E1) Some characteristics common to members of the Kingdom Bacteria include:
  • prokaryotic cell type
  • cell walls contain peptidoglycin, a polymer of sugars and amino acids
  • contains only one cell, or termed unicellular
  • may be heterotrophic or autotrophic when it comes to obtaining nutrition
  • ecologically diverse, ranging from free-living soil organisms to deadly parasites
  • some photosynthesize, and some actually require a lack of oxygen
  • may contain a flagellum or flagella, used for movement
  • also may contain pili, used to anchor the bacterium onto surfaces or other bacteria

Bacteria are significant because of their diversity and mass numbers around the world. We humans depend alot on them, even if we don't know it. Bacteria play a major role in any ecosystem, and no ecosystem would be able to thrive without bacteria present.

Prokaryotic Cell
Prokaryotic Cell
Eukaryotic Cell
Eukaryotic Cell

The main difference between a prokaryotic cell and a eukaryotic cell is that a prokaryotic cells lack a nucleus. Both of the cells have DNA, but a prokaryote's DNA is found in the cytoplasm, where as a eukaryote's DNA is found in a membrane-bound nuclear envelope.

Functions of structures found in a prokaryotic cell:

  • Chromosome - an organized structure of DNA and protein that contains genetic information that is passed on from one generation to the next
  • Plasmid - small, circular piece of DNA located in the cytoplasm of many bacteria used in recombinant DNA studies to transform bacteria
  • Ribosome - small particles of RNA and protein found in the cytoplasm, which produce proteins by following coded instructions that come from the DNA
  • Cell Membrane - thin, flexible barrier that surrounds all cells which regulates what enters and leaves the cell
  • Cell Wall - strong, supporting layer around the cell membrane which shapes and protects the cell
  • Capsule - a layer outside of the cell wall that protects against phagocytic engulfment; ables the bacteria to attach itself to surfaces
  • Slime Layer - extracellular material surrounding bacterial cells that protects it from environmental dangers such as antibiotics
  • Pili - bristle-like structures which enable a bacteria to anchor to a surface, or with other bacteria
  • Flagella - tail-like structures granting bacteria movement
  • Endospore - a thick internal wall that encloses the DNA and a portion of the cytoplasm, which allows bacteria to remain dormant for months or even years to make it possible for some prokaryotes to survive very harsh conditions

The structure of a prokaryote is significant in that it is suited for its type of life, and without even one part of the cell, the cell as a whole would have great difficulty in trying to survive or function.


- Form (shape, type of cell wall)

  • Coccus (Plural: cocci) --> Spherical Shape
Cocci bacteria bloom

  • Bacillus (Plural: Baccili) --> Rod-shaped
Baccili bacteria

  • Spirillum (Plural: Spirilla) --> Spiral + Corkscrew-shaped
Spirilla bacteria

- Type of cell wall:
  • Gram-Positive (+):
- Only has one layer (a peptidoglycan layer) it will take on a purple stain.

  • Gram-Negative (-):
- Has a peptidoglycan layer AND a lipid (Fat and sugar) layer. Since this type of cell has a lipid layer that is capable of blocking most antibiotics, its lipid layer will stop the
purple stain from entering, which will result in this cell taking on a pink stain.

- A different antibiotic will be required to get rid of these type of cells. Using antibiotics for gram (+) will not work as this type of cell has an additional layer.

PURPLE: Gram (+). PINK: Gram(-)


  • Bacteria are found absolutely everywhere except for those places sterilized by humans. Even places that seem like they could not support any life such as extremely high or low temperatures, or high concentrations of deadly chemicals have bacteria.

- Motility (Yes/No, how?):
  • Yes:
- Flagellum (plural: flagella): Propels and allows the cell to move as it rotates rapidly.

The tail-looking things are flagella

- Gliding: The slime the bacteria produces helps it glide and therefore, move.

  • No:
- Just doesn't move and stays still.

-Ecological role (Producers/ Decomposers/ Parasites/ Nitrogen Fixers):
  • Producers:
- Provides food for all beings on Earth through their sheer amount of population that provide organic molecules for consumers and so forth.
-Organic molecules are created from photosynthesis (Inorganic molecules in environment changed to organic molecules)
- Helps stabilize the food chain as well.

  • Decomposers:
- Very diverse and feed off on different variety of things. In short, decomposers have a lot of enzymes.
- Helps other organisms (mostly photosynthetic organisms) by breaking down dead organisms and recycling the raw materials in the dead matter to be used.
- Decomposers are very important because organisms need raw material for survival.
- Are also called"saprophytes"

  • Parasites:
- Absorbs nutrients from their specific hosts and inflict harm on their specific hosts.
- E.g. Pathogenic bacteria.

