1. Bacteria Characteristics of Bacteria | Reproduction of Bacteria

2. Characteristics of Bacteria
Single-celled prokaryotic organisms
Contain cell walls composed of a protein and carbohydrate matrix called peptidoglycan
Structurally different from Archaea or plants
Do not contain a nucleus or membrane-bound organelles
There are thousands of different types of bacteria, but all are single-celled prokaryotic organisms. Many form clusters or colonies of cells.
Most bacteria are smaller than 10 micrometers (µm), and some are as small as .1 µm. To put this into perspective, a grain of fine beach sand is 90 µm in diameter, and the thickness of human hair ranges from μm.
All bacteria contain cell walls composed of a protein and carbohydrate matrix called peptidoglycan.
These cell walls are structurally different when compared to cell walls in Archaea or plants.
Since bacteria are prokaryotes, they do not contain a nucleus or membrane-bound organelles.

3. Characteristics of Bacteria
Nucleoid – region within bacteria where DNA is organized
Plasmids are small circular segments of bacterial DNA
All contain:
Plasma membrane
Cytoplasm
Ribosomes
Capsule – a protective coating outside of bacterial cell walls
Some contain:
Flagella which are used for locomotion
Pili function in some forms of reproduction
DNA is instead organized into a nucleoid region and small segments of plasmids.
Bacteria also contain a plasma membrane, cytoplasm, ribosomes and a protective coating known as a capsule.
Some bacteria also contain flagella that are used for locomotion and pili (singular pilus) that function in some forms of reproduction.

4. Characteristics of Bacteria
Bacteria can contain structures such as a nucleoid region, plasmids, cell wall, and flagellum.

6. Streptococcus Causes Strep Throat

7. Bacillus - E. coli

8. Spirochetes

9. Characteristics of Bacteria
Bacteria are very diverse
Some are autotrophs
Some perform photosynthesis with chlorophyll
Some perform chemosynthesis
Deep sea vents, other ocean environments, and hot springs
Some are heterotrophic
Obtain energy by absorbing or ingesting food
Ecologically, bacteria are very diverse.
Some bacteria are autotrophic, meaning that they can produce their own food.
Of these bacteria, some perform photosynthesis with chlorophyll, while others perform chemosynthesis.
Chemosynthetic bacteria have been discovered in deep sea hydrothermal vent ecosystems, other ocean environments, and terrestrial environments such as hot springs.
Other types of bacteria are heterotrophic and must obtain their energy by absorbing or ingesting their food source.

10. Characteristics of Bacteria
Aerobic bacteria – require oxygen in the process of cellular respiration
Anaerobic bacteria – do not use oxygen
Like all living things, bacteria respire. Aerobic bacteria require oxygen in the process of cellular respiration to release energy from food.
Anaerobic bacteria, in contrast, do not use oxygen.
Of these, obligate anaerobes cannot grow in the presence of oxygen.
Some are even killed in oxygen-rich environments.
Facultative anaerobes are more flexible. They may prefer oxygen, but are able to use fermentation pathways if oxygen is not available.

11. Reproduction of Bacteria
Cell division = reproduction in prokaryotes
Binary fission – simplified form of cell division used by bacteria
Steps:
DNA is replicated
Cell increases in size, splits in two
Plasma membrane pinches together and a new cell plate forms
Control of the bacterial cell cycle: growth rates, biochemical signals, and environmental conditions
In single celled organisms, cell division is the equivalent of reproduction.
Bacteria typically use a simplified form of cell division known as binary fission.
In binary fission, once the DNA is replicated, the cell increases in size and splits in two cell.
As in plant cells during cytokinesis, the plasma membrane pinches together and a new cell plate forms between the daughter cells.
The cell cycle in bacteria is controlled by growth rates, biochemical signals, and environmental conditions.

12. Reproduction in Bacteria
Binary fission in bacteria is a simplified form of cell division.

13. Reproduction in Bacteria
Ability to exchange DNA with another bacterium
Conjugation – exchange of DNA in bacteria
Similar to genetic recombination in eukaryotes
Many bacteria also have the ability to exchange DNA with another bacterium.
Similar to genetic recombination in eukaryotes, this exchange of DNA is termed conjugation.  

