MODULE #2: Kingdom Monera

Prokaryota (pro kehr ee aht' uh)

The general name bacteria (singular is

bacterium) can essentially be applied

to all of the organisms

in kingdom Monera.

Pathogen – An organism that

causes disease

3 Basic Shapes of Bacteria

These are false-color images.

Typical Bacterium

All are prokaryotic; not all contain every organelle

Typical Bacterium

capsule – organic layer of sticky sugars

Typical Bacterium

cell wall - 3 purposes:

cell wall -

1. holds the contents of the

bacterium together,

2. regulates the amount of water

that a bacterium can absorb, and

3. holds the cell into one of three

basic shapes

Typical Bacterium

plasma membrane - Made of phospholipids

and proteins.

The plasma membrane – regulates

what the bacterium takes in from the

outside world.

1. protects the interior of the cell by

sensing the nature of the chemicals

in the surroundings and then

determining whether or not they

can enter the cell.

The plasma membrane – regulates

what the bacterium takes in from the

outside world.

2. In some cases, if the cell needs the

chemicals, the plasma membrane

will actually force the chemicals into

the cell, whether they “want” to

come in or not!

Typical Bacterium

Cytoplasm exists throughout the interior of the

cell, supporting the DNA and the ribosomes .

Cytoplasm exists throughout the interior of the cell, supporting the and the (rye' b

DNA holds all of the information required to

make this mass of chemicals a living entity.

Ribosomes are chemical factories that make

proteins,

Positioned throughout the cytoplasm are

thousands of different types of chemicals

which aid the parts of the cell in their tasks.

Typical Bacterium

fimbriae - fibrous bristles used for grasping. If

in reproduction, they’re called sex pili.

Typical Bacterium

flagellum - used for motion. If a bacterium

does not possess a flagellum, it cannot move.

The flagellum – 3 Main Parts

The flagellum

The flagellum

Basal Body

Question: Two different species of bacteria

attempt to infect an organism. One bacterium

succeeds, while the other is destroyed by the

organism's infection-fighting mechanisms. What is

most likely the major difference between these

two bacteria?

Answer:

The bacterium that succeeded most likely has a

capsule while the other does not.

In bacteria, the capsule helps to protect the

organism from infection-fighting mechanisms.

Question: A bacterium is poisoned by a substance

that is allowed into the interior of the cell. What

bacterial component did not do its job?

Answer

The plasma membrane did not do its job.

Since it regulates what moves in and out of the cell,

it should not have allowed the toxin to enter.

Question: If a bacterium cannot move, what

structure is it missing?

Answer:

It is missing a flagellum.

The fimbriae are not for movement; thus, if a

bacterium has no flagellum, it cannot move.

The Eating Habits of Bacteria

Great diversity in the eating habits - there are

producers, consumers, and decomposers

in kingdom Monera.

Most are heterotrophs – rely on other organisms

for food production.

Most are decomposers – referred to as

saprophytes.

The Eating Habits of Bacteria

Saprophyte – An organism that feeds on dead

matter

The Eating Habits of Bacteria

Some bacteria are parasites.

Parasite – An organism that feeds on a living host

Many parasitic bacteria lack the ability to digest

nutrients, so they need to absorb nutrients that

have already been digested. In addition, they

often lack the ability to manufacture the complex

chemicals necessary for life. As a result, they

must also absorb those chemicals from their host.

Autotrophic Bacteria

Two different means by which autotrophic

bacteria manufacture their own food:

1.photosynthesis

2.chemosynthesis.

Photosynthesis in Bacteria

Photosynthesis uses the energy from sunlight and certain

chemicals to make food for the autotrophic organism.

In green plants and most of the other photosynthetic

organisms, the byproduct of photosynthesis is oxygen.

In bacteria, photosynthesis does not have oxygen as a

byproduct because the chemicals used are different from

those used by plants.

The byproducts of photosynthesis from bacteria are useful

to certain organisms. (Module #5).

In chemosynthesis, the bacteria promote chemical reactions

which release energy.

The bacteria then use that energy, along with other

chemicals, to manufacture their food.

Usually, the chemical reactions that provide energy to

chemosynthetic bacteria also convert chemicals that living

organisms can't use into chemicals that certain living

organisms can use.

