CellsCellsMicrobiology 2314

General Properties of Living General Properties of Living OrganismsOrganisms

• Metabolism

• Growth

• Reproduction

Characteristics of Life?????

• Responsiveness or Irritability

• Conductivity

• Growth

• Respiration

• Digestion

• Metabolism

• Absorption

• Secretion

• Excretion

• Circulation

• Reproduction

Cell TheoryCell Theory• Cells are the fundamental units of life

• Cells are the simplest unit capable of independent existence

• All living things are made of cells

Note: Credit for developing Cell Theory is usually given to two scientists, Theodor Schwann, a zoologist and Matthias Jakob Schleiden, a botanist. In 1839 these two scientists suggested that cells were the basic unit of life. In 1858, Rudolf Virchow concluded that all cells come from pre-existing cells thus completing the theory.

Modern Cell Modern Cell Theory Expands Theory Expands

These Ideas…These Ideas…

• Cells contains hereditary information which is passed from cell to cell during cell division.

• Cells have similar chemical composition, metabolic activities, and physiological functions.

• Cell activity depends on the activities of organelles.

Organizational HierarchyOrganizational Hierarchy

• Biology is hierarchial with each level building on the level below it.

• In order to understand how something is built and how something works, you must look at all of its components and analyze them both individually and together.

Life’s HierarchyLife’s Hierarchy

• Atom / Element

• Molecule / Compound

• Organelle

• Cell

• Tissue

• Organ

• Organ System

• Organism

• Population

• Community

• Ecosystem

• Biosphere

• Atoms form all matter.

• Atoms are the basic building blocks of matter that make up everyday objects. A desk, the air, even you are made up of atoms!

• There are 90 naturally occurring kinds of atoms. Scientists in labs have been able to make about 25 more.

Atom

• Groups of atoms form molecules.

• Molecules come together to form compounds and compounds come together to form organelles

• Organelles can include the nucleus, endoplasmic reticulum, golgi apparatus, mitochondria, etc.

Atom

Organelle

Mitochondria are the 'power plants' of cells that convert organic materials into energy. Mitochondria have their own DNA and may be descended from free-living prokaryotes that were related to Rickettsia bacteria

• The basic unit of life is the cell.

• All living things are composed of one or more cells

• The human body contains about 100 trillion cells.

• There are about 200 different types of cells in the human body.

Atom

Organelle

Cell

• Tissue is a collection of interconnected cells that perform a similar function within an organism.

• The study of tissue is known as histology, or in connection with disease, histopathology

• There are four basic types of tissue in the body of all animals, including the human body and lower multicellular organisms such as insects.

Atom

Organelle

Cell

Tissue

Types of TissuesTypes of Tissues

• Organs are the next level of organization in the body. 

• An organ is a structure that contains at least two different types of tissue functioning together for a common purpose. 

• There are many different organs in the body: the liver, kidneys, heart, even your skin is an organ. 

Atom

Organelle

Cell

Tissue

Organ

• Organ Systems are composed of two or more different organs that work together to provide a common function. 

• There are 10 major organ systems in the human body.

Atom

Organelle

Cell

Tissue

Organ

Organ System

• In biology and ecology, an organism is an individual living system (such as animal, plant, fungus or micro-organism).

• In at least some form, all organisms are capable of reacting to stimuli, reproduction, growth and maintenance as a stable whole.

Atom

Organelle

Cell

Tissue

Organ

Organ System

Organism

Albino Peacock

• An organism may be unicellular or made up, like humans, of many billions of cells (multicelluar) divided into specialized tissues and organs.

• Based on cell type, organisms may be divided into the prokaryotic and eukaryotic groups.

• In biology a population is the collection of organisms or individuals of a particular species located in a specific area.

Atom

Organelle

Cell

Tissue

Organ

Organ System

Organism

Population

• A community includes all the biotic (living) organisms sharing an environment, normally with shared interests.

Atom

Organelle

Cell

Tissue

Organ

Organ System

Organism

Population

Community

• An ecosystem is a natural unit consisting of all the biotic and abiotic elements that composes it.

Atom

Organelle

Cell

Tissue

Organ

Organ System

Organism

Population

Community

Ecosystem

• The biosphere is the part of the earth, including air (atmosphere), land (lithosphere), and water (hydrosphere), within which life occurs, and which biotic processes in turn alter or transform.

• From the broadest point of view, the biosphere is the global ecological system integrating all living beings and their relationships.

