Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology > Module 4 Section 1: Disease and the Immune System > Flashcards

Module 4 Section 1: Disease and the Immune System Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a disease

A

A condition that impairs the normal functioning of an organism
Can affect plants and animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a pathogen

A

An organism that causes a disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the different types of pathogens

A

Bacteria
Viruses
Fungi
Protoctista
Prion (don’t need to know)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a communicable disease

A

A disease that can spread between organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Diseases caused by bacteria

A

Tuberculosis (TB)
Bacterial meningitis
Ring rot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Diseases caused by viruses

A

HIV/AIDS
Influenza
Tobacco mosaic virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Diseases caused by fungi

A

Black Sigatoka
Ringworm
Athletes foot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Diseases caused by a protoctist

A

Potato/tomato late blight
Malaria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Tuberculosis (TB)

A

Bacterium
Affects animals typically humans and cattle
Caused by bacterium mycobacterium tuberculosis
Damages and destroys lung tissue and suppresses immune system
Curable by antibiotics and preventable by improving living conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Bacterial meningitis

A

Bacterium
Affects humans
Caused by streptococcus pneumoniae or neisseria meningitidis
Affects meninges of the brain (protective membranes of brain surface) which can spread to rest of the body causing blood poisoning (septicaemia)
Cured by antibiotics if delivered early

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Ring rot

A

Bacterium
Affects potatoes, tomatoes
Caused by clavibacter michiganensis
Damages leaves, tubers and fruit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

HIV/AIDS

A

Virus
Affects humans
Pathogen called Human Immunodeficiency Virus
Disease: Acquired Immunodeficiency Syndrome (AIDS)
Destroys immune system so people are vulnerable to other diseases
Passed through exchange of body fluids (sex) and blood (needles)
No vaccine or cure but drugs can slow progress of disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Influenza

A

Virus
Affects animals including humans
Caused by orthomyxoviridae spp
Attacks and kills ciliated epithelial cells leaving them open to secondary infection
No cure but people can be vaccinated annually

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Tobacco mosaic

A

Virus
Affects tobacco plants, tomatoes, peppers, cucumbers, petunias
Caused by Tomabovirus (?)
Damages leaves, flowers, fruit
Stunts growth and reduces yield
No cure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Black Sigatoka

A

Fungi
Affects banana plants
Caused by mycophaerella fijiensis
Attacks and destroys leaves turning them black
No cure but fungicide can be used to control spread

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ringworm

A

Fungi
Affects cattle
Caused by Trycophyton verrucosum
Causes grey-white, crusty circular areas of skin in cattle
Cured using antifungal creams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Athlete’s foot

A

Fungi
Affects humans
Caused by Tinia Pedia
Grows on and digests warm, moist skin between toes causing cracking and scaling which can be itchy and sore
Cured using antifungals creams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Malaria

A

Protoctist
Affects animals including humans
Caused by Protoctista plasmodium spread by bites of infected mosquitoes (vector)
Invades red blood cells, liver and brain
No vaccine and limited cures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Potato/tomato blight

A

Protoctist
Affects potatoes and tomatoes
Oomycete phytophthora
Destroys leaves, tubers and fruit
No cure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How can communicable diseases be transmitted

A

Directly transmission
Indirectly transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How are diseases spread by direct transmission

A

When a disease is transmitted directly from one organism to another
Can be done through:
Direct contact
Inoculation
Ingestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How are diseases spread directly by contact

A

Contact with body fluids of another person
E.g. bacterial meningitis or STIs

Direct skin to skin contact
E.g. ring worm, athletes foot

Microorganisms from faeces transmitted on hands
E.g. diarrhoeal diseases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How can diseases be transmitted indirectly

A

When a disease is transmitted from one organism via an intermediate
Intermediates include:
Fomites
Droplet infection
Vectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Examples of disease that can be transmitted indirectly

A

Potato/tomato late blight is spread when spores are carried between plants - first in the air , then in the water
Malaria is spread between animals via mosquitoes
Mosquitoes act as vectors - they don’t cause malaria themselves, they just spread the Protoctista that cause it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What conditions can affect disease transmission

A

Living conditions
Climate
Social factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How can living conditions affect disease transmission

A

Overcrowded living conditions increase the transmission of many diseases
E.g. TB is spread directly via droplet infection, can also be spread indirectly because the bacteria can remain in the air and infect new people so the risk of infection is increased when lots of people live crowded together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How can climate affect disease transmission