Thus, even though there are only a few types of

chemosynthetic bacteria, they perform an essential function

for many living organisms.

Chemosynthesis in Bacteria

There must be a process by which food is converted

into energy to support life.

In humans, digestion does not give us energy. It simply

breaks food down into smaller molecules. In order to

get energy, we must then combine these molecules with

oxygen (and burn our food).

Since we use oxygen in order to get energy from our

food, humans are called aerobic organisms.

Aerobic organism – An organism that

requires oxygen

Some bacteria do not require oxygen in order to convert

their food into energy. These bacteria are anaerobic

organisms.

Anaerobic organism – An organism that does

not require oxygen

Typically, they live in areas that are barren of oxygen

such as deep underground or in the muck at the bottom of

a swamp. They either decompose dead organisms or

convert useless chemicals into chemicals that can be used

by other life forms.

Question: Can saprophytic bacteria be

autotrophic?

Answer:

No.

Saprophytic means that it feeds on dead matter.

Autotrophic organisms make their own food.

Question: Can an aerobic bacterium be

chemosynthetic?

Answer:

Yes.

Aerobic and anaerobic deal with how the organism

converts its food into useful energy.

Chemosynthetic deals with how the organism gets

the food to begin with. Thus, the bacterium can

make the food chemosynthetically and then

convert it to useable energy aerobically.

Asexual Reproduction in Bacteria

binary

fission

Asexual Reproduction in Bacteria

Asexual Reproduction in Bacteria

Asexual Reproduction in Bacteria

Asexual Reproduction in Bacteria

Asexual Reproduction in Bacteria

Speed of Reproduction & Its Repercussions

Under ideal conditions, a bacterium can divide in

about 20 minutes.

Once it divides, the new bacterium and the old

one can divide again in about 20 minutes.

One bacterium could multiply into more than a

billion bacteria in about 10 hours.

In a week, the bacteria would have a combined

weight that is larger than the entire planet!

Luckily, resources will run out eventually.

Steady state – A state in which members of a

population die as quickly as new members are

born

During the initial stage of population growth, the bacteria are reproducing

unchecked. There are plenty of resources for the population, so the population

grows as quickly as the bacteria can reproduce. This is called exponential growth.

Exponential growth – Population growth that is unhindered because

of the abundance of resources for an ever-increasing population.

When you graph a population that experiences logistic growth, you

get the S-shaped curve (often called a sigmoidal curve) that is

shown in the pink section of the graph.

As the population begins to reach the limits of the environment's resources, it can no

longer grow unchecked. The population growth is controlled by the limited resources of

the environment. This is referred to as logistic growth.

Logistic growth – Population growth that is controlled by limited resources

If you look at Figure 2.5 again, you will see that there is a region that is highlighted in

pink. That is the region over which logistic growth occurs.

Question: A population of bacteria grown from a

single “starter” bacterium is rather fragile. When

conditions are changed, the population dies

quickly. Based on what you have just learned,

develop a hypothesis for why this is the case.

Answer:

Since asexual reproduction allows no variation in

the DNA, an entire population of bacteria started

from a single bacterium have all the same traits. If

the environment changes, an organism might need

new traits to survive. Since the whole population

has essentially the same traits, there is no way to

get the needed new traits, and the population dies.

The variability that exists in sexual reproduction

usually makes a population much more resistant to

changes in the habitat.

Question: A population of bacteria reaches a

steady state and then, after several days, the

population actually increases dramatically. What

could cause such an event?

Answer:

More resources (most likely food) were added to

the habitat.

The only way you can get population

growth after the steady state would be due to an

influx of new resources.

Genetic Recombination in Bacteria

In asexual reproduction the offspring is a genetic copy

of the parent.

It is often beneficial for bacteria to exchange genetic

information in order to increase the genetic diversity of

the population.

Bacteria do this by genetic recombination, which can

occur in one of three ways:

1. conjugation,

2. transformation, or

3. transduction.

Genetic Recombination in Bacteria

Conjugation – A temporary union of two

organisms for the purpose of DNA transfer

Conjugation is not sexual reproduction.

No offspring is formed.

Genetic information is transferred from a

donor bacterium to a recipient.

Genetic Recombination in Bacteria

Desirable traits present in some individuals are contained

in a small, circular strand of DNA called a plasmid. The

plasmid is an extra component, separate from the rest of

the bacterium's DNA.