Atom

Organelle

Cell

Tissue

Organ

Organ System

Organism

Population

Community

Ecosystem

Biosphere

Cells are 90% water. A mere 2% drop in body water can trigger fuzzy

short-term memory, trouble with basic math, and difficulty focusing

on the computer screen.

Cell Elemental CompositionCell Elemental Composition

• 50% Protein

• 15% Carbohydrate

• 15% Nucleic Acid

• 10% Lipid

• 10% Miscellaneous

Cells are 90% water. Of the remaining molecules present, the dry weight is approximately:

• Proteins are found literally everywhere in your system. From your muscle tissues, to the enzymes that digest your food, to your skin cells, and even within your blood.

• When we take protein in our body through the foods we eat, it gets broken down into smaller compounds called amino acids. Of the 20 amino acids found in the foods we eat, 9 of these are essential.

• All carbs end up as sugar. Starches, or complex carbohydrates, are just longer strings of sugar.

• Lipids are among the fundamental categories of nutrients that are required by our bodies for healthy functioning.

“We are a generation that is computer literate but food illiterate.”

Brief History of Life on EarthBrief History of Life on Earth

• 4.5 Billion Years Ago Earth Formed

• 3.5 Billion Years Ago First Life (Prokaryotic)

• 1.5 Billion Years Ago Eukaryotic Cells Arise

• 0.5 Billion Years Ago Multicellular Eukaryotes

Comparing Prokaryotic and Comparing Prokaryotic and Eukaryotic CellsEukaryotic Cells

Similarities Between the TwoSimilarities Between the Two

• Chemical Composition

• Chemical Reactions

• DNA

• Membrane Bound

• Ribosomes

• Basic Metabolism

• Occur in Diverse Forms

Differences Between the TwoDifferences Between the Two

• Procaryotic cells lack membrane-bound organelles (Including a Nucleus)

• Procaryotic cell walls contain peptidoglycan

Classifying LifeClassifying Life

Life

/ \

Prokaryotes Eukaryotes

/ \ |

Archeabacteria Eubacteria Eukarya (Ancient Bacteria) (True Bacteria) (Everything Else)

Two Groups of ProkaryotesTwo Groups of Prokaryotes

• Archaebacteria

1. Methanogens

2. Halophiles

3. Hyperthermophiles

4. Thermoplasma

• Eubacteria

1. Cyanobacteria

2. Soil Bacteria

3. Nitrogen-Fixing

4. Pathogens

EubacteriaEubacteria

• More Well Known• Can be Pathogenic

ArchaebacteriaArchaebacteria

• Ancient• Non-Pathogenic• Extreme

Environments• Unusual Metabolizing

Abilities• No Peptidoglycan• Resistant to Lysozyme

The hot springs of Yellowstone National Park, USA, were among the first place Archaea were discovered

MethanogensMethanogensAnaerobic Methane

Producers

• Common in wetlands

• Responsible for marsh gas

• Found buried under km of ice in greenland and under dry deserts.

• They are known to be the most common archaebacteria in deep subteranean habitats.

Extreme HalophilesExtreme Halophiles

Salt-Dependent Organisms

Anywhere with a concentration of salt 5 times greater than the salt concentration of the ocean

•The Great Salt Lake, Utah •Owens Lake, California •The Dead Sea

HyperthermophilesHyperthermophilesHeat-Dependent

Organisms

Hyperthermophiles were first discovered in the 1960s in hot springs in Yellowstone National Park, Wyoming.

The most hardy hyperthermophiles thus known live on the superheated walls of deep-sea hydrothermal vents, requiring temperatures of at least 90 °C for survival.

Hyperthermophiles produce some of the bright colors of Grand Prismatic Springs

ThermoplasmaThermoplasma

Heat and Acid

Resistant

Example: Thermoplasma Volcanium

What Happened to the Dinosaurs?

Bacterial ShapesBacterial Shapes

Modified ShapesModified Shapes

• Diplo• Strepto• Staphylo• Vibrio• Tetrad• Pleomorphic – can assume more than 1 shape• Monomorphic – can assume only one shape

Spirillum

Glycocalyx/Slime Capsule/Slime LayerGlycocalyx/Slime Capsule/Slime Layer

Not Really the Same ThingNot Really the Same Thing

• Slime Capsule is a distinct Defined Layer with a Distinct Outer Edge

• Slime Layer is a Poorly Defined Concentration of Slime. It Lessens with Distance.

• Glycocalyx Refers to a Gelatinous Polysaccharide and/or Polypeptide Covering.

