Disease - 4 Flashcards by Matthew Stewart

How does the waxy cuticle act as a plant defence

physical barrier and no water collection on wax

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How does the cell wall act as a plant defence

barrier and contains chemicals

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How does callose act as a plant defence

Prevents pathogens entering cells

Can also block phloem sieve plates,
preventing spread of pathogen

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What is callose

Polysaccharide deposited between
cell walls and membranes when a
plant is infected

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What are chemical plant defences

Antimicrobial chemicals which kill or inhibit the growth of pathogens - saponins

Chemicals toxic to vectors

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What are primary defences

Prevent the entry of a pathogen into an organism

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What are non-specific defences

Defences that will act on any type of pathogen

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Examples of primary non-specific defences in animals

Skin
Blood clotting
Inflammation
Expulsive reflexes
Mucous membranes
Wound repair

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What are the 2 types of white blood cells

Lymphocytes
Phagocytes

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What are the 2 types of phagocytes

Macrophages
Neutrophils

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Features of neutrophils

Multi-lobed nucleus
Short lived and released in large numbers
Undertake phagocytosis

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Features of macrophages

Made in bone marrow
Travel through blood
Undertake phagocytosis
Display antigens

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Describe the process in phagocytosis

The phagocyte recognises the antigens on the surface of the pathogen

Phagocyte engulfs the pathogen by folding its membrane inwards

This forms a phagosome

Lysosomes then fuse with the phagosome (phagolysosome)

Lysosomes release enzymes (lysins) to digest the pathogen

Harmless products absorbed

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What are opsonin’s

Proteins in the blood that attach to the surface of pathogens to aid
phagocytosis

They serve as a marker and ‘tag’ pathogens

Phagocytes have receptors for opsonins and bind to them, the phagocyte
then engulfs the pathogen

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what are cytokines

Cytokines

Proteins in the blood that attract phagocytes via cell signalling

Phagocytes that have engulfed a pathogen produce cytokines

When other phagocytes pick up the cytokine signal it informs them the
organism is under attack and phagocytes move to the site of infection

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Features of the specific immune response

attack a specific pathogen
Much slower at first
Faster on second infections
More effective

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What are antigens

Usually proteins or glycoproteins
Have a specific shape
Foreign antigens trigger immune response

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What are antibodies

Y shaped proteins produced by B plasma cells
Have a complimentary shape

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What are the 2 types of lymphocytes

T cells
B cells

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Describe the structure of an antibody

Two heavy polypeptide chains
Two light polypeptide chains
Variable region
Antigen binding sites
constant region
Hinge region

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How are the polypeptide chains held together

By disulphide bridges

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What is the function of the variable region

Varies between antibodies
specific to an antigen

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What is the function of the antigen binding site

complementary shape
to a specific antigen

two of these

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What is the function of the constant region

Allows phagocytes to attach to antibody for phagocytosis
Same in all antibodies

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What is the function of the hinge region

Allows flexibility if binding to more than one antigen

What are the three types of antibodies

agglutinins Opsonins Antitoxins

What are agglutinins

Antibodies which stick pathogens together (via the antigens) This hampers mobility of pathogens and allows phagocytes to engulf a larger number of pathogens

What are opsonins

Bind to antigens via the antigen-binding site Bind to the phagocytes via the constant region Makes it easier for phagocytes to find and engulf pathogens

What are antitoxins

Binds to toxins produced by pathogens to make them harmless

What is clonal selection

Each type of cell has a different function The selection of the correct T and B lymphocytes for the immune response is known as clonal selection These lymphocytes must increase in number to become effective They divide by mitosis in a process called clonal expansion

What are the 4 types of T lymphocytes

T helper T killer T regulator T memory

What is the function of T helper cells

Release interleukins which allow: B cells to differentiate Production of other T cells Macrophages to ingest pathogens

What is the function of T killer cells

Attack and destroy infected body cells using a chemical called perforin to pierce the cell membrane and then secreting cytotoxins into the cell

What is the function of T regulator cells

Shut down the immune response after the pathogen has been removed

What is the function of T memory cells

Involved in immunological response Remain in the body for years Involved in secondary response produces more T cells

What are the 2 types of lymphocytes

Plasma cells Memory cells

What is the function of plasma cells

Manufacture and release antibodies very quickly

What is the function of memory cells

Remain in the body for years and acts as immunological memory, respond very quickly to secondary responses

What is active immunity

When your immune system is activated and you make antibodies and memory cells

What is passive immunity

Provided by antibodies not made in your system

What is natural immunity

Gained normally with no help

What is artificial immunity

Is gained by deliberate exposure to antigens or antibodies

What are vaccinations

A deliberate exposure to antigenic material activates the immune system to make an immune response and provide immunity

What are the 4 types of drugs and medicines

Antibiotics Anti-virals Antiseptics Painkillers

What plant is digitalis made from

Foxgloves

What plant is aspirin made from

Willow

Why is biodiversity important in drug production

Most drugs are derived from plants Without good biodiversity, we lose some of these derivatives for important new medicine

What is personalised medicine

Genomes of individuals can be sequenced Medicines can be produced that are more effective to a persons DNA

What is synthetic medicine

Biologists can now make artificial proteins, enzymes, cells and microorganisms

What is a pathogen

A microorganism that causes disease

What is a disease

A condition that impairs the normal functioning of an organism

what is a communicable disease

A disease that can spread between organisms

What are the 4 types of pathogens

Bacteria Fungi Protoctista Viruses

Describe the features of Fungi

Multicellular or unicellular Chitin cell wall Network of fibres called hyphae

Describe the features of viruses

Parasites Much smaller than bacteria None living Reproduce inside other cells made of genetic material

Describe the features of proctists

Single celled Eukaryotic Some features of plant and animal cells

What are 3 examples of bacterial diseases

TB Bacterial meningitis Ring rot

What are 2 examples of viral diseases

HIV Influenza

What are 2 examples of protoctisal diseases

Malaria Late blight

What are 3 examples of fungal diseases

Black sigatoka Ring worm Athletes foot