A

Potato/tomato late blight is especially common during wet summers because the spores need water to spread
Malaria is most common in tropical countries, which are humid and hot
This is because these are the ideal conditions for mosquitoes to breed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How can social factors affect how disease is spread in humans

A

Risk of HIV infection is high in places where there’s limited access to:
Healthcare: people are less likely to be diagnosed and treated for HIV and anti-HIV drugs are less likely to be available, so the virus is more likely to be passed on to others
Health education: to inform people about how HIV is transmitted and how it can be avoided (e.g. through safe sex practices like using condoms)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How can bacteria be classified

A

By their shape
By their cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the different shapes available for bacteria

A

Bacillus/ chain of bacilli (rod)
Coccus/ pair, chain or cluster (sphere)
Vibrio (comma)
Spirillum (spiral)
Spirochaete (corkscrew)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How to test for the different types of bacterial cell wall

A

Gram staining
Different structures of cell wall react differently with the stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Results of gram staining for bacteria

A

Gram positive appear purple/blue under light microscope
Gram negative appear red under light microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How can different types of cell walls affect how bacteria are treated

A

The type of cell wall affects how bacteria react to different antibiotics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How do bacteria reproduce

A

Binary fission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Characteristics of viruses

A

Protein shell
Genetic information as RNA or DNA
0.02-0.3 micrometers
No organelles
Rapidly evolve
Non living
Always pathogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How do viruses replicate

A

Invade other cells using attachment proteins
Hijack biochemistry of the cell
Insert viral DNA into host DNA
Host cell transcribes and translates viral DNA
Host cell copies viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

How do the different pathogens damage the body

A

Viruses: hijack and destroy cells
Bacteria: produce toxins
Protists: digest cell contents
Fungi: saprotrophic feeding and digestion of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are protists

A

Eukaryotes
Single celled or colonies
Parasitic
Often require vector
Do not fall into any other categories

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are fungi

A

Multicellular
Fungi can be saprophytes: feed on dead organisms
Fungi can be parasitic: pathogenic fungi which causes disease
Fungi reproduce by making millions of spores which can spread

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How do fungi feed

A

Saprotrophic feeding
Secrete enzymes onto surface of food
Extracellular feeding
Enzymes digest food leaving nutrients
Fungi absorbs nutrients left by enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How to prevent malaria

A

Preventative measures can be used such as mosquito nets, window and door screens and long sleeves to prevent bites
Preventative measures also include controlling the vector by using insecticides and removing standing water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How are diseases spread directly by inoculation

A

Through a break in the skin
E.g. during sex (HIV)

From an animal bite
E.g. rabies

Through a wound or through sharing needles
E.g. septicaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How are diseases spread directly by ingestion

A

Taking in contaminated food or drink, or transferring pathogens to the mouth from the hands
E.g. dysentery, diarrhoeal diseases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How are diseases spread indirectly by fomites

A

Inanimate objects such as bedding, socks or cosmetics can transfer pathogens
E.g. athletes foot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

How are diseases spread indirectly by droplet infection

A

Droplets of saliva and mucus enter the air through talking, coughing or sneezing
If they contain pathogens and are breathed in by people then they can become infected
E.g. influenza, tuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How are diseases spread indirectly by vectors

A

Vectors transmit communicable pathogens from one host or another
These are often but not always animals
E.g. mosquitoes (malaria), rat fleas (plague)
Water can also act as a vector of disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

How are plant diseases spread by direct transmission

A

Direct contact of a healthy plant with any part of a diseased plant
E.g. ring rot, TMV, tomato and potato blight and black sigatoka

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

How are plant diseases spread by indirect transmission

A

Soil contamination
Vectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How is plant disease spread by soil contamination

A

Infected plants often leave pathogens or reproductive spores from protoctista or fungi in the soil
These infect the next crop
E.g. black sigatoka spores, ring rot bacteria and TMV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

How is plant disease spread by vectors

A

Wind: pathogens can be carried by the wind
Water: spores swim in the surface film of water on leaves
Animals: insects and birds carry pathogens and spores from one plant to another as they feed
Humans: pathogens and spores are transmitted by hands, clothing, fomites, farming practices and through transporting plants around the world

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Factors that affect the transmission of communicable diseases in plants

A

Planting crops that are susceptible to disease
Over crowding plants
Poor mineral nutrition reduces resistance of plants
Damp, warm conditions increase the survival and spread of pathogens and spores
Climate change causing increased rain and wind promotes the spread of disease, changing conditions allow animal vectors to spread to new areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

