Diversity of Organisms unit 2

Classification of organisms

Scientists organize living things so we can identify and study them .

Created by Carl Woese

3 Domain system (1978)

It groups organisms based on evolutionary relationships .

Scientists compare things like:

• rRNA

• ribosomes

• lipids

• tRNA

• cell structures

• fossils

The Classification Levels -From biggest group → smallest group:

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

“ Dear King Philip Came Over For Good Soup.”

species

only level containing living organisms

Linnaeus

binomial system of nomenclature
each organism has a genus and species name

Each organism has two names :

• Genus

• Species

Example: E. coli

📌 Catchy phrase

“ Every organism gets a first name and a last name.”

Domain Bacteria-note

typical bacteria; many pathogens
prokaryotic cells (no nucleus) with peptidoglycan external cell walls
more than 3000 recognized species- most bacteria in nature unknown

1⃣ Domain Bacteria

Typical bacteria.

Characteristics:

• Prokaryotic cells ( no nucleus)

• Cell wall contains peptidoglycan

• Many cause disease

📌 Catchy phrase

“ Bacteria = basic bacteria.”

Domain Archaea

ancient bacteria; Archaebacteria
more than 100 species- no known human pathogens; some normal flora
prokaryotic cells (no nucleus) without peptidoglycan in the external cell walls
also characterized by unusual metabolism, branched phospholipids

2⃣ Domain Archaea

Ancient bacteria.

Characteristics:

• Prokaryotic

• NO peptidoglycan

• Strange metabolism

• Live in extreme environments

📌 Important:

• No known human pathogens

📌 Catchy phrase

“ Archaea are the ancient survivors.”

Domain Eukarya

Organisms with nuclei .

all eukaryotic with nuclei

Includes kingdoms like:

• Fungi

• Plants

• Animals

📌 Catchy phrase

“ Eukarya = cells with a nucleus headquarters.”

Kingdom Protista

no longer recognized
single celled- animal, plant, fungi; some parasitic

Viruses ⚠

Viruses are NOT considered living .

Why?

• Cannot reproduce alone

• Need a host cell

📌 Catchy phrase

“ Viruses are parasites, not people.”

Kingdom Fungi

multicellular fungi; saprophytic; some parasitic

Kingdom Plantae

multicellular plants- photosynthetic; no parasites

Kingdom Animalia

multicellular animals- all heterotrophic; few parasitic

excludes viruses

not considered to be living
cannot reproduce without a host- all parasitic on something

Where Did Eukaryotic Cells Come From?

Scientists think eukaryotes evolved from prokaryotes .

probably derived from prokaryotes; no direct evidence for transition
some chemical, other evidence for nucleus, organelle formation

nuclear membrane, ER

may have formed from infolded cell membranes

Nitrobacter

living form with highly infolded cell membrane

endosymbiotic theory

describes origin of mitochondria and chloroplasts

A large cell engulfed smaller bacteria that started living together.

Those bacteria became:

• Mitochondria

• Chloroplasts

endosymbiotic theory-Evidence

• Have circular DNA

• Have two membranes

• Divide like bacteria

• Have their own ribosomes

📌 Catchy phrase

“ Cells swallowed helpers that stayed forever.”

evidence for endosymbiosis-note

• both mitochondria and chloroplasts are similar to prokaryotes
  

• both are surrounded by 2 membranes
  

• both have circular DNA similar to prokaryotes
  

• make some of own RNA, ribosomes, proteins, enzymes
  

• divide independently of nucleus by binary fission
  some free living bacteria similar to mitochondria and chloroplast

cyanobacteria

chloroplast like

Rickettsia

mitochondria like

Cyanophora

requires symbiotic cyanobacteria to survive

requires symbiotic cyanobacteria to survive

Created by David H. Bergey

Used in labs to identify bacteria.

Scientists look at:

• Cell wall type

• Shape

• Oxygen needs

• Metabolism

📌 Catchy phrase

“ Bergey's book = bacteria detective guide.”

