Pathogens And Disease Flashcards by Mollie Beavan

For 6.15 - 6.15 and CP15 see January Mock ‘Antibiotics’

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What do microroganisms do when plants and animals die?

Secrete enzymes that decompose dead organic matter into small molecules so that they can respire

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What small molecules are released from decomposition?

Methane and CO2 are recycled back into thr atmopshere

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Describe bacteria

Single-celled prokaryotic (no nucleus) microroganisms that are a few micrometers long

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Name the parts in the structure of bacteria:

Free-floating DNA (all)
Ribosomes (all)
Cell wall (all)
Cell membrane (all)
Flagellum (most)
Pili (most)
Plasmids (most)
Slime capsule (most)

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Bacteria: Describe flagellum

Long hair-like structures thay rotate to help with movement

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Bacteria: Describe pili

Short hair-like structures that help bacteria stick to other cells and are used in gene transfer

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Bacteria: Describe free-floating DNA

Most of DNA is in one long, circular, coiled-up strand called a bacterial chromosome

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Bacteria: Describe plasmids

Small loops of DNA that contain genes for antibiotic resistance + can be passed between prokaryotes

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Bacteria: Describe the slime capsule

Protects the bacterium from attack by cells of the immune system

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Bacteria: Describe plasmsa membrane

Mainku made of lipids and proteins

Contains folds called mesosomes = artefacts produced from electron microscope preparation

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Bacteria: Describe the cell wall

Made of peptidoglycan

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Bacteria: Describe ribosomes

Produce peoteins from mRNA 70s

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Describe viruses

Micororganisms but not cells, they are simply nucleic acids surrounded by protein
Tiny

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What do bacteria have that viruses dont?

Bacteria habe plasma membrane, cytoplasm and ribosomes

Viruses do not

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Describe the components of the structure of viruses:

Protein coat
Attachment proteins 
Core of nucleic acid eg. rna or dna 
Envelope (most)
Proteins inside capsid eg enzymes (most)

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What is a pathogen?

Any organism that causes disease

Name of disease caused by a pathogen

Infectious disease

What does HIV do + why significant

Infects and destroys T helper cells which act as a host for the virus
T helper cells activate other immune system cells so hugely important

How does HIV spread?

Throigh infected bodily fluids eg. mucosal surfaces, damaged tissue, bloodstream

How does HIV reproduce?

Can only reproduced INSIDE the cells of the infected organism
HIV replicates inside T helper cells

How does HIV replicate?

Attachment protein on virus (glycoprotein) attaches to CD4 receptor molecules on cell membrsne of T helper cell
Capsid releases RNA into the cell
Reverse transcriptase makes a complementary strand of DNA from the viral RNA template
Double-stranded DNA is made and inserted into human DNA using integrase
Host cells enzymes used to make viral proteins from viral DNA
Viral proteins assembled into new virsues which bud from host cell
T killer cells kill infected T helper cells

What does HIV lead to

AIDS - conditiom where the immune system deteriorates and fails

When is someone classed as having AIDS

When symptoms of failing immune system appear

- T helper ceel count drops below certain level

Describe initial symptoms of AIDS

Minor infections of mucous membrane and revuuring respirstory infections

Describe the mid-stages of AIDS

Number of T helper cells further decreases leading to more serious infections eg. TB

Describe late stages of AIDS

Very low number of T helper cells and a serious range of infections Serious infections kill NOT AIDS itself

Name some factors affecting progression of HIV to AIDS

Strain of HIV Age Existing infections Access to healthcare

What bacteria causes tuberculosis?

Myobacterium tuberculosis

How does TB spread

When tiny droplets containing bacteria are inhaled into the lungs

Where is tuberculosis tsken up?

By phagocytes in the lungs

What happens to bacteria in tubercules?

The bacteria becomes dormant and infected person shows no symptoms

How does infection of myobacterium lead to TB disease

The dormant bacteria are reactivated and overcome the immune system More likely in people with weakened immune systems

Describe initial symptoms of TB

Fever, weakness, sever coughing

How can TB lead to death?

- Damages the lungs whcih can cause respiratory failure leading to death - Spread from lungs to other organs eg. Kidney leading to organ failure and death

Name the 4 major routes taken by pathogens

- cuts in the skin - digestive system through contaminated food - respiratory system through inhalation - muscosal surfaces eg. nose, mouth, genitals

Name the barriers that prevent infection

- stomach acid - skin - gut and skin flora - lysozyme

Describe how stomach acid acts as a barrier to infection

Acidic conditions of stomach denature enzymes in the pathogens howeber some survive and pass into intestines and invade cells of the gut

Describe how skin acts as a barrier to infection

Physical barrier | If you vut the skin, blood clots form at the area

Describe how gut and skin flora act as a barrier to infection

Intestines and skin covered in billions of harmless microorganisms that compete with pathogens for nutrients and space which limits the number of pathogens living their

Describe how lysozymes act as a barrier to infection

Mucosal surfaces produce secretions eg. Tears, saliva which contain the enzyme lyozyme that kill bacteria by damaging their cell walls causing them to burst