  • Nitrogen fixers:
- Converts nitrogen gas into ammonia (NH3), then, to nitrates, which can be used by plants and organisms with amino acids. They use up 90% of the nitrogen gas in the
environment (other 10% - lightening + weathering of storage in rocks or sediments) for other organisms to use them as nitrates.

Nitrogen fixers to the rescue~~

- Nutrition (heterotroph - saprophyte or parasite; autotroph - chemosynthetic or photosynthetic):
  • Heterotroph:
- Takes in organic molecules from environment or other organisms to use as both energy and carbon supply.
- Saphrophytes take in nutrients from dead organisms while parasites take in nutrients from living hosts.
- Saphrophytes have many enzymes, whereas parasites have a limited amount.
- Saphrophytes benefit others through their processes, whereas parasites harm others through their processes.

  • Autotroph:
- The producers in a food chain. Plants and other organisms which carry out photosynthesis are phototrophs. Bacteria which derive energy from oxidizing inorganic compounds
(such as hydrogen sulfide, ammonium and ferrous iron) are chemoautotrophs.
- Photosynthetic autotrophs are more successful than chemosynthetic autotrophs because there is sunlight everywhere across the Earth, while the specific chemical conditions for
chemoautotrophs only exist in certain, limited places.

- Human Diseases (Give 4 examples of diseases caused by bacteria):

  • Four examples are:
- Tuberculosis
- Cholera
- Meningitis
- Toxaemia

It is important to be knowledgeable about bacteria because they are everywhere and knowing them will not only help us appreciate what some bacteria do, but will also warn us about what they are capable of. Knowing things such as their composition and movement and such, we can try to develop some forms protection against the "bad" ones.

Mode of Metabolism
How energy is released
Obligate Aerobe
“requiring oxygen”
Cellular respiration
Oxygen rich areas- near water
Mycobacterium tuberculosis
Obligate anaerobe
“requiring a lack of oxygen”
Fermentation- dies if in presence of oxygen
Environments lacking oxygen- deep soil or airtight cans
Clostridium botulinum
“surviving without oxygen when necessary”
Either cellular respiration or fermentation
Both oxygen rich or poor environments
The way in which an organism releases energy is significant to humans. If a potentially lethal bacterium dies in the presence of oxygen, it is essential to give oxygen to the area where this bacterium may be located. On the other hand, if the bacterium thrives in oxygen-rich environments, then storing items in air-tight areas would kill the bacteria.

  • Photosynthesis:
- Unlike fermentation and aerobic cellular respiration, where the organic molecule (Glucose -C6H12O6 ) is broken down to obtain energy that their respective cells can use, photosynthesis is a process where the organic molecules are produced as a result of two inorganic molecules (Carbon Dioxide and Water - CO2 + H2O ) reacting together through light energy.

- Chemical equation: 6CO2 + 6H2O ----> C6H12O6 + 6O2 . ------> = Light Energy.

- Photoautotrophic prokaryotes are photosynthetic. E.g. Cyanobacteria. - Cyanobacteria is an important part of O2 producers. Helps heterotrophs in aquatic ecosystems to survive by becoming food for them.

  • Fermentation:
- Fermentation is a process where the organic molecule (Glucose) is broken down to obtain energy. In this process, O2 is not a reactant and, therefore, is not used. - The products from this process entirely depends on the enzymes that were used and involved during this process (known as fermentation) mainly because prokaryotes of different species use different enzymes to carry out fermentation. - Because the products depend on what kind of enzyme the prokaroyte has and used, it is considered an "incomplete breakdown" and not a complete breakdown.

- Some examples of this process are: C6H12O6 ----> 2C3H6O3 + 2ATP . C6H12O6----> 2C2H6O + 2CO2 + 2ATP. ----> = Enzyme.

- Things like yogurt, cheese, vinegar, sour cream, and sauerkraut can be made through fermentation by picking different bacteria to grow in certain products, like milk, fruit juice, wine, etc.

  • Aerobic cellular respiration:
- A process where the organic molecule (Glucose) is broken down to obtain energy. Similar to fermentation, but O2 is a reactant that is involved in the reaction. - Cellular respiration produces 38 ATP (19 times more ATP than fermentation products) and is considered more efficient than fermentation. - The chemical reaction for this process is universal to all obligate aerobes.

- Chemical Equation: C6H12O6 + O2 ---> 6CO2 + 6H2O + 38 ATP . ---> = Enzymes.

It is significant to these three types of energy releases as without knowledge about these processes, we would not only be able to make things such as: cheese, yogurt, etc. but we will also not be fully able to understand how we receive energy and how we live.

E6) Bacterial decomposers and parasites obtain their food in much different ways. Bacterial decomposers depend on breaking down and decomposing dead organisms for their source of food. This is a great example of mutualism because both the bacteria and the environment are affected positively. Parasites obtain their food in a much more harmful way then bacteria. Parasites obtain their food by making their way into an organism’s body eating away or attacking the organism’s internal features. Parasites also get their food by eating away at the food the organism just consumed. These two ways the parasite obtains there food can be very harmful to the organism making them sick and possibly die.