How do plants recognise and respond to pathogens

A

Receptors in plant cells respond to molecules from the pathogens or to chemicals produces when the plant cell wall is attacked

The stimulates the release of signalling molecules that switch on genes in the nucleus

This triggers cellular responses such as:
Producing defensive chemicals
Sending alarm signals to unaffected cells to trigger their defences
Physically strengthening cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Physical defences of plants

A

Waxy cuticles: provide barrier against pathogen entry and stops water containing pathogens from collecting on leaf
Cell walls: physical barrier against pathogens that make it through waxy cuticle
Plant produce callose: makes it harder for viruses to spread and enter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Functions of callose

A

Synthesised within minutes of the attack and is deposited between the cell walls and cell membrane in cells next to the infected cells
These callose papillae act as barriers to prevent the pathogens entering the plant cells around the site of infection

Large amounts of callose continue to be deposited in cell walls after the initial infection
Lignin is added to make the mechanical barrier to invasion thicker and stronger

Blocks sieve plates in the phloem, sealing off the infected part and preventing the spread of pathogens

Deposited in the plasmodesmata between infected cells and their neighbours, sealing them off from the healthy cells and helping to prevent the pathogen from spreading

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

How do plants use chemicals to defend against pathogens

A

Plants produce powerful chemicals to either repel insect vectors of disease or kill invading pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

How can plant chemical defences be utilised by humans

A

These chemicals can be used by humans to help control insects, fungi and bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Examples of chemicals used in plant defence

A

Insect repellants: pine resin
Insecticides: caffeine
Antibacterial compounds (including antibiotics): defensins
Antifungal compounds: chitinases
Anti-oomycetes: glucanases
General toxins: cyanide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

How do plants respond to pathogen infection internally

A

Waxy cuticle thickens
Cell walls get stronger
Guard cells close stomata in the leaf
If microbes are attacking one section of the plant, the surrounding cells self destruct to quarantine the infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

How do animals prevent pathogens getting into the body

A

Animals have a range of primary, non specific defences to prevent pathogens entering the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

How does skin act as a defence against pathogens

A

Physical barrier
Blocks pathogens from entering body
Can act as chemical barrier by producing chemicals that are antimicrobial and can lower pH to inhibit the growth of pathogens
Has skin flora of healthy microorganisms that outcompete pathogens for space on body surface
Produces sebum, oily substances that inhibits growth of pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

How do mucous membranes act as a defence against pathogens

A

Protect body openings that are exposed to the environment (e.g. mouth, nostrils, ears, genitals and anus 👅)
Some membranes secrete mucus - sticky substance that traps pathogens and contains lysozymes and phagocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

How does blood clotting act as a defence against pathogens

A

Blood clots are a mesh of protein (fibrin) fibres
The clots plug wounds to prevent pathogen entry and blood loss
Formed by a series of chemical reactions that occur when platelets are exposed to collagen from damaged blood vessels
Platelets release:
Thromboplastin: trigger series of reactions resulting in blood clot formation (thrombus)
Serotonin: causes smooth muscle in blood vessel walls contract to reduce blood flow to the area

63
Q

How does inflammation act as a defence against pathogens

A

The swelling helps to isolate pathogens that may have entered the damaged tissue
The vasodilation increases blood flow to the area which brings white blood cells to the area to fight off present pathogens

64
Q

How does inflammation occur

A

Signs include swelling, pain, heat and redness
Triggered by mast cells in damaged tissue which releases:
Histamines: makes blood vessels dilate causing localised heat and redness, raised temperature helps prevent pathogens reproducing
Histamines make vessel walls leaky so blood plasma is forced out to become tissue fluid (tissue fluid causes swelling and pain)
Cytokines: attract white blood cells (phagocytes) to the site to dispose of pathogens by phagocytosis

65
Q

How does wound repair act as a defence against pathogens

A

Skin is able to repair itself in the event of injury and re-form a barrier against pathogen entry

66
Q

How are wounds repaired

A

Epidermal cells below scab start to grow to seal the wound
Damaged blood vessels regrow
Tissue below the wound contracts to bring the edges of the wound closer together
Wound is repaired using collagen fibres - too many collagen fibres causes a scar to form

