chapter 14 lecture outline domain (kingdom) bacteria, domain (kingdom) archaea, and viruses...

Chapter 14

Lecture Outline

Domain (Kingdom) Bacteria, Domain

(Kingdom) Archaea, and

Viruses

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Outline Introduction

Features of Kingdoms (Domains) Bacteria and Archaea

Domain Bacteria (Kingdom Bacteria) – The True Bacteria

Human Relevance of the Unpigmented Purple, and Green Sulfur Bacteria

Class Cyanobacteriae – The Cyanobacteria (Blue-Green Bacteria)

Class Prochlorobacteriae – The Prochlorobacteria

Kingdom Archaea (Domain Archaea) – The Archaebacteria

Viruses

Viroids and Prions

Introduction

Fossils of bacteria - 3.5 billion years old

Fossils of first eukaryotic cells - 1.3 billion years old

Bacteria found in astronomical numbers today.

• Approximately 10 million to 1 billion– Much debate as to method of classification


All have prokaryotic cells.

• No nuclear envelopes

• Have long circular strand of DNA, ribosomes, membranes and plasmids

• No membrane-bound organelles, such as plastids, mitochondria, dictyosomes, endoplasmic reticulum

Section of Prochloron cell


Nutrition:• Primarily by absorption of food in solution through

cell wall• Some by chemical reactions or by photosynthesis

Reproduction predominately asexual, by fission.• Fission - No mitosis, DNA strand duplicates and is

distributed to new cells.

No sexual reproduction• Genetic recombination facilitated by pili or by close

contact of cells.


Cellular Detail and Reproduction of Bacteria Folds of plasma and other membranes

perform some of functions of organelles in eukaryotic cells.

Ribosomes present, but about half the size as those of eukaryotic cells.

Nucleoid - Single chromosome in form of ring

30 or 40 plasmids may be present.• Plasmids - Small circular DNA molecules that

replicate independently of chromosome

• Entire complement of plasmids consists of multiple copies of one or few different DNA molecules.


Cellular Detail and Reproduction of Bacteria Mitosis does not occur. Fission:

• The two copies of duplicated chromosomes migrate to opposite ends of cell.

• Perpendicular walls and cell membranes formed in middle of cell.

• The 2 new cells separate and enlarge to original size.

Replication of nucleoid

Fission:• May undergo fission every 10 - 20 minutes under

ideal conditions– Usually exhaust food supplies and accumulate wastes

New wall growing inward of dividing bacterial cell


Cellular Detail and Reproduction of Bacteria

Do not produce gametes or zygotes, and do not undergo meiosis

Three Forms of Genetic Recombination:• Conjugation

– DNA transferred from donor cell to recipient cell usually through pilus (pleural: pili).

• Transformation– Living cell acquires DNA

fragments released by dead cells.

• Transduction– DNA fragments carried from

one cell to another by viruses.


Cellular Detail and Reproduction of Bacteria

Conjugation

Most bacteria less than 2 or 3 micrometers in diameter.

Occur primarily in three forms:


Size, Form, and Classification of Bacteria

CocciSpherical or

elliptical

BacilliRod-shaped or

cylindrical

SpirillaHelix or spiral

Also classified by:

• Presence of sheath around cells, of hair-like or bud-like appendages, of endospores, of pili or of flagella

• Color

• Mechanisms of movement

• Biochemical characteristics

• Reaction of cell walls to dye– Gram-negative– Gram-positive


Size, Form, and Classification of Bacteria


True bacteria have muramic acid in cell walls, and are different from archaebacteria in their RNA bases, metabolism and lipids.

Phylum Bacteriophyta

• Class Bacteriae - Unpigmented, purple, and green sulfur bacteria– Most heterotrophic - Cannot synthesize own food

o Majority saprobes - Food from nonliving organic matter« Responsible for decay and recycling of organic

matter in soilo Some parasites - Depend on living organisms for food


Phylum Bacteriophyta

• Autotrophic bacteria - Synthesize organic compounds from simple inorganic substances– Photosynthetic without producing oxygen