David H. Bergey; 1923; 1st ed

Lab identification techniques

Includes Chlamydia and Rickettsia

these bacteria are:

• Obligate intracellular parasites

• Must live inside host cells

obligate, intracellular parasites

grow, reproduce inside vesicles of host cell
no peptidoglycan external cell wall
outer membrane and cell membrane structurally similar to Gram negative

energy parasites

cannot produce own ATP
cannot be cultivated outside living host cell

2 phases to life cycle

elementary bodies, reticulate bodies

elementary bodies

infective stage
endocytosed and phagocytized but not killed
elementary body prevents fusion with lysosomes
stimulates infected cells to release cytokines
causes inflammation, tissue damage, scarring
elementary bodies develop into reticulate bodies inside phagocytes/ tissue cells

Chlamydia Life Cycle

Two stages:

1⃣ Elementary Body

• Infective stage

• Enters host cell

📌 Catchy phrase

“ Elementary = Enter the cell.”

---

2⃣ Reticulate Body

• Reproductive stage

• Bacteria multiply

📌 Catchy phrase

“ Reticulate = Reproduce.”

Life Cycle Summary

1⃣ Elementary body infects cell
2⃣ Turns into reticulate body
3⃣ Reproduces
4⃣ Turns back into elementary bodies
5⃣ Cell bursts and releases bacteria

📌 Catchy phrase

“ Enter → Play → Explode.”

Chlamydia trachomatis

Very common STD.

Important facts:

• ~ 100 million new cases worldwide each year

• Spread by:

  • sexual contact

  • birth from mother to baby

Many people have no symptoms .

📌 Catchy phrase

“ Silent infection but serious damage.”

Pelvic Inflammatory Disease ( PID)

Infection of:

• cervix

• uterus

• fallopian tubes

• ovaries

Can cause:

• infertility

• ectopic pregnancy

📌 Catchy phrase

“ PID scars the tubes.”

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Trachoma ( Eye Infection)

Causes chronic conjunctivitis and blindness.

Spread by:

• dirty hands

• towels

• flies

• crowded areas

Treatment strategy SAFE :

S – Surgery
A – Antibiotics
F – Facial cleanliness
E – Environmental improvement

📌 Catchy phrase

“ SAFE keeps eyes safe.”

Rickettsia

Spread by arthropods :

• ticks

• lice

• mites

Infects blood vessels → causes rash.

Example disease:

• Rocky Mountain spotted fever

📌 Catchy phrase

“ Rickettsia rides with ticks.”

Includes Streptomyces

Important because they produce many antibiotics .

Examples:

• tetracycline

• erythromycin

• streptomycin

📌 Catchy phrase

“ Streptomyces = antibiotic factory.”

1⃣ Obligate Intracellular Parasites

What it means

• They must live inside a host cell to survive .

• They grow inside small bubbles ( vesicles) inside the cell.

Think of them like bacteria that hide inside cells .

📌 Catchy phrase

“ No cell, no survival.”

2⃣ No Peptidoglycan Cell Wall

Most bacteria have peptidoglycan in their cell wall.

But these bacteria do NOT have it .

However, their membrane still looks like Gram- negative bacteria .

📌 What this means

• They stain like Gram- negative bacteria

• But their cell wall structure is different

📌 Catchy phrase

“ Looks Gram- negative, but built different.”

3⃣ Energy Parasites

These bacteria cannot make their own ATP .

ATP = the energy molecule cells use.

So they steal energy from the host cell .

📌 Catchy phrase

“ They steal the cell's battery.”

4⃣ Cannot Be Grown in a Lab Dish

Most bacteria can grow on agar plates .

But these cannot grow outside living cells .

Scientists must grow them inside living cells in the lab.

📌 Catchy phrase

“ No host cell = no growth.”

5⃣ Two Stages of the Life Cycle

These bacteria change between two forms .

Stage 1: Elementary Body

This is the infectious form .

What happens:

1. It enters the body

2. A host cell swallows it ( endocytosis)

3. Normally bacteria would be destroyed

4. But this one survives

It blocks lysosomes from killing it.

📌 What are lysosomes ?

They are the cell's garbage disposal that destroys bacteria.

📌 Catchy phrase

“ Elementary = Enter the cell.”

What Happens Next

The infected cell releases cytokines .

Cytokines = signals that call the immune system .

This causes:

• inflammation

• tissue damage

• scarring

📌 Catchy phrase

“ Immune response causes the damage.”

Stage 2: Reticulate Body

Inside the cell the elementary body changes into a reticulate body .

This stage reproduces .

So it:

1. multiples

2. turns back into elementary bodies

Eventually the cell bursts ( lysis) .