Plasmid – A small, circular section of extra

DNA that confers one or more traits to a

bacterium and can be reproduced separately

from the main bacterial genetic code

Question: A population of bacteria are living in a

lake. Due to volcanic activity nearby, the lake's

temperature begins to increase. In the population,

there are some bacteria that are resistant to low

temperatures (call them type A) and another type

that are resistant to high temperature (call them

type B). Which type will be the donor and which

the recipient as the population begins to

conjugate?

Answer:

Type B will be the donors and Type A will be the

recipients.

Since the bacteria will need to survive in high

temperatures, they need resistance to high

temperatures. That's what will be donated.

Transformation – The transfer of a DNA segment

from a nonfunctional donor cell to that of a

functional recipient cell

1. A bacterium dies

2. its cell wall falls apart and the components of the cell

(including the DNA) flow into the surroundings.

3. the dead bacterium's DNA seems to break into small

pieces,

4. a living bacterium might “sense” that one or more of

those pieces contains a trait or traits that it could use.

5. The living bacterium then absorbs what it needs,

incorporating the new genetic information as a plasmid.

Transformation

Transduction – The process in which infection

by a virus results in DNA being transferred

from one bacterium to another

A virus can pick up DNA from a bacterium during

infection and that DNA can be inserted into another

bacterium in a subsequent infection.

Transduction

Imagine a sample of water that is filled with

bacteria. You boil the water to try to kill the

bacteria. Will that get rid of the population?

Not necessarily.

Although boiling water will kill the bacteria,

they can actually survive the high

temperature for some period of time by

producing an endospore.

Endospore Formation

Endospore – The DNA and other

essential parts of a bacterium coated

with several hard layers

Endospore Formation

The endospore is formed inside the

bacterium's plasma membrane.

Once an endospore forms, the bacterium

itself might die, but as long as the endospore

survives, the bacterium can reform.

Endospore Formation

An endospore can withstand extreme

situations (boiling/freezing/extreme dryness)

for a lot longer than the bacterium itself.

When favorable conditions return, the hard

layers surrounding the DNA will deteriorate,

and the cell will burst from the endospore,

ready to grow and reproduce again.

Endospore Formation

Many bacteria exist in colonies.

• The individual bacteria group together, but

they all still exist as individuals.

• The bacteria's ability to survive is usually

enhanced when they form a colony.

Bacterial Colonies

As you might expect, bacteria form colonies in

a variety of different ways.

Bacteria take on one of three basic shapes:

coccus (spherical), bacillus (rod-shaped), or

spirillum (helical).

The most common bacterial colonies are

made up of either cocci or bacilli bacteria.

Bacterial Colonies

The shape of the bacteria is often contained in the name so you

automatically know something about the organism from just the

name.

If the bacteria are spherical, the name ends in “coccus.” If they are

rod-shaped, the name ends in “bacillus.”

You are expected to be able to determine the shape of a bacterium

when it is a part of the name.

DNA seems to tell them what colony they should

form.

Exhibit “group” behavior:

Some colonies, for example, will secrete a capsule-like

substance that surrounds and protects the entire colony.

Other colonies have bacteria that actually work together to

capture and eat prey. A Myxococcus xanthus colony, for

example, moves as a unit in search of prey, typically other

bacterial colonies. When they find their prey, they engulf it

and, as a group, secrete a substance that digests it. The

entire colony then feeds on the nutrients.

Question: A bacterial colony is called

staphylobacillus. What shape do the bacteria in the

colony possess: spherical, rod-shaped, or helical?

Answer:

They are rod-shaped

“bacillus” means rod-shaped.

Classification in Kingdom Monera

Under a Gram stain, some bacteria turn red (Gram-

positive) and others turn blue (Gram-negative).

Reaction caused by differences in the cell wall.

Classification in Kingdom Monera

Phyla

Gracilicutes (gruh' sil uh kyoo' teez) – bacteria has cell wall &

Gram-negative m .

Firmicutes (fir' muh kyoo' teez) – bacteria has cell wall &

Gram-positive .

Tenericutes (ten' uh ruh kyoo' teez) – bacteria does not have

a cell wall.

Mendosicutes (men' doh suh kyoo' teez) – bacteria has cell

wall but the compounds are different from those that form

Gram-positive or Gram-negative reactions..