o Purple sulfur bacteria - Bacteriochlorophyll pigments, use hydrogen sulfide

o Purple nonsulfur bacteria - Bacteriochlorophyll pigments, use hydrogen

o Green sulfur bacteria - Chlorobium chlorophyll pigments, use hydrogen sulfide

– Photosynthetic and produce oxygen - Cyanobacteria and chloroxybacteria


Phylum Bacteriophyta• Autotrophic bacteria

– Chemotrophic bacteria - Obtain energy from various compounds or elements through oxidationo Iron bacteria - Transform soluble iron to insoluble o Sulfur bacteria - Convert hydrogen sulfide gas to

sulfur or sulfur to sulfateo Hydrogen bacteria - Use molecular hydrogen derived

from anaerobic or nitrogen-fixing bacteria

Human Relevance of the Unpigmented, Purple, and Green Sulfur Bacteria

Composting and compost:• Bacteria decompose organic waste to form compost.

• Modes of access of disease bacteria:– Access from the air

o Coughs, sneezes - Saliva droplets contain bacteria.o Diphtheria, whooping cough, some meningitis forms,

pneumonia, strep throat, tuberculosis

True bacteria and disease:• Bacteria involved in

diseases of plants, animals and humans, and in losses of food


True bacteria and disease:• Modes of access of disease bacteria:

– Access through contamination of food and drinko Food poisoning and diseases associated with natural

disasters« Cholera, dysentery, Staphylococcus and

Salmonella food poisoningo Legionnaire diseaseo Botulismo Escherichia coli


True bacteria and disease:• Modes of access of disease bacteria:

– Access through direct contact - Enter through skin or mucus membraneso Syphilis, Gonorrhea, Chlamydia, anthrax, brucellosis

– Access through woundso Tetanus and gas gangrene

– Access through bites of insects and other organismso Bubonic plague, tularemia, rickettsias, mycoplasmas,

Lyme disease


Koch’s postulates - Rules for proving a particular microorganism is cause of a particular disease• Microorganism must be present in all cases of

disease.

• Microorganism must be isolated from victim in pure culture.

• Microorganisms from pure culture must be able to infect hosts.

• Microorganism must be isolated from experimentally-infected host and grown in pure culture for comparison with original culture.


True bacteria useful to humans:• Biological control organisms

– Bacillus thuringiensis - Effective against caterpillars and worms

o Multiplies in digestive tract and paralyzes gut

– Bacillus popilliae - Effective against Japanese beetle grubs

• Bioremediation - Use of living organisms in cleanup of toxic waste and pollution

Affect of Bacillus thuringiensis on tomato hornworm


True bacteria useful to humans:• Other useful bacteria

– Human health - Lactobacillus acidophiluso Aids in digestiono Used for elimination of yeast infections

– Dairy - Buttermilk, sour cream, yogurt, cheese

– Industrial - Utilizes bacteria waste products

o Solvents, explosives, ascorbic acid (vitamin C), citric acid


Distinctions between traditional bacteria and cyanobacteria:

• Cyanobacteria have chlorophyll a and oxygen is produced from photosynthesis.

• Cyanobacteria contain phycobilins.

• Cyanobacteria can both fix nitrogen and produce oxygen.


• Fresh and marine water, but not acidic water– Principal photosynthetic organisms in

plankton

• Waters of various temperatures - Hot springs at Yellowstone National Park

• Often first photosynthetic organisms after volcanic eruption

• Symbiotic with other organisms

Distribution - In diverse variety of habitats• Pools and ditches, particularly if polluted

– Amoebae, sea anemones, fungi (producing lichens), cycads

Yellowstone


Form, metabolism, and reproduction:

• Often in chains, or colonies held together by gelatinous sheaths

• Cells blue-green in color in about half of the approximately 1,500 species.

• Produce nitrogenous food reserve - Cyanophycin

• Flagella unknown


Form, metabolism, and reproduction:• New cells by fission, or by

fragmentation of colonies or filaments.

• In Nostoc and Anabaena, fragmentation often occurs at heterocyst.– Heterocyst - Large colorless,

nitrogen-fixing cell– Also produce akinetes

o Akinetes - Thick-walled cells that resist adverse conditions


Cyanobacteria, chloroplasts, and oxygen• Thought that chloroplasts originated as cyanobacteria or

prochlorobacteria living within other cells.

• Fossils of cyanobacteria, 3.5 billion years old, found in Australia.

• 3 billion years ago, cyanobacteria produced oxygen as by-product of photosynthesis.