Then the bacteria spread to new cells .

📌 Catchy phrase

“ Enter → Multiply → Burst → Spread.”

Chlamydia Species That Infect Humans

Three species cause disease.

The most important is Chlamydia trachomatis

Chlamydia trachomatis ( Most Important)

Facts:

• Humans are the only reservoir ( host)

• About 100 million cases per year worldwide

• Very common sexually transmitted infection

It spreads by:

• sexual contact

• direct contact

• birth from mother to baby

📌 Catchy phrase

“ Common, silent, and spreads easily.”

How chlamydia Enters the Body

The bacteria enter through tiny cuts or abrasions in tissue.

They prefer columnar epithelial cells .

What that means

These are special lining cells found in places like:

• cervix

• urethra

• reproductive tract

📌 Catchy phrase

“ Chlamydia loves lining cells.”

Another Species: C. psittaci

Chlamydia psittaci

This one is often spread from birds .

Example:

• poultry workers

• bird exposure

• “ Bird bacteria that can infect humans.”

NGU serotype

nongonococcal urethritis; not from Neisseria gonorrhea
most common cause of sexually transmitted urethritis
leading cause of pelvic inflammatory disease (PID

PID

infection of cervix, uterus, fallopian tubes, ovaries
no normal flora above vagina
bacteria introduced by sex, tampons

chronic PID

less noticeable

acute PID

painful; seek help

life threatening

infertility due to damage from inflammatory response
chronic infections or repeated infections scar lumen of fallopian tube
can cause ectopic pregnancy in fallopian tube

can rupture tube @ 12 weeks

implant in abdominal cavity; like tumor

NGU-Nongonococcal Urethritis)

means urethritis that is NOT caused by Neisseria gonorrhoeae .

Urethritisinflammation of the urethra (the tube urine leaves from).

The mostcommon cause isChlamydia trachomatis .

📌 Simple meaning

You have irritation or infection in the urine tube,But it's not gonorrhea .

📌 Catchy phrase

“ NGU = urethritis that isn't gonorrhea.”

Most Common STD Cause of Urethritis

NGU is the most common sexually transmitted cause of urethritis .

That means many people with urethra infections actually have chlamydia , not gonorrhea.

📌 Catchy phrase

“ Most urethritis = Chlamydia.”

Pelvic Inflammatory Disease ( PID)

NGU infections can spread upward and cause Pelvic Inflammatory Disease ( PID).

PID is infection of the:

• cervix

• uterus

• fallopian tubes

• ovaries

📌 Simple meaning

The infection moves up into the reproductive organs .

📌 Catchy phrase

“ PID = infection spreading upward.”

---

Why Infection Spreads Easily

Normally there are no bacteria above the vagina .

So when bacteria enter, the body is not used to fighting them there .

Bacteria can be introduced by:

• sexual activity

• tampons

• other objects entering the vagina

📌 Catchy phrase

“ Above the vagina should be sterile.”

Acute PID

• happens suddenly

• very painful

• people usually seek medical help

“ Acute hurts

Chronic PID

• mild symptoms

• harder to notice

• infection continues for a long time

chronic hides.

Why PID Is Dangerous

The body fights infection using inflammation .

Inflammation can damage tissues.

This damage can cause scarring in the fallopian tubes .

📌 Catchy phrase

“ The immune response causes the damage.”

Infertility

If the fallopian tubes become scarred:

• eggs cannot travel to the uterus

• pregnancy becomes difficult or impossible

📌 Catchy phrase

“ Scarred tubes = blocked pregnancy.”

Ectopic Pregnancy

Sometimes the fertilized egg gets stuck in the fallopian tube .

This is called Ectopic Pregnancy .

The embryo grows in the tube instead of the uterus.

This is very dangerous .

The tube can rupture around 12 weeks , causing severe internal bleeding.

📌 Catchy phrase

“ Ectopic = pregnancy in the wrong place.”

Infection Rates

About 5– 10% of men and women in the U.S. are infected .

The highest risk group is:

• sexually active women under 25

Doctors recommend testing after each new partner .

📌 Catchy phrase

“ Young and sexually active = highest risk.”

Symptoms

Many people do not know they are infected .

Women

About 75% have no symptoms .

more than with gonorrhea

This means the infection can spread without being noticed .