Antibiotics can be used to prevent bacterial growth because they interfere with bacterial enzymes in bacteria without harming the host enzymes (which is possible since the host is eukaryotic, whereas the bacteria inside the host are prokaryotic).

Antibiotics are chemicals that selectively kills bacteria when it is taken into the body as a medicine. Antibiotics are mostly made naturally from microorganisms in soil. E.g. Fungi [Penicillin from penicillum] and bacteria [streptomycine, tetracline, and erythromycine from streptomyces].

There are natural genetic variation that are present in a bacterial population. Some will have a mutation that will give resistance to certain antibiotics. Now, if antibiotics are overused, those bacteria that are immune to the antibiotic will be selected as the chosen ones that will survive and reproduce and pass on that resistance trait to their offspring. Now, some of those lucky bacteria without that trait may survive, but with repeated use, the bacteria will eventually turn immune (resistant).

It is significant to note how antibiotics work and how they can become immune so that we can prepare when they become immune to some antibiotics by making new ones and taking measure to reduce the bacteria's immunity.

Some bacteria are quickly becoming immune to antibiotics

E9) Not all bacteria is harmful some bacteria is actually beneficial. Bacteria can be favorable in many ways, below is a list of ways that’s can be proven.
  • Assists in breaking down, or decomposing dead organisms
  • Essential in industrial sewage treatments, helps to produce purified water and chemicals that can be used for fertilization
  • Bacteria of the genus Rhizobium often lives symbiotically within nodules attached to roots of legumes, where they convert atmospheric nitrogen into a form that’s is useable by plants
  • Nitrogen-fixing bacteria and archaea provide 90% of the nitrogen used by organisms
  • Used in production of wide varieties of food
  • Some bacteria Can digest petroleum and remove human made waste productions and poisons from water
  • Used to synthesize drugs and chemicals

E10) Pathogenic bacteria can be just as harmful as viruses to the human body. Bacteria can cause disease by destroying living cells or by releasing chemicals that upset homeostasis. There are two main ways in that bacteria produce disease:

  • Damaging Host Tissue - some bacteria destroy living cells and tissues of the infected organism directly, while some cause tissue damage when they provoke a response from the immune system
  • Releasing Toxins - bacteria release poisons, or toxins, that interfere with the normal activity of the host

The body is able to fight many various viral attacks through its lines of defence:
  • The skin, mucous membranes, and tears make up the body's first line of defence. These are commonly referred to as nonspecific defences. Our skin is a large physical barrier, with a surface primarily composed of dead cells in which very few viruses can penetrate. The mucous membrane secretes a sticky, thick fluid known as mucus. Mucus in your nose and throat traps pathogens; mucus contains lysozyme, an enzyme that breaks down bacterial cell walls. Tears contain lysozyme as well, protecting your eyes from viral infections.
  • Interferons, and phagocytic white blood cells make up the body's second life of defence. As well as the first line of defence, they are nonspecific defences. Interferons are proteins that inhibit synthesis of viral proteins (they interfere with viral growth). Interferons' main job is to buy time until specific immune defenses respond and and fight an infection. Phagocytic white blood cells are specialized white blood cells that move from blood vessels into infected tissues. What makes them special is that they have the ability to engulf and destroy bacteria they come in contact with.
  • Production of antibodies by B-lymphocytes is essential for targeting and destroying specific infections. B-lymphocytes are only capable of recognizing one specific antigen. B-lymphocytes are embedded with antibodies, which tag antigens for destruction. By producing these antibodies, B-lymphocytes are able to take care of over 10 billion antigens. The combination of the antibodies and B-lymphocytes make up the specific defences.

  • Binary Fission - process of when a prokaryote has grown to nearly double in size, and replicates its DNA while dividing in half, producing two identical cells; because this does not involve the exchange or recombination of genetic information, binary fission is a form of asexual reproduction
  • Conjugation - process of which a hollow bridge forms between two bacterial cells, and genetic material, usually in the form of a plasmid, moves from one cell to the other; even though conjugation involves the transfer of genetic material, it is still a form of asexual reproduction
  • Transformation - process in which one strain of bacteria is changed by the gene or genes from another strain of bacteria; because this involved bacteria taking DNA from their environment, it is considered primitive sexual

Terms To Know
  • Toxin - poisons that interfere with the normal activity of a host
  • Bacillus - rod-shaped prokaryote
  • Coccus - spherical prokaryote
  • Spirillum - spiral or corkscrew-shaped prokaryote
  • Antitoxin - an antibody with the ability to neutralize a specific toxin
  • Antiseptic - an antimicrobial substance applied to skin/tissue to reduce an infection