Microorganisms, infectious diseases, bodies defence systems and protein synthesis

Infectious Disease

Disease transmitted between organisms via pathogens.

Pathogens

Microbes causing disease by damaging cells.

Toxins

Chemicals released by pathogens disrupting cell function.

Bacteria

Prokaryotic, unicellular organisms causing diseases.

Viruses

Infectious agents requiring host cells to replicate.

Parasites

Organisms living on or in hosts, causing harm.

Fungi

Eukaryotic, multicellular organisms, some pathogenic.

Protists

Eukaryotic, mostly unicellular microorganisms.

Contact Transmission

Spread through skin or mucous membrane contact.

Faecal Transmission

Spread via contact with feces.

Bodily Fluids Transmission

Spread through blood or other fluids.

Chain of Infection

Six links: pathogen, reservoir, exit, transmission, entry, host.

Reservoir

Natural environment where pathogens survive.

Portal of Exit

Pathway for pathogens to leave the reservoir.

Means of Transmission

Pathogen transfer methods: direct or indirect.

Portal of Entry

Pathway for pathogens to enter a new host.

New Host

Organism receiving the pathogen, influencing infection severity.

Endemic

Constant disease presence in a specific area.

Epidemic

Spike in disease occurrence beyond expected levels.

Pandemic

Widespread epidemic across multiple countries.

Isolation

Separating sick individuals from healthy ones.

Quarantine

Restricting movement of exposed individuals.

Group Immunity

Proportion of immune individuals in a population.

Vector Control

Managing organisms transmitting diseases between hosts.

Micro-organisms

Invisible life forms vital for ecosystems.

Autotrophs

Organisms producing energy from inorganic substances.

Heterotrophs

Organisms obtaining nutrients from other organisms.

Cell Cultures

Growing cells in controlled environments.

Culture Medium

Nutrient solution for growing cells.

Exponential Growth

Rapid cell division under ideal conditions.

Denaturation

Protein shape change affecting its function.

pH Requirements

Optimal pH for cell growth varies by type.

What is the first line of defence?

Chemical and physical barriers that prevent pathogens from entering the body

What is the second line of defence?

The bodies innate, non-specific, immune response

What is the third line of defence?

Acquired immune responses

What are the barriers to infection? (first line of defence)

The skin, mucous membranes, secretions and stomach acid.

What is the primary function of the skin in relation to the bodies defence?

To act as an impenetrable barrier to bacteria and viruses.

What is the upper layer of the skin made of?

Dead cells containing a protein called keratin.

What substances do skin cells secrete for waterproofing?

Lipids.

What substances does the skin produce to prevent infection?

Antimicrobial substances.

What do mucous membranes line?

The digestive, respiratory, and urinary tracts.

What is the function of mucous membranes?

They trap pathogens before they enter the core of the body.

What type of cells secrete mucus in mucous membranes?

Goblet cells.

What structures line mucous membranes and help collect pathogens?

Cilia.

How can pathogens trapped by mucous membranes be expelled?

Through processes like coughing or sneezing.

How do the cilia protect the body?

By moving in a rhythmic motion and sweeping out debris and pathogens.

What are some secretions that act as barriers to infection?

Tears, saliva, and earwax.

What do tears contain that helps inhibit bacterial growth?

Antimicrobial substances

What is the function of Lysozyme found in tears?

It can destroy bacterial cell walls.

What is the pH range of hydrochloric acid in the stomach?

2-4

How does stomach acid protect the body from pathogens?

The very acidic environment in the stomach destroys any pathogens that enter the body through ingestion.

the second line of defence - Innate

innate suggesting an inborn and non-learned trait

the second line of defence - non-specific

Non-specific suggesting the defence mechanisms are general and not targeted to any particular pathogen.

How does the second line of defence work?

If a pathogen makes it past your first line of defence, your body can mount an immune response to attack and destroy the invader

What makes up the second line of defence?

phagocytic white blood cells, antimicrobial proteins and the inflammatory response

What are phagocytes?

Types of white blood cells that engulf foreign bodies.

Where do phagocytes accumulate?

At damaged areas where foreign bodies may enter.

What process do phagocytes carry out?

Phagocytosis

What triggers a localized inflammatory response?

Damage to tissue by a physical injury

What chemical is released during inflammation that causes arteriole dilation?

Histamine

What effect does histamine have on arterioles?

Causes arteriole dilation

What effect does histamine have on venules?

Causes venule constriction

What accumulates at the site of inflammation?

White blood cells

What happens to the tissues during the inflammatory response?

The tissues go red and warm due to a large amount of blood reaching the site.

What causes swelling in the area during the inflammatory response?

The tissues in the area are swollen due to the increased amount of blood.

Why is the area painful during the inflammatory response?

The area is painful due to the expansion of tissues, causing mechanical pressure on nerve cells.

What is blood clotting usually associated with?

The inflammatory response

What is the purpose of blood clotting?

To quickly heal wounds that may otherwise allow entry of pathogens

What is the third line of defence in the immune system?

The third line of defence involves a specific defence mechanism that occurs if a foreign body has penetrated beyond the surface layers of the body.

What is formed during the third line of defence?

Antibodies and specialised cells that are specific for each type of pathogen are formed.

Why is the third line of defence termed 'acquired'?

It is termed 'acquired' because specific antibodies are only created through exposure to pathogens.

What does the third line of defence allow for?

It allows for immunity.

Types of leukocytes (white blood cells.

Macrophages, Helper T cells, Killer T cells, B cells and Memory cells.

Macrophages

Macrophages destroy pathogens through phagocytosis. and break pathogens down and display their antigens. This display of antigens serves to activate other immune cells.

Helper T cells

Helper T cells bind to the antigen displayed by a macrophage or infected cell and send out signal to either B cells or Cytotoxic T cells (killer T cells).

B cells

is stimulated by the Helper T cell, and begins creating Antibodies that are specific to that pathogen.

Anti bodies

Antibodies are created by B cells, and are specific to one type of pathogen. These antibodies bind to the antigens displayed by the pathogen and deactivate it. This binding can also signal to macrophages to come and destroy the pathogen.

Cytotoxic T cells (killer T cells)

T cells which recognise foreign antigens and which hunt down and kill invading cells using chemical signals to signal the body cell to self destruct

Memory cells

memory cells remember specific antigens that have previously attacked the body so that the immune system can recognise the pathogen and produce the right kind of antibodies to fight it off.

Amount of Thymine in the body

30.3%

Amount of Cytosine in the body

19.9%

For DNA: Adenine pairs with

Thyime

Guanine pairs with

Cytosine

For DNA: Thymine pairs with

Adenine

Cytosine pairs with:

Guanine

The bases (ATCG) form:

Weak hydrogen bonds

DNA

deoxyribonucleic acid

DNA is made up of subunits called ____________

nucleotides

A nucleotide is made up of a:

Phosphate, sugar and a nitrogenous base

DNA is arranged in a:

Double helix

the sides of this double helix are made of a:

deoxyribose sugar bonded to phosphate groups

the centre of the double helix is made of:

nitrogenous bases bonded by weak hydrogen bonds

three hydrogen bonds are required to bond

Guanine and Cytosine

two hyrdrogen bonds are required to bond:

Adenine and Thymine

the bonds between the deoxyribose sugar and phosphate groups are

Strong covalent bonds

the weak hydrogen bonds between the two strands of DNA are:

easily broken by enzymes to seperate the strands for replication

DNA is a set of instructions used to tell a cell to make

proteins which are made up of chains of amino acids

Each gene is a section of a DNA molecule that codes for______

one polypeptide chain