📌 Catchy phrase

“ Chlamydia is the silent infection.”

Men symptons

About 40% have symptoms .

Common symptoms:

• urethritis

• painful urination

• pus discharge

Still, many men have no symptoms .

more asymptomatic men than for gonorrhea

📌 Catchy phrase

“ Symptoms are common, but silence is common too.”

chronic conjunctivitis

trachoma serotype

Trachoma ( Eye Infection)

is caused by a type of Chlamydia trachomatis .

It causes chronic conjunctivitis , which means long -term eye infection and inflammation .

📌 Simple meaning

The inside of the eyelid becomes infected and irritated for a long time.

📌 Catchy phrase

“ Trachoma = long- term eye infection.”

Why Trachoma Is Important

is the most common preventable cause of blindness in the world .

That means people lose vision even though the disease could be prevented .

📌 Catchy phrase

“ Preventable blindness.”

Neglected Tropical Disease

Trachoma is part of the …..

These diseases:

• mostly affect poor regions

• don't get much funding or attention

• don't always cause high death rates

📌 What “ disease of poverty” means

It spreads more in places with:

• poor sanitation

• limited clean water

• crowded living conditions

📌 Catchy phrase

“ Poverty helps the infection spread.”

How Common Is​ Trachoma

Around:

• 50 million people infected

• 8+ million people have vision problems

In the United States, it is very rare now .

📌 Catchy phrase

“ Common globally, rare in the U.S. ”

Egyptian ophthalmia

granular conjunctivitis

Egyptian ophthalmia .

spread by dirty hands, secretions (eye, nose), fomites (towels, clothing), crowding, flies
scarring roughens inner surfaces of eyelids- damages cornea

Egyptian ophthalmia causes

Babies can be exposed during the first month of life .

This causes granular conjunctivitis , also called ….

This means the inside of the eyelid becomes bumpy and inflamed .

📌 Catchy phrase

“ Trachoma roughens the eyelid.”

How Trachoma Spreads

It spreads through contact with infected eye or nose secretions.

Common ways:

• dirty hands

• eye or nose secretions

• shared towels or clothing ( fomites)

• crowded living conditions

• flies carrying bacteria

📌 Catchy phrase

“ Hands, towels, flies spread the infection.”

Why trachea Causes Blindness

Repeated infections cause scarring inside the eyelid.

The rough scar tissue scratches the cornea ( the clear front of the eye).

Over time this damages vision .

📌 Catchy phrase

“ Scarred eyelids scratch the eye.”

SAFE Treatment Strategy-trachoma

Doctors use a global treatment plan called SAFE .

S – Surgery
Fix eyelids damaged by scarring.

A – Antibiotics
Kill the bacteria.

F – Facial cleanliness
Clean faces to stop spread.

E – Environmental improvement
Better sanitation and education.

📌 Catchy phrase

“ SAFE keeps eyes safe.”

Rickettsia

These bacteria are spread by arthropods .

Arthropods include:

• ticks

• lice

• mites

📌 Catchy phrase

“ Rickettsia rides with insects.”

What Rickettsia Does in the Body

The bacteria infect phagocytes ( immune cells).

They then damage blood vessels .

This causes:

• rash

• circulation problems

📌 Catchy phrase

“ Rickettsia attacks blood vessels.”

Why It Can Be Fatal-Rickettsia

fatal due to vascular collapse

The infection damages blood vessels so badly that circulation can collapse .

This is called vascular collapse .

Important:
The bacteria do not produce toxins .

Damage comes from infection of blood vessels .

📌 Catchy phrase

“ Blood vessel damage causes the danger.”

Rocky Mountain Spotted Fever -Important Diseases

rodent, dog reservoir

Caused by Rickettsia rickettsii .

Spread by ticks.

rodent, dog reservoir

Animals like rodents and dogs act as reservoirs ( they carry the bacteria).

📌 Catchy phrase

“ Tick bite → spotted fever.”

epidemic typhus-Rickettsia

human reservoir

Epidemic Typhus is…

Caused by Rickettsia

Spread by lice .

Humans are the main reservoir.

📌 Catchy phrase

“ Lice spread typhus.”

Streptomyces and related groups

prokaryotic with fungus like characteristics
produce many antibiotics currently in use
tetracycline, erythromycin, streptomycin