67
Q

How do expulsive reflexes repair act as a defence against pathogens

A

E.g. coughing, sneezing, vomiting, diarrhoea
Sneezes happen when the mucous membranes in the nostrils are irritated by dust or dirt
Coughing stems from irritation in respiratory tract
Both coughing and sneezing aim to expel foreign objects, including pathogens, from the body
Happen automatically
Vomiting and diarrhoea expel contents of the gut along with any pathogens

68
Q

How do tears, urine and stomach act as defence systems

A

Tears and urine contain lysozymes
Acid in the stomach
Helps prevent pathogens entering the body

69
Q

How do fevers help kill pathogens inside the body

A

Normal body temperature is around 37°C and is maintained by the hypothalamus
When pathogens invades the body the cytokines stimulate hypothalamus to increase temperature
Higher temperatures inhibit pathogen reproduction
Specific immune system works faster at higher temperatures

70
Q

What are phagocytes and how do they kill pathogens

A

Phagocytes are white blood cells that engulf and destroy pathogens
Two main types: neutrophils and macrophages
Phagocytes build up at the site of infection and attack pathogens
Pus building up in wound is a result of dead neutrophils and pathogens

71
Q

Stages of phagocytosis

A

Pathogens produces chemicals that attract phagocytes
Phagocytes recognise non-human proteins on the pathogens
This response is not specific to a type of pathogen, instead it’s against any cell or organism that is non-self
Phagocyte engulfs the pathogen and encloses it in a vacuole called phagosome
Phagosome combines with a lysosome to form phagolysosome
Enzymes from the lysosome digest and destroy pathogen

72
Q

Difference between neutrophil’s and macrophages’ times to digest pathogens

A

Neutrophils take under 10 mins to engulf and destroy a bacterium whereas macrophages take longer as they have a more complex process

73
Q

How do macrophages digest pathogens

A

When a macrophage has digested a pathogen, it combines antigens from the pathogen surface membrane with glycoproteins in the cytoplasm called the major histocompatibility complex (MHC)
MHC complex moves these pathogens antigens to the macrophage’s own surface membrane
It becomes an antigen presenting cell (APC)
These antigens now stimulate other cells involved in the specific immune system response

74
Q

What are cytokines and when are they produced

A

Produced when phagocytes have engulfed a pathogen
They are chemicals that act as cell signalling molecules
Inform other phagocytes that the body is under attack and stimulates them to move to the site of infection or inflammation
Can also increase body temperature and stimulate the specific immune system

75
Q

What are opsonins

A

Bind to pathogens and tags them so they can be more easily recognised by phagocytes
Phagocytes have receptors on their cell membranes that bind to common opsonins
The phagocyte then engulfs the pathogen

76
Q

Different types of opsonins

A

Many different types
Antibodies such as immunoglobulin G (IgG) and immunoglobulin M (IgM) have the strongest effect

77
Q

How to examine blood under a microscope

A

Smear sample
Spreading a drop of blood thinly across the slide
Can be stained to show nuclei of lymphocytes
Identifying the number of different types of lymphocytes in a blood smear indicates if a non specific or specific immune response is taking place

78
Q

What are T cells

A

T cells
Mature in the thymus
Have highly specific receptors in their membranes
Respond to ‘changed’ cells (infected cells, antigen-presenting cells, ‘non-self’ cells, mutated cells) - this is the Cell-Mediated Response
Selection of correct T cell leads to expansion by mitosis, then differentiation into variety of T cells (‘T helper’, ‘T killer’, ‘T memory’, ‘T regulator’
T cells play key roles in control and coordination of immune response

79
Q

What are B cells

A

B cells
Remain in bone marrow until mature
Congregate in lymph nodes and spleen, forming the ‘humoral response’ - roaming protection in the fluids.
Have highly specific antibodies in their membrane - each B cell can only produce one type of antibody and each B cell is unique.
Selection of correct B cell leads to expansion by mitosis, then differentiation into plasma/effector cells (which produce antibodies) and memory cells.

