Microbes as parasites

IMED2000

• example - bacteria

• cannot manufacture their own food includes some plants, all animals, protozoans, fungi

• bacteria inhabit and invade environments that can supply organic nutrients like carbohydrates, lipids and protein

• they derive organic building blocks, energy and other essential compounds vitamins, minerals and water

hetertrophs

• energy released is harnessed into energy molecules e.g. ATP

• transported to parts of the cell where processes require energy

metabolism

• breakdown of complex molecules into simpler ones, often resulting in release of energy.

catabolism

• The phase of metabolism in which simple molecules are synthesized into the complex macromolecules e.g. cell wall, enzymes, phospholipids

anabolism

• osmotic pressure

• temp

• oxgyen

• nutrition

• pH

factors effecting bacterial growth

• Requires oxygen

• Results in complete breakdown of glucose to carbon dioxide, water and a lot of ATP (~38 ATPs/glucose)

aerobic respiration

• Does not require oxygen,

• require a hydrogen acceptor (“stand-in”) e.g. sulfate, nitrogen, iron, carbon dioxide (~34 ATPs/glucose)

Anaerobic cellular respiration

• does not require oxygen, only partially breaks down glucose, not respiration, much less ATP, (2 ATPs/glucose) molecule

• Bacteria have an electron transport chain just like eukaryotic cells except it is located in the cell membrane

fermentation

• Using oxygen in metabolism creates toxic waste - Free radicals

• Bacteria that use aerobic respiration have enzymes to detoxify reactive oxygen species, catalase and superoxide dimutase

• Bacteria that don’t make these enzymes cannot survive in the presence of oxygen since they cannot detoxify these molecules - obligate anaerobes

oxgyen toxicity

• Need oxygen to stay alive

• Aerobic respiration - Use O2 as electron acceptor

Obligate (Strict) Aerobes

• Die in presence of oxygen

• Anaerobic respiration

Obligate (Strict) Anaerobes

• capable of both aerobic respiration and fermentation e.g. yeasts, many gut bacteria

Facultative Anaerobes

• Require less than atmospheric oxygen levels

Microaerophilic bacteria

• Don’t use oxygen, but are not killed by it

Aerotolerant Anaerobes

• Microbes benefit from having a place to live and multiply

• benefits host

• Some bacteria may produce vitamins (such as B and K), and break down food in our gut that host can’t normally digest

• protect host against pathogenic organisms

• take up space, so pathogen has nowhere to set up shop

• out-compete the invader for available nutrients

• may produce anti-bacterial chemicals (bacteriocins)

• Important relationship with the human immune system

mutualism

• One partner in the relationship benefits. The other neither benefits nor is harmed.

commensalism

• Exploitation of host environments

• Causes harm to their host

• Cost to the host can vary from slight to fatal

• Not always easy to determine if an organism is pathogenic e.g. mixed populations of microbes

parasitism

• viruses can’t replicate outside cells

• Avoid detection by the immune system

• Avoid immune defences

• Direct access to resources

intracellular life

• Mobility – spread rapidly

• Can cause severe tissue damage

extracellular life

• True bacteria

• Prokaryotes

• pathogenic bacteria

• Staining reactions – cell wall chemistry

• Morphology – colony and microscopic

• Physiological characteristics – environmental (O2) and nutritional

• Antigenic characteristics – serological tests

• Pathogenicity – disease causing

• Genotype – genetic makeup

bacteria classification

• Prokaryotes

• Extremophiles

• Extreme environments

archaea classification

• All eukaryotic organisms

• Fungi

• Plants

• Animals

eukaryota classification

• Usually classified according to genome type and structure of viral particle

• Virus strains are also important

• Differentiated on the basis of surface structures e.g. antigens

• Virus strains can recombine to cause new strains - influenza

virus classification

• effectively treating an infectious disease

• key features that distinguish organisms allows us to readily identify them

• allows more appropriate and effective treatment based on understanding properties of the microbe

• Predict the likely course of the disease if we understand the pathogenesis of that microbe

classification importance in health

• 1st name is the genus

• 2nd name is the epithet (describes a characteristic)

• Genus name always capitalised and italicized (or underlined)

• Epithet always lowercase and italicized (or underlined)

• Genus names can be abbreviated

naming species