14. Reproduction in Bacteria
Donor bacterium connects to another bacterium using pilus
DNA is transferred to the recipient cell through pilus
Aided by proteins
DNA donated can be a plasmid
Donated DNA may contain beneficial genes
In conjugation, a donor bacterium connects to another bacterium with a pilus, an extension of the plasma membrane.
Once the two cells are in direct contact and aided by proteins, the DNA is transferred to the recipient cell through the tunnel-like opening created by the pilus.
Often the DNA donated is a plasmid and contains genes that are beneficial to the bacterium. For example, plasmids may contain genes for resistance to antibiotics or enhanced metabolic properties.

15. Diseases Caused by Bacteria
Some bacteria disrupt the health of other organisms
Pathogenic – bacteria that cause disease
Bacterial diseases are spread through:
Droplets in the air
Direct contact with the bacterium
On surfaces
In fluids
Through contaminated food
Some bacteria can disrupt the health of other organisms.
Bacteria that cause disease are termed pathogenic.
Each disease is different, but generally bacterial diseases are spread through droplets in the air (airborne), direct contact with the bacterium on surfaces and in fluids, or contaminated food.

16. Diseases Caused by Bacteria
Streptococcal disease – any bacterial disease, including strep throat, that is caused by streptococcus genus
Common infection in children
Highly contagious
Symptoms:
Sudden fever
Aches
Nausea
Red throat with possible white patches
Treated with antibiotics
Several species of Streptococcus bacteria can cause a number of diseases, most commonly streptococcal pharyngitis, known as strep throat.
While not every sore throat is caused by bacteria, this infection is common, especially in children.
Highly contagious, the infection is spread by contact with nasal or throat secretions.
Other symptoms include sudden fever, aches, nausea, and red throat with possible white patches.
It is important that strep throat is treated with antibiotics to avoid infections in the ears, tonsils, or sinuses.

17. Ecological Impact of Bacteria
Impact of bacteria on biosphere
Produce oxygen
Bacteria decompose dead plant and animal matter
Release carbon dioxide into atmosphere
Multicellular organisms have bacteria living in their digestive tract
Mutualistic relationship
Bacteria break down indigestible compounds for host to absorb
Bacteria receive nutrition and a place to live
Bacteria impact the biosphere in a number of ways.
Ocean-dwelling cyanobacteria produce a portion of the oxygen we breathe every day.
In food webs, bacteria play an important role as decomposers, breaking down dead plant and animal matter.
They return nutrients to the soil and release carbon dioxide into the atmosphere as part of the carbon cycle.
Bacteria can also maintain the health of other organisms. Many multicellular organisms (including humans) have bacteria living in their digestive tract, forming a mutualistic relationship.
The bacteria break down indigestible compounds for the host to absorb.
In return, the bacteria receive nutrition and a habitat, or a place to live.

18. Ecological Impact of Bacteria
Bacteria maintain health of organisms through biotechnology
Vaccines and antibiotics
Bacteria used in genetic engineering
Bacteria also indirectly help maintain the health of organisms through biotechnology.
Humans use bacteria to develop vaccines and antibiotics.
For example, Streptomyces griseus produces a substance toxic to competing bacteria. Biotechnologists purify this substance to produce the antibiotic streptomycin.
Lactobacillus bulgaricus is one type of bacteria used to produce dairy products such as yogurt and certain kinds of cheese.
Bacteria are also used to perform genetic engineering. These technological advances resulting from the study of bacteria help keep humans healthier.

19. Ecological Impact of Bacteria
Bacteria help in producing and cycling nitrogen
Bacteria in soil make nitrogen useable through nitrogen fixation
Break down dead organisms and waste into ammonium
Other bacteria then change ammonium into nitrates for plants
These bacterial processes allow nitrogen to cycle
From atmosphere
Through food chain
Within soil
Bacteria also help in producing and cycling nitrogen, an element essential for life.
Bacteria in the soil can make nitrogen useable through nitrogen fixation, ammonification, and nitrification.
Bacteria also break down dead organisms and waste into ammonium.
Other bacteria then change this ammonium into nitrates for plants to use.
These bacterial processes allow nitrogen to cycle from the atmosphere, through the food chain, and within the soil.

20. Nitrogen Cycle