Question: A bacterium has no cell wall. To what

phylum does it belong?

Tenericutes is the phylum for bacteria without a

cell wall.

Question: A bacterium is classified as Gram-

positive. To what phylum does it belong?

Answer:

Firmicutes contains all Gram-positive bacteria.

Question: A bacterium appears red after a Gram

stain. To what phylum does it belong?

Gracilicutes contains all Gram-negative bacteria.

Since the bacterium appears red after the Gram

stain, it is Gram-negative.

Question: A bacterium has a cell wall that is

different from both Gram-positive and Gram-

negative bacteria. To what phylum does it belong?

Answer:

Mendosicutes contains all bacteria with exotic cell

walls.

Class based on how bacteria obtains food.

Class based on shape.

Only 1 class.

Only 1 class.

On Test You Will Be Expected To Be Able To Classify Based On

Characteristics!

Question: Construct a biological key that separates

bacteria into their different classes. You can

assume that the only organisms the key will be

used to analyze are bacteria. (HINT: The first

question should determine whether or not the

bacterium has a cell wall.)

Answer: See Table 2.1

1. Cell wall .............................................2

No cell wall ...........................................phylum Tenericutes.......class Mollicutes

2. Gram-positive or Gram-negative.......3

Neither .................................................phylum Mendosicutes.......class Archaebacteria

3. Gram-Positive...................................phylum Firmicutes............4

Gram-Negative.....................................phylum Gracilicutes.........5

4. Bacillus or Coccus........................... .class Firmibacteria

Neither ................................................class Thallobacteria

5.Non-photosynthetic..........................class Scotobacteria

Photosynthetic.....................................6

6. Produces oxygen..............................class Oxyphotobacteria

Does not produce oxygen....................class Anoxyphotobacteria

A Few Words on Other Classification Systems

Six-kingdom system.

• Retains kingdoms Protista, Fungi, Plantae, and

Animalia,

• Splits kingdom Monera into two separate

kingdoms: Archaebacteria and Eubacteria.

Most of the organisms that we have placed in

phylum Mendosicutes, class Archaebacteria are put

into kingdom Archaebacteria,

Most of the rest are placed in kingdom Eubacteria.

Specific Bacteria

Class Archaebacteria

• Have cell walls

• Live in harsh conditions

• Anaerobic chemosynthetic bacteria belong to this class.

Blue-Green Algae (al' jee) or Cyanobacteria (sye' an oh bak tehr'ee

uh)

Look like Algae

Live in freshwater lakes and ponds and are most prevalent in stagnant

waters.

Form the blue-green mats that float on the surface of the water.

Colonies of eukaryotic cells.- living in long, thin strands of cells that

encapsulate themselves (feel slimy)

Photosynthetc – require light to survive

Specific Bacteria

Clostridium (claw strid' ee um) botulinum (bot' yool in um)

Class: Firmibacteria; Phylum: Firmicutes

Source of food poisoning Heat resistant endospores

produces a toxic chemical that causes botulism.

Salmonella (sal muh nell' uh) typhimurium (tye' fim ur ee um) and

S. enteriditis (en' ter uh dye' tus)

Same genus: Salmonella; Phylum Gracilicutes; Class Scotobacteria.

Common contaminants of eggs and poultry.

Specific Bacteria

Escherichia (esh' ur ee' kee uh) coli (koh' lye)

Phylum Gracilicutes; Class Scotobacteria.

Very common, living in your gut.

Its species name, “coli” refers to the “colon,” which

is a part of your gut.

Two Strains.

Strains – Organisms from the same species

that have markedly different traits

Specific Bacteria

• Escherichia (esh' ur ee' kee uh) coli (koh' lye)

1) Nonpathogenic

• One of the byproducts of E. coli's

metabolism is Vitamin K

• Secretes a chemical that helps your body

digest fat.

• Keeps food-borne pathogenic bacteria from

colonizing in your gut.

2) Pathogenic – causes severe diarrhea

Conditions For Bacterial Growth

Moisture

Moderate temperature: 27 °C - 38 °C (80 °F - 100 °F)

Nutrition

Darkness

The proper amount of oxygen

Preventing Bacterial Infections

Expose food to extreme heat or radiation

Dehydrate food

Prolonged freezing of food

Pasteurization