Bacteria Ch.19-1By: A. Cortez

Classifying ProkaryotesThanks to Robert Hooke and Anton van Leeuwenhoek, the invention of the microscope opened our eyes to the hidden, living world around us.

Microscopic life covers nearly every square centimeter of Earth

Classifying ProkaryotesRemember!!!!- The smallest and

most common microorganisms are Prokaryotes

They are single-celled, lack a nucleus

For many years prokaryotes were called “bacteria”

Classifying Prokaryotes

Until most recent prokaryotes were placed in the kingdom-Monera.

Now, they are divided into two kingdoms: Eubacteria and Archaebacteria

Classifying ProkaryotesRemember they

are much smaller then eukaryotic cells.

Prokaryotes range about 1 to 5 micrometers

Eukaryotes range: 10-100 micrometers in diameter.

Classifying ProkaryotesEubacteriaEubacteria is the larger of the two

kingdomsHas a wide range of organisms with

different lifestyles.They live mostly everywhere:

freshwater, land, salt water, and within the human body.

They have a cell wall that protects from injury and the cell wall contains a peptidoglycan which is a source of carbohydrate.

Classifying ProkaryotesArchaebacteriaArchaebacteria look very

similar to eubacteria under microscope.

They are both small, lack nucleus, have cell wall, but chemically archaebacteria are quite different.

Classifying ProkaryotesArchaebacteriaThey lack peptidoglycan with

eubacteria does have.Also, The DNA sequences of key

archaebacterial genes are more like those of eukaryotes.

They live in extreme environments such as: volcanos, areas of boiling point waters, the great salt lake in Utah.

Identifying ProkaryotesProkaryotes are

identified by characeristics such as shape, the chemical nature of their cell walls, the way they move, and the way they obtain energy.

Identifying ProkaryotesShapesA Rod-shaped

prokaryote is called a Bacilli

A Spherical prokaryote is called a Cocci

Spiral and corkscrew-shape is called a Spirilla

Identifying Prokaryotes

Cocci Spirilla

Identifying ProkaryotesCell WallsTwo types of

cell wallsScientist use a

method called Gram staining to tell them apart.

The gram stain consist of two dyes: violet and red.

Identifying ProkaryotesCell WallThe violet stain is applied first , which

stains peptidoglycan cell wall.Then followed by a alcohol treatment

that tends to wash out the stain.Gram Positive bacteria has thick

peptidoglycan walls that remain dark in color.

Gram Negative bacteria has a thinner walls, alcohol dissolves peptidoglycan, light color:pink, light red.

Identifying ProkaryotesMovementYou can identify

prokaryotes by where they move and how they move.

They are propelled by flagella, a whiplike structure used for movement

Identifying ProkaryotesMovementOther prokaryotes lash, snake, or spiral forward.

Also some Prokaryotes glide slowly along a layer of slimelike material they secrete

Metabolic DiversityMost prokaryotes are heterotrophs,

meaning that they obtain energy by consuming organic molecules made by other organisms.

Other prokaryotes are autotrophs and make their own food from inorganic molecules.

Two types of Heterotrophs 1. Chemoheterotrophs 2. Photoheterotrophs

Metabolic DiversityMost heterotrophic

prokaryotes must take in organic molecules for both energy and a supply of carbon, these prokaryotes are called chemoheterotrophs.

We are chemoheterotrophs ourselves

Which means prokaryotes compete directly with us for food.

Metabolic Diversity

A smaller group of heterotrophs called photoheterotrophs , use sunlight for energy, but also need organic compounds as a carbon source.

Metabolic DiversityThere are two types of autotrophs.

1. Photoautotrophs 2. ChemoautotrophsPhotoautotrophs-use light energy to convert carbon dioxide and water to carbon compounds and oxygen.

Metabolic DiversityChemoautotrophs- make

organic carbon molecules from carbon dioxide

They do not require light as a source of energy.

Instead they consume chemical reactions from ammonia, hydrogen sulfide, nitrites, sulfur, or iron.

Examples: ocean floor plants

Metabolic DiversityReleasing EnergyBacteria need a constant supply of

energy.Organisms that require a constant

supply of oxygen in order to live are called: Obligate Aerobes.

Organisms(bacteria) that do not require oxygen and, in fact may be killed by it are called: Obligate Anaerobes.

Organisms that can live with or without oxygen are called Facultative Anaerobes

Growth and Reproduction

Conjugation: Bacteria are able to exchange genetic information

A hollow bridge forms between two bacterial cells

Growth and ReproductionBinary Fission:

When a bacterium has grown so that it has nearly doubled in size, it replicates its DNA and divides in half, producing two identical “daughter” cells.

Growth and ReproductionSpore formation:

when growth conditions become unfavorable, many bacteria form structures called spores.

One type of spore is called endospore

A thick internal wall that encloses its DNA and a portion of its cytoplasm.

Importance of BacteriaBacteria are vital to maintaining the living world.

Some are producers that capture energy by photosynthesis.

Others are decomposers, which break down the nutrients in dead matter and the atmosphere.

Importance of BacteriaDecomposersBacteria help the

ecosystem recycle nutrients. Maintaining equilibrium

Ex. When a tree dies, bacteria attacks and digests the dead tissue. Breaking it down into simpler tissue, which are released into the soil.

Importance of BacteriaQuick reminder !!!!!That Nitrogen (N), gas makes up

approximately 80 percent of Earth’s atmosphere.

Plants need nitrogen to make amino acids, the building blocks of proteins.

However, plants cannot use nitrogen gas directly……………

Importance of BacteriaNitrogen must be changed

chemically to ammonia (NH3) or other nitrogen compounds.

This process of converting nitrogen gas into a form plants can use is known as Nitrogen Fixation.

Human Uses of BacteriaBacteria provides us with

products we depend on every day.

1. Production of a wide variety of foods and beverages.

2. Digest petroleum to clean oil spills

3. Removal of poison from water.4. Humans benefit from E.coli , by

it making a number of vitamans that body cannot itself.