Purposes

1. Protects Pathogens from Phagocytosis

2. Enable Adherence to Surfaces

3. Protects Against Desiccation

4. Stores Food Reserves

Case Study 1Case Study 1• The patient was a 22-year-old female with a history of

mitral valve prolapse (a defect of the valve between the left atrium and ventricle caused by a weakening of the tough, connective tissue of the valve leaflets, which allows the valve to project back into the left atrium). She was admitted with complaints of intermittent fevers for 1 month and headaches for 3 weeks. Two weeks before symptoms developed she had undergone a dental procedure.

• Four blood cultures were performed on admission. All four blood cultures demonstrated Gram-positive cocci in chains.

The diagnosis is bacterial endocarditis (a bacterial infection of the tissue lining the inside of the heart; usually involves the heart valves).

The patient had recently had her 6 month dental appointment to have her teeth cleaned.

• During dental procedures, transient bacteremia occurs in up to 80% of individuals.

• Transient bacteremia is defined as the presence of bacteria in the bloodstream for short periods.

• The organisms that cause this are generally of low virulence and are usually easily removed by the reticuloendothelial [filtering and phagocytic] system.

Case Study 2Case Study 2

• This 47-year-old man had a history of sickle cell disease that resulted in many previous hospitalizations for the management of painful crisis.

• The patient had been admitted 9 days prior to the current admission for management of such a crisis, and a right port-a-cath (a central venous catheter that is designed to remain in place for a prolonged period) was placed in his right subclavian vein.

• He was discharged (with port-a-cath remaining) after a 4-day hospitalization.

• On the day of readmission, the patient had right arm discomfort and swelling, a temperature of 38.1C (normal is 37C), and chills. He presented to the hospital emergency room, where he was afebrile. Physical examination was remarkable for right extremity swelling.

• Two blood cultures were obtained (one set through the port-a-cath and one set via a peripheral vein). The two sets of blood cultures grew identical Gram-positive cocci that were catalase positive. The diagnosis is in-line sepsis.

Any indwelling device introduced through the skin places an individual at risk for infection.

Bacteria can produce a slime layer that can enhance their adherence to a wide variety of plastic surfaces.

Slime-producing strains of staphylococci may also be more difficult to eradicate by antimicrobial therapy than non-slime-producing ones due to antibiotic resistance.

FlagellaFlagella

Hook is similar to a universal joint

Basal Body penetrates the cell and causes the flagellum to rotate. It serves as a “motor”.

Filament is actually an extension of the plasma membrane.

Flagella Occur In a Variety of

Forms

Examples of bacterial flagella

arrangement schemes.

A-Monotrichous (one flagella)

B-Lophotrichous (a tuft of flagella)

C- Bipolar Monotrichous (one flagella at both ends)

D-Peritrichous (a hair ball)

• Monopolar Lophotrichous

• Bipolar Lophotrichous

• Peritrichous

Identify This

Identify This

Identify This

Identify This

Flagella Allow for MotilityFlagella Allow for Motility

Bacterial Bacterial MovementMovement

TaxisTaxis

• Positive Taxis• Negative Taxis• Phototaxis• Chemotaxis• Magnetotaxis

Plankton

AntigenAntigen

• Bacteria Flagella is composed of protein which acts as an antigen when introduced into the human body.

• What happens then?

• Why is this beneficial for vaccines?

Axial FilamentsAxial Filaments

(Endoflagellum)(Endoflagellum)

on a Spirocheteon a Spirochete

SpirochetesSpirochetes• Spirochetes are long and slender bacteria that are

tightly coiled, and so look like miniature springs or telephone cords.

Spirochetes Cause Spirochetes Cause Syphilis and Lyme Syphilis and Lyme

DiseaseDisease

Are Spirochetes and Spirilla the Same?

Fimbriae and PiliFimbriae and Pili

Short, Rigid, Hollow, Thin, Protein Appendages

They are NOT involved in motility.

Fimbriae Help Cells Adhere To Surfaces

Pili Join Cells for the Transfer of DNA From One Cell to Another

Together They Produce Biofilms.

