1. Chapter 12.1 The Prokaryotes: Kingdom Archae and Bacteria

2. What are Bacteria?
“Bacteria” - describes organisms that belong to Kingdom Archaebacteria and Eubacteria.
singular - bacterium
Kingdom Archaebacteria
Oldest group of organisms on Earth
live only in extreme environments
Kingdom Eubacteria
typically think of as
“true bacteria”

3. Structure of Bacteria DNA Plasmid Cell Wall
1 single chromosome
Contains the genetic information
Plasmid
Smaller ring of DNA containing fewer
genes than chromosome
Cell Wall
-Provides structure and protection
Flagella (singular: flagellum)
- Whiplike structure for MOVEMENT
-stems from cell wall and cell membrane

4. Prokaryotes vs. Eukaryotes
DNA floats freely in cytoplasm
No nucleus
No membrane-bound organelles
Eukaryotes:
DNA enclosed in nucleus
Membrane-bound organelles present
For example: chloroplast, mitochondria
10 times larger in size compared to
prokaryotes

5. Bacteria Characteristics:
Live almost EVERYWHERE!
Microscopic – vary between 1-10μm
Single-celled organisms = unicellular
All bacteria are prokaryotes:
DNA is not contained in a nucleus and do not have membrane-bound cell organelles
DNA is made up of 1 single chromosome in the shape of a ring
All bacteria reproduce asexually by binary fission

6. Bacteria Diversity Bacteria show incredible diversity. Because of
this diversity, they are classified and grouped
according to:
Shape
Reaction to gram stain
Nutrition
Respiration

7. Cell Shape Coccus (plural cocci) – spherical
Think C – circle
Bacillus (plural bacilli) – rod-shaped
Think B – bat
Spirillum (plural spirilli) – spiral-shaped
Think S - spiral

8. Cocci (sphere) Bacillus (rod shaped) Spirillum (spiral shaped)

9. Combinations of Bacteria Shapes

10. Gram Staining Gram stain is a dye made of crystal violet and iodine
Bacteria are classified according to their reaction with gram stain.
Gram-positive bacteria
Appear purple because they retain crystal violet
Gram-negative bacteria
Appear light pink because do not retain crystal violet
Pathogenic (causing harm)
Gram positive and negative bacteria react differently because they have different cell wall compositions

11. Gram Positive and Gram Negative Bacteria

12. Nutrition
Nutrition - obtaining or creating organic compounds required for cellular metabolism
1.) source of energy
2.) source of carbon compounds
Autotrophs – make their own organic compounds. For example: synthesize glucose from carbon dioxide
Heterotrophs – obtain carbon from their environment and break it down to create organic compounds

13. Nutritional Patterns of Bacteria
Mode of Nutrition
Energy Source
Carbon source
Autotrophs
Photoautotroph
Light
CO2
Chemoautotroph
Inorganic chemicals (sulfur, nitrogen)
Heterotrophs
Photoheterotroph
Organic compounds
Chemoheterotroph
Tips to remember:
“photo” means light
Autotrophs – obtain carbon in the form of CO2 to synthesize organic compounds
Heterotrophs – obtain carbon from organic compounds.

14. Cyanobacteria - Photoautotroph
“blue-green” bacteria
Undergoes photosynthesis by using CO2 and sunlight to create organic compounds
Does not contain chloroplast
Cyanobacterial bloom – rapid population increase of cyanobacteria. Indicator of water pollution due to nitrates, and phosphates.
Lichen – cyanobacteria lives symbiotically (together) with fungi

15. Characteristics of Heterotrophs
Review: Where do heterotrophs obtain source of carbon? Parasites – absorb nutrients from living host organisms Saprobes – absorb nutrients from decomposing, dead organic matter

16. Respiration
Recall: What is cellular respiration?
Cellular respiration – breakdown of organic carbon compounds for energy
Bacteria carry out respiration on inner surface of cell membrane (vs. eukaryotes carry out respiration in mitochondria)
Aerobes – bacteria use oxygen to undergo cellular respiration
Obligate aerobes – absolutely require oxygen for survival and cellular respiration. “Obligated” to use oxygen.

