Bacteria KingdomsEubacteria & Archaebacteria

October 15 & 17, 2019Pre-AP Biology

The most common microscopic organisms on Earth are the Prokaryotes

� Prokaryotes are single-celled organisms that lack a nucleus

� They are most commonly known as bacteria

� Range in size from one to five micrometers

� All bacteria used to be classified in a kingdom called Monera

� Now they are classified into two kingdoms called Eubacteria and Archaebacteria

Prokaryotes were the first groups of life to evolve on Earth.

� Prokaryotes have relatively small, simple cells.

� For the first billion years,they were the only life on planet Earth!

� Today, prokaryotes arefound everywhere there is life, including many places where no other life can survive.

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Typical Structure of Prokaryotes(Draw & Label)

Cell wall Cell membrane Ribosome

Pili DNAFlagellum

In a prokaryotic cell, the DNA floats in the cytoplasm as a single circular molecule (chromosome)

DNA molecule is a very long molecule

The DNA in a bacteria cell is about 1000 times longer than the bacteria itself!

Prokaryotes exhibit a wide range ofshapes & structures.

Cocci are cells with a spherical shape that maybe found alone,in chains, or clustered.

Bacilli are rod-shaped cells that may be found singly or in chains.

Spiral or curved shaped prokaryotes mostly occur singly.

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Bacteria Shapes

bacilli

cocci

spirilla

Escherichia coli

streptococcus

Sludge bacteria

Include a drawing of each type of bacteria in your Sketch Notes J

In favorable conditions the growth and division of bacteria can be very rapid

One form of bacterial reproduction is called binary fission

This is asexual reproduction (mitosis) to produce two identical daughter cells

Replicated DNA

Conjugation is a form of sexual reproduction that involves an exchange of genetic material between one cell and another

This transfer of genetic material increases genetic diversity in populations of bacteria

Spore formation in bacteria is a form of adaptation

Some bacteria produce thick walls around their DNA called an endospore during unfavorable conditionsWhen conditions improve, the endospore germinates and the

bacteria grows again

Movement

�Bacteria move by either flagellastructures, spiraling them forward

�Or by gliding along slime-like secretions

�Some bacteria have no movement at all

Obtaining Energy

� When it comes to obtaining energy, prokaryotes are very diverse

� Most bacteria are heterotrophs that eat organic matter

� Some bacteria can photosynthesize, such as cyanobacteria

� If enough of a bacteria is eating your food before you do, it may cause food poisoning

Two of the six kingdoms of life consist of prokaryotes: Eubacteria and Archaebacteria.

Eubacteria• Unicellular• Found everywhere• Some cause disease,

but most are beneficial

Archaebacteria• Unicellular• Often live in extreme

conditions

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Methanogens live in oxygen-free (anaerobic) environments.

� Methanogens emit methane gas as a waste product of their metabolism.

� They are frequently found in the thick mud at the bottom of a swamp or bog.

Methanogens thrive in the oxygen-free conditionswithin landfills.

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Halophiles thrive in salty environments.

� Many species of halophiles can tolerate salt concentrations 5 to 10 times higher than that of seawater.

Dead Sea, Israel

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Thermophiles tolerate high-temperature environments.

� Thermophiles (“heat lovers”) can live in areas with temperatures above boiling.

� Conditions may be similar to those faced by the first organisms billions of years ago.

The Grand Prismatic Spring, Yellowstone National ParkChapter Table of Contents© 2017 Pearson Education,

Inc.

Fossilized Bacteria from Meteorites