This is Biofilm in a Swamp Gas

Reactor

Biofilm on Teeth

The Cell Wall of PeptidoglycanThe Cell Wall of Peptidoglycan

Gram Positive BacteriaHave Thicker Layer of Peptidoglycan and Have Teichoic Acids

Gram Negative BacteriaThinner Layer of Peptidoglycan

Gram + and – Cell Walls

Gram - BacteriaGram - Bacteria• More susceptible to breakage• Thinner layer of peptidoglycan

Outer membrane is strongly negative aiding is resisting phagocytosis and

providing a barrier to antibiotics and

digestive enzymes

Periplasmic space containing specialized proteins and enzymes involved in nutrient

acquisitionIt has Porins and Specific Channel

Proteins

Osmotic EffectsOsmotic Effects

Water Moves Freely Across Membranes to Try and Equalize Concentration

Osmotic Differences in Blood Cells

Lysozyme and PenicillinLysozyme and Penicillin

More Basic Structures of Prokaryotic Cells

Cell Membrane

Cell Cell MembraneMembrane

• Permeability Barrier or Selective Barrier• Prevents cell contents from leaking away• Impermeable to polar and charged

molecules• Contains specific proteins to carry out

selective transport• 50% lipid and 50% protein

Very delicate and easily ruptured

Phospholipid BilayerPhospholipid Bilayer

50% Lipid

50% Protein

Embedded ProteinsEmbedded ProteinsFluid Mosaic Model of Membrane StructureFluid Mosaic Model of Membrane Structure

Cytoplasm Filled with RibosomesCytoplasm Filled with RibosomesRibosomes Utilize 25% Cell’s Volume – 90% Cell’s

Energy

RibosomesRibosomes

• Composed of RNA and Protein

• Function to Make Protein (Mainly Enzymes)

• Size is Measured in Svedberg (S) units

• Bacterial Ribosomes are ~70S

NucleoidNucleoid

Plasmids are small circular DNA elements found in virtually all bacterial cells.

They carry extra genes and are important in Genetic Engineering.

Inclusion Bodies or Storage Inclusion Bodies or Storage GranulesGranules

• Fats• Sugars• Phosphates• Sulfur• Metachromatic

Granules

Prokaryotic bacteria exist in very competitive environments where nutrients are usually in short supply, so they tend to store up extra nutrients when possible.

EndosporesEndospores

Survival Mechanism for Extended Periods in the Absence of Food, Water, of Proper Growth Conditions

EndosporesEndospores

• Can resist Sterilization• Can resist Boiling• Can resist UV Light• Can resist Dessication• Can resist Harmful Chemicals• Abundant in Bacillus and Clostridia• Germination in Minutes• Create a Problem with Canned Foods

We worry about

canned goods and botulism.

Oval Terminal

Rectangular Terminal

Rectangular Subterminal

Rectangular Central

Circular Terminal

Circular Central

Club Shaped Terminal

BacteriaEndospores

Schaeffer Fulton Method of Staining

Dorner Method of Staining

Dating EndosporesDating Endospores

• Spores taken from prehistoric mosquitoes suspended in Amber

• Roman Fort Vindolanda- 1976 Fort dating AD 90-95 was drained and excavated

- Found viable endospores of Thermoactinomyces vulgaris - Thermophilic Aerobic Bacterium (Warmth and Moisture)- Had been sealed in a cold anaerobic environment (flooded)- Would date this particular endospore to being 2000 years

old

Eukaryotic Cells

CiliaCilia

Chromosomes and ChromatinChromosomes and Chromatin

Nucleus with Double Nucleus with Double MembraneMembrane

MitochondriaMitochondria

Endosymbiotic Theory of Cellular Endosymbiotic Theory of Cellular EvolutionEvolution

• Proposed by Lynn Margulis in 1981

• Studied Mitochondria

• Saw association between Mitochondria and Gram-negative Bacteria

Endomembrane SystemEndomembrane System

• Endoplasmic Reticulum

• Golgi Apparatus• Various Vesicles• Lysosomes• Microbodies• Nuclear Membrane

Rough E.R.

Functions InFunctions In

• Compartmentalization• Chemical Homeostasis• Communication• Transport

Golgi Apparatus

Membrane TransportMembrane Transport | |

Small Molecules Large Molecules

| | | |

Passive Transport Active Transport Endocytosis Exocytosis

| |

Diffusion Phagocytosis

Osmosis Pinocytosis

Facilitated Diffusion

ExocytosisExocytosis

EndocytosisEndocytosis

Phagocytosis in Action

Endosymbiotic Theory / Endosymbiotic Theory / EukaryotesEukaryotes

• The endosymbiotic theory concerns the mitochondria, chloroplasts, and possibly other organelles of eukaryotic cells.

• According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts.

• Mitochondria developed from proteobacteria such as Rickettsiales, and chloroplasts from cyanobacteria.