• Oxygen accumulated in atmosphere, becoming substantial 1 billion years ago.

• As oxygen accumulated, other photosynthetic organisms appeared and forms of aerobic respiration developed.

• In last half billion years enough ozone for UV shield and for photosynthetic organisms to survive on land.


Human relevance of the cyanobacteria:

• Cyanobacteria are among the many aquatic and photosynthetic organisms at the bottom of various food chains.

• Often become abundant in bodies of fresh water in warmer months– Algal blooms

o Can be poisonous to livestock

• Food - Spirulina with significant vitamin content

• Swimmers itch

• Nitrogen fixation


Have chlorophylls a and b of higher plants, but no phycobilin accessory pigments like cyanobacteria• Adds to theory that

chloroplasts originated from cells living within cells of other organisms

Cell structure and chemistry similar to those of cyanobacteria and other true bacteria.

Prochloron


Metabolism is fundamentally different from other lines of bacteria.

Differ from true bacteria by unique sequences of bases in RNA, by lack of muramic acid in walls, and by production of distinct lipids

Methane bacteria• Killed by oxygen

• Active only under anaerobic conditions– Energy derived from generation of methane gas from

carbon dioxide and hydrogen.


Salt bacteria

• Metabolism enables these bacteria to thrive under extreme salinity.– Carry out simple

photosynthesis with aid of bacterial rhodopsin.

Lake Bonneville, Utah with very high salt content


Sulfolobus bacteria

• Occur in sulfur hot springs

• Metabolism allows these species to thrive at very high temperatures.– Mostly in vicinity of 80oC (170oF), some even higher

• Shape of ribosomes and chemistry of sulfolobus bacteria distinguishes them from other archaebacteria, true bacteria and eukaryotes.


Human relevance of the archaebacteria:

• Methane bacteria produce methane gas as they digest organic wastes in absence of oxygen.– Methane may be used to furnish energy for engines,

heating and cooking.

– Methane has a high octane level and is clean and nonpolluting.

– Methane produced on large-scale when organic wastes fed into methane digester.o Leftover sludge makes excellent fertilizer.

Viruses Size and structure:

• Represent interface between biochemistry and life– Lack cytoplasm or cellular structure

o Do not grow by increasing in size or dividing

o Do not respond to external stimuli

o Cannot move on their owno Cannot carry on independent

metabolism o Inside living cells, they

express their genes and use cellular machinery to produce more virus particles.

– About size of large molecules, 15-300 nanometers

Papavoviruses in a human wart

Viruses Size and structure:

• Consist of nucleic acid core surrounded by protein coat.

• Architecture of protein coat varies.– 20-sided, or head and tail

• Core consists of DNA or RNA, not both.

• Classified according to DNA or RNA.– Then according to size and

shape, nature of protein coats, and number of identical structural units in their cores.

• Bacteriophages - Viruses that attack bacteria

Viruses Viral reproduction:

• Viruses replicate at expense of their host cells.– Attach to susceptible cell– Penetrate to cell interior– DNA or RNA dictates

synthesis of new molecules.– New viruses released from

host cell.o Host cell dies.

– Some can mutate very rapidly.o As a result, new vaccines

need to be developed. Bacteriophage replication

Viruses Human relevance of viruses:

• Annual loss in work time due to common cold and influenza viruses alone amount to millions of hours.– Immunizations have dramatically decreased incidence of

many viral diseases such as chicken pox, German measles, and mumps.

• AIDS– Retrovirus - A virus with two identical nuclear strands

o Evolves extremely quickly« About a million times faster than cellular organisms

• Used to infect disease organisms of animals and plants– Ticks, insects, possibly gypsy moths

Viroids and Prions Viroids - Circular strands of RNA that occur

in nuclei of infected plant cells

• Transmitted from plant to plant via pollen, ovules, or machinery– Cause more than a dozen plant diseases

Prions - Appear to be particles of protein that cause diseases of animals and humans

• Believed to cause disease by inducing abnormal folding of proteins in brain, resulting in brain damage– Cruetzfeldt-Jacob disease

Review Introduction



Human Relevance of the Unpigmented Purple, and Green Sulfur Bacteria




Viruses

Viroids and Prions

chapter 14 lecture outline domain (kingdom) bacteria, domain (kingdom) archaea, and viruses...

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