Infectious diseases - bio

What is a disease?

Any condition that interferes with how an organism (or any part of it) functions

What is an infectious disease?

An illness resulting from the invasion of an organism’s tissues by disease causing agents/organisms, and can be transmitted from one host to another

What are pathogens

Microorganisms capable of causing illness.

They cause infectious diseases and spread from one host to another

E.g. bacteria, etc.

Why is it important to understand the nature of diseases?

• To devise effective prevention strategies

• To implement appropriate measures to safeguard public health

• Essential for identifying and combating infections effectively

• Researchers can develop targeted treatments and preventative measures to control the spread

What is susceptibility?

The likelihood of developing a disease

If the susceptibility of an organism is high, it means that their ability to resist the disease is low

What is virulence?

The ability/measure of a pathogen to cause severe disease within its host

“Disease causing capacity”

What are symptoms?

The effects the pathogen has on the host

What is the incubation period?

The time between the infection and symptoms

What are the types of pathogens?

• Bacteria

• Fungi

• Protists

• Viruses

What is bacteria?

Single-celled organisms (prokaryotic) without a true nucleus or membrane-bound organelles, they form colonies

What are some characteristics of bacteria?

• Circular DNA and simple cellular structure: cell wall, cell membrane, cytoplasm, DNA, ribosome

• Can be categorised based on their shape: cocci, bacilli, spirilia, and their response to gram staining (gram positive and gram negative)

• Some have flagella for movement and pili for attachment

What is fungi?

Eukaryotic organisms with complex cellular structure and distinct organelles, including nucleus, mitochondria, and golgi apparatus

What are some characteristics of fungi?

• Cell walls that contain chitin

• Exists in various forms, e.g. single-celled yeast and multi-cellular molds and mushrooms

• They reproduce through spores; asexually or sexually produced

What are protists?

Diverse group of eukaryotic microorganisms, ranging from single-celled to multicellular.

What are some characteristics of protists?

• Primarily aquatic and can be both free-living and parasitic

• Exhibit a variety of structural characteristics: cilia, flagella, and pseudopodia (for movement and feeding)

• Some protists, like plasmodium, are responsible for causing significant diseases, like malaria.

What is a virus?

Unique entities that straddle the line between non-living and living as they require a host cell to replicate (classified as non-cellular and not living)

What are some characteristics of viruses?

• Consists of genetic material (DNA or RNA) enclosed in a protein coat (capsid)

• Some have additional outer envelopes, derived from the host cell’s membrane, studded with spike proteins

• They lack cellular structures and organelles, making them dependent on host cellular machinery for reproduction