17. Respiration Cont’d
Anaerobe – bacteria that carry out cellular respiration in oxygen-free environment Obligate anaerobe – presence of oxygen kills the bacteria. “Obligated” to not use oxygen. Facultative anaerobe – can survive with or without oxygen.

18. Reproduction Bacteria reproduce asexually through a process called
binary fission
Binary fission – parent cell divides into 2 identical offspring cells
Most bacteria can divide every 15 minutes as long as there is enough food, warmth and space
Growth of bacteria is exponential
Question: If bacteria can grow exponentially, then why is Earth not covered with a massive layer of bacteria?

19. Binary Fission Steps in Binary Fission: Circular chromosome attaches
to plasma membrane
2. Chromosome replicates and
daughter chromosomes attach to
different sites on plasma membrane.
Plasmid also replicates with single
chromosome.
3. Cell continues to grow.
4. Cell wall and membrane join
together.
END RESULT: 2 identical daughter cells

20. Binary Fission – Cont’d
Watch: ciWc&feature=related
Question: After having studied genetics, you know that mutations are rare. If the DNA of 1 bacterium were to contain a mutation, would this have an effect on the population?
Answer: Yes, because they reproduce rapidly through binary fission.

21. Conjugation
Conjugation – type of sexual reproduction that bacteria undergo during difficult conditions and limited sources.
Conjugation Process – bacteria connect with a long protein bridge and transfer plasmid of one bacterium to another.
Result: Bacteria now have different
genetic material
Question: How might a different
genetic makeup help the bacteria?
Answer: Help bacteria survive difficult
environmental conditions. New genes
may help bacteria to adapt to the
changing conditions.

22. Conjugation & Antibiotic Resistance
Bacteria that are resistant
contain the R-plasmid
R-plasmid contains genes that code for
enzymes that destroy specific types of
antibiotics.
Constant competition between pathogens
and scientists who develop antibiotics
Question: A bacterial population consists of bacteria that have the R-plasmid and others that do not. What will happen to the 2 different bacteria when antibiotic treatment is applied?
Answer: R-plasmid bacteria survive and can pass R-plasmid via
congujation. Bacteria without R-plasmid will die.

23. Endospore Formation
Bacteria form endospores when growing conditions are extremely unfavourable
Endospore – thick wall that surrounds DNA and cytoplasm
Endospore remains dormant until conditions are favourable for growth
Endospore of Bacillus sp.

24. Kingdom Archaebacteria
Oldest group of organisms on Earth
Live in extremely harsh environments similar to the conditions present billions of years ago on Earth. Examples: extremely salty, acidic, hot.
Groups of Archaebacteria
Anaerobic methanogen - live in oxygen-free places and produce methane gas. Example: guts of herbivores
Halophiles – “salt-loving” organisms that live in salty lakes. Example: Dead Sea
Thermophiles - live in hot,
acidic environments.
Example: hot springs.

25. Kingdom Eubacteria Contains majority of the prokaryotes on Earth
Known as “true bacteria”
Cell wall and cell membrane different from Archaebacteria
Genetically different from Archaebacteria
More than 50% of the genes are different
Examples:
Gram positive bacteria
Cyanobacteria

26. Bacteria & The Ecosystem
Nitrogen-fixing bacteria – live
freely in the soil or within the
root nodules of plants. They
convert nitrogen in the air into
nitrates for plants to use
Other bacteria feed on decomposing, dead material. They release carbon dioxide back into the atmosphere.

27. Bacteria & Disease
Pathogens – bacteria that cause diseases by producing toxins.
Toxins – deadly substances that are released into the body and cause symptoms
2 types of toxins:
Endotoxins – fatal toxins that are released when gram- negative bacteria split. Normally cause fever, vomiting and diarrhea. Salmonella and Echerichia produce endotoxins
Exotoxins – highly toxic molecules released when bacteria multiply. Examples of endotoxin diseases: tetanus and botulism

28. Other Applications of Bacteria
Waste Management
Bacteria are used to eliminate or neutralize toxic compounds in the environment
Sewage Treatment
Bacteria decompose waste and recycle organic matter. Commonly used to decompose human fecal waste.
Dairy Foods
Lactic acid bacteria are used in the production of dairy foods
Question: Are bacteria used in any other ways?