaryotes - Glycocalyx

Some bacteria have anadditional layeroutside of the cell wallcalled the glycocalyx.

This additional layer cancome in one of twoforms:

1. Slime Layer2. Capsule



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Some bacteria have an additional layer outside of the cell wallcalled the glycocalyx.

This additional layer can come in one of two forms:

1.______________________glycoproteins loosely associated with the cell wall.

Slime layers cause bacteria to adhere to solid surfaces and helpprevent the cell from drying out.

StreptococcusThe slime layer of Gram+ Streptococcus mutans allows it toaccumulate on tooth enamel (yuck mouth and one of the causes ofcavities).

Other bacteria in the mouth become trapped in the slime and forma biofilm & eventually a buildup of plaque.

StaphylococcusThe slime layer of Gram+ Staphylococcusallows it to thrive in thesalty, hypertonic environment of the skin.

Glycocalyces are not specific to Gram+ or Gram- bacteria,sometimes only some members of a certain species (strains) have aglycocalyx, whereas others dont.


SLIME LAYER


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2.___________________polysaccharides firmly attached tothe cell wall.

Capsules adhere to solid surfaces and tonutrients in the environment.

Adhesive power of capsules is a majorfactor in the initiation of some bacterialdiseases. Capsule also protect bacteriafrom being phagocitized by cells of thehosts immune system.

STRUCTURE OF PROKAROTIC CELLS

CAPSULE


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Bacterial Capsule and Meningococcal Infection

Meningococcal infection is caused by meningococcalbacteria (Neisseria meningitidis).

Causes:1. meningococcal meningitis (infection of the

meninges/spinal cord)2. meningococcal septicaemia (blood poisoning).

Of the two forms, meningococcal septicaemia is themost dangerous.

Meningococcal bacteria are the most common causeof bacterial meningitis.

Approximately 5% of people who suffer frommeningococcal meningitis will die.


Meningococcal bacteria grow

in pairs called diplococci often

surrounded by a capsule coat.

Over a million of these would

fit on the head of a pin.

http://www.meningitisuk.org/about-meningitis/bacterial-meningitis.htm
http://www.meningitisuk.org/about-meningitis/bacterial-meningitis.htmhttp://www.meningitisuk.org/about-meningitis/bacterial-meningitis.htm


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Prokaryotes - Endospores

Dormant, tough, non-reproductive

structure produced by smallnumber of bacteria.

Primary function of endospores:Allow bacteria to survive in

suspended animation whenenvironmental conditions arenot suitable. When conditions

are right the endospore willsprout a living bacterium.

Resistant to radiation,desiccation, lysozyme,temperature, starvation, andchemical disinfectants.

Endospores commonly found in soiland water, where they maysurvive for long periods oftime.

A stained preparation of Bacillussubtilis showing endospores as green

and the vegetative cell as red

Image:

Stain: Jerry Keplinger, James H. Quillen College of Medicine

Procedure: Source link no longer works



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_____________________

The most significant cause of pseudomembranous colitis

Severe infection of the colon, often happening after normal gut flora is eradicated byuse of antibiotics. The C. difficile bacteria naturally resides in the body, butbecomes overgrown.

C. difficile overgrowth is harmful because the bacterium releases toxins that cause:

* Bloating and constipation* Diarrhea with abdominal pain* Severe diarrhea with mucus and blood present in feces* Body aches and severe abdominal pain caused from ulcerated intestines

Treatment includes specific anticlostridial antibiotics, e.g. metronidazole orvancomycin.

News story link: http://www.thesun.co.uk/sol/homepage/news/article860499.ece


Clostridium difficile (aka C dif or CDF)
http://www.thesun.co.uk/sol/homepage/news/article860499.ecehttp://www.thesun.co.uk/sol/homepage/news/article860499.ece


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Prokaryotes Surface Appendages

Some prokaryotes have distinct appendages that allow themto move about or adhere to solid surfaces.

Consist of delicate stands of proteins.

___________Long, thin extensions that allow some bacteria to move about

freely in aqueous environments.

__________________ (endoflagella)Wind around bacteria, causing movement in waves.

____________Most Gram- bacteria have these short, fine appendages

surrounding the cell. Gram+ bacteria dont have.

No role in motility. Help bacteria adhere to solidsurfaces. Major factor in virulence.

____________Tubes that are longer than fimbriae, usually shorter than

flagella. Use for movement, like grappling hooks, and alsouse conjugation pili (singular = pilus) to transfer plasmids.

Images:

Flagella: Mike Jones Wiki

Axial Filament: Indiana USchool of Med

EColi: Pub Library of Science

FLAGELLA

AXIAL FILAMENTS

FIMBRIA

PILI


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Neisseria gonorrhoeae

Gonorrhoeae one of the most communicable disease in the US.

125 cases per 100,000. Teens 15-19 yo 634 cases per 100,000. Young adults20-25 460 per 100,000.

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Lesson 1 ProkaryoticCellsPowerPoint