Micro-organisms Ch:13

Micro-organisms are small living organisms that can be seen using the microscope. Bacteria, viruses and fungi are known as micro-organisms. Micro-organisms that are harmful are known as pathogens.

%%What is microbiology?%% Microbiology is the study of microscopic organisms (micro-organisms).

%%What is a micro-organism?%% A micro-organism is a tiny living thing that cannot be seen with the naked eye.

%%What is a pathogen?%% A pathogen is a harmful micro-organism.

Bacteria

Bacteria are a type of micro-organism that are made of one cell only. We say they are %%unicellular.%% This means that the entire organism is made of only one cell.

Bacteria can be found anywhere. They can even survive under extreme pressures and temperatures.

Bacteria have three basic shapes.

  1. Round (pathogenic round bacterial diseases often include ‘cocci’ in the name). Common infections include pneumonia, streptococcus, staphylococcus.
  2. Rod (names often include ‘bacilli’). Common infections include TB, tetanus, botulism.
  3. Spiral (names often include ‘spirilla’). Common infections include syphilis, cholera.
Bacterial Reproduction

Bacteria reproduce asexually, meaning reproduction that involves only one parent. When conditions are favorable, bacteria will reproduce. Factors that affect this include

^^Temperature.^^ Enzymes affect bacterial growth, therefore most grow best between 25-40 degree Celsius.

^^Oxygen Concentration.^^ Aerobes are bacteria that require oxygen. Anaerobes are bacteria that do not.

^^pH concentration.^^ Bacteria prefer an environmental pH of 7-8 but some will survive acidic or alkaline conditions.

^^External solute concentrations.^^ Bacterial cells absorb water. When they are in high solute solutions, water will move out of the bacteria, so it will die.

^^Pressure.^^ The cell wall may collapse if pressure is too high.

Mutations in bacteria

A mutations is a change in the DNA. Bacteria have a very short life cycle (20 minutes) mutations can be passed on very quickly to the next generation of bacteria.

Antibiotics

An antibiotic is a medicine that stops the growth of / kills bacteria and fungi, e.g. streptomycin, penicillin. Antibiotics only work against bacterial and fungal infections. They do not affect viruses.

Antibiotic-resistant bacteria are bacteria that will no longer be affected by antibiotics that previously destroyed them. Antibiotic resistant strains of bacteria will survive and thrive because they do not have as much competition anymore.

  1. Overuse of antibiotics causes an increase in the development in antibiotic-resistant bacteria.
  2. When a prescription of antibiotics is not finished, some pathogenic bacteria will survive and re-grow. This may also encourage the growth of antibiotic-resistant bacteria.
  3. If we come in contact with the pathogen in the future, the antibiotics may no longer work.

\ A few bacteria have a mutation that makes them resistant to antibiotics, Antibiotics kill most the bacteria causing the illness, The antibiotic- resistant bacteria are now able to reproduce, Some bacteria can ‘give’ their drug resistance to other bacteria.

Importance of Bacteria for Human Health

 @@BENEFICIAL BACTERIA@@

  • They make insulin, enzymes and amino acids for the food and medical industry.
  • They can produce antibiotics, e.g. streptomycin.
  • They can help to make silage to feed cattle.
  • Lactobacillus are used to covert milk to cheese and yoghurt.

@@HARMFUL BACTERIA@@

  • They cause diseases including meningitis, TB, strep throat, and cholera.
  • They can cause food poisoning in animals and people.
  • They cause milk to go sour.
  • They can cause crop diseases.

Fungi

Most fungi are multicellular.

Fungi do not contain chlorophyll and cannot make their own food. Some fungi absorb nutrients from dead organic matter. This makes them important in nature because they help to cause the delay of dead plants and animals. They are decomposers.

Other fungi are parasites. This means that they live on living matter or hosts and don’t provide any benefit to the host. Ringworm, athlete’s foot and potato blight are types of parasitic fungi.

Whatisadecomposer?What is a decomposer? This is an organism that causes dead plants and plants and animals to rots or decay.

Whatdoesmulticellularmean?What does multicellular mean? Multicellular means that the organism has many different types of cells cells that work together to carry out all functions in the organism.

Whatisthatorganicmatter?What is that organic matter? This is material from an organism that once was living.

Whatisaparasite?What is a parasite? This is an organism that lives at the expense of or on it’s host.

Whatisahost?What is a host? This is an organism that supports a parasite, e.g. a dog is a host to fleas.

How do fungi impact our everyday life?

@@BENEFICIAL FUNGI@@

  • Yeast is used in brewing to make alcohol.
  • Yeast is used in baking to make bread.
  • Penicillin is used to make antibiotics.
  • We can eat some mushrooms

@@HARMFUL FUGNI@@

  • They cause diseases such as ringworm and athlete’s foot.
  • They cause diseases in plants.
  • Many mushrooms are poisonous.
  • Bread mold and fruit mold cause food spoilage.

Viruses

Viruses are so small they cannot even be seen with light microscopes. Viruses are parasites and they cannot survive or reproduce without the help of another living organism, e.g. Covid.

Viruses have a very simple structure and are made of protein and DNA.

Reproduction

Viruses do not reproduce in the same way as bacteria or fungi. Instead, they reproduce by a process called viral replication.

  1. The viruses injects its DNA into a host cell.
  2. The virus’s DNA multiplies inside the cell.
  3. New viruses are assembles from DNA.
  4. The host cell bursts, releasing the viruses.
Methods for fighting Viral Infection
Vaccines

A vaccine is a weakened, dead or small dose of a disease- causing micro-organism. When a vaccine is placed in the body, it triggers the body to start producing its own defence's against the virus we want to avoid. This means that if the person comes into contact with the virus in the future, they will not get sick. Your blood will recognize the invader and destroy it when enters the body.

Young children are given the MMR vaccine, which helps to protect them from measles, mumps and rubella.

How do viruses affect our everyday lives?

@@BENEFICIAL EXAMPLE@@

Bacteriophanges destroy bacteria invading the body.

@@HARMFUL EXAMPLES@@

Common Cold

Covid19

Influenza

Warts

HIV and AIDS.

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