80
Q

Different types of T lymphocyte cells

A

T helper cells
T killer cells
T memory cells
T regulator cells

81
Q

Different types of B lymphocyte cells

A

Plasma cells
B effector cells
B memory cells

82
Q

T killer cells

A

T killer cells:
Destroy the pathogen carrying the antigen
Produce a chemical Perforin which kills the pathogen by making holes in the cell membrane so it’s freely permeable

83
Q

T memory cells

A

T memory cells:
Live for a long time and are part of the immunological memory
If they meet an antigen a second time, they divide rapidly to form a huge number of cloned T killer cells that destroy the pathogen

84
Q

T helper cells

A

T helper cells:
Have CD4 receptors on their cell surface membrane which bind to the surface antigens on APCs
Produce interleukins (type of cytokine)
Interleukins made by T helper cells stimulate the activity of B cells, which increases antibody production
Stimulates production of other types of T cells
Attracts and stimulates macrophages to ingest pathogen with antigen-antibody complexes

85
Q

T regulator cells

A

T regulator cells:
Suppress immune system, acting to control and regulate it
They stop the immune response once a pathogen has been eliminated
They make sure the body recognises self antigens and does not set up an autoimmune response
Interleukins are important in this control

86
Q

What are plasma cells

A

Plasma cells:
Produce antibodies to a particular antigen and release them into circulation
Produced from B effector cells
An active plasma cell lives for a few days but produces around 2000 antibodies per second while it’s alive and active

87
Q

What are B memory cells

A

B memory cells:
Live for a long time and provide the immunological memory
They are programmed to remember a specific antigen and enable the body to make a rapid response when a pathogen carrying that antigen is encountered again

88
Q

What are B effector cells

A

Divide to form the plasma cell clones

89
Q

Structure of antibodies

A

Y shaped glycoproteins called immunoglobulins
Two identical long polypeptide chains called the heavy chains
4 polypeptide chains held together by disulfide bridges
Also disulfide bridges within polypeptide chains holding them in shape

Hinge region of antibody provides flexibility and allows it to bind two separate antigens, one at each of its antigen binding sites

Made up of constant region which is same on all antibodies and allows attachment to phagocytes and contains only heavy chains
Heavy chains extend into variable region which contains light chains and gives specificity

90
Q

Function of antibodies

A

Produced by B cells in response to antigens
Bind to specific antigen on pathogen or toxin that has triggered immune response
Bind to antigens with a lock and key mechanism

91
Q

What is it called when an antibody binds to an antigen

A

Forms an antigen-antibody complex

92
Q

Structure of antibody binding site

A

Area of 110 amino acids on both heavy and light chains
Known as variable region since its different on each antibody and gives them their specificity

93
Q

How do antibodies defend the body

A

Antibody in antigen-antibody complex acts as an Opsonins so complex is easily engulfed by phagocytes
Most pathogens cannot invade host cells once they are part of an antigen-antibody complex
Mostly done through antibodies acting alone

Act as agglutinins causing pathogens carrying antigen- antibody complexes to clump together, helps prevent them spreading through body and makes it easier for phagocytes to engulf multiple pathogens at the same time
Done by antibodies acting in complex

Act as antitoxins by binding to toxins produced and making them harmless

94
Q

What is cell-mediated immunity

A

Where T-lymphocytes respond to the cells of an organisms that have been changed
E.g. by a virus, antigen processing, mutation or cells from transplanted tissue

95
Q

Process of cell mediated immunity

A
  1. In the non-specific defence system, macrophages engulf and digest pathogens in phagocytosis
    Process the antigens from the surface of pathogen and form antigen presenting cells (APCs)
  2. Receptors on some T helper cells fit the antigens (clonal selection)
    These T helper cells are activated to produce interleukins
    These stimulate more T cells to divide rapidly by mitosis (clonal expansion)
    Form clones of identical T helper cells that all carry the antigen to bind to a specific pathogen
  3. The cloned T cells can:
    Develop into T memory cells to respond rapidly on second infection
    Produce interleukins that stimulate phagocytosis
    Produce interleukins that stimulate B cells to divide
    Stimulate development of a clone of T killer cells that are specific for the presented antigen and then destroy infected cells
96
Q

What happens in humoral immunity

A

The body responds to antigens found outside the cells
E.g. bacteria, fungi and APCs
Humoral immune system produces antibodies that are soluble in the blood and tissue fluid and not attached to cells

97
Q

How do antibodies and pathogen antigens interact in humoral immunity

A

B lymphocytes have antibodies on their cell surface membrane (immunoglobulin M)
Pathogens entering the body carry specific antigens or produce toxins that act as antigens
B cells with the complimentary antibodies will bind to the antigens on the pathogen or to free antigens
The B cells engulfs and processes the antigens to become an APC

98
Q

Process of humoral immunity

A

Activated T helper cells bind to B cell APC
This is clonal selection: the point when the B cell with the correct antibody to overcome a particular antigen is selected for cloning

Interleukins produced by the activated T helper cells activate the B cells

Activated B cell divides by mitosis to give clones of plasma cells and B memory cells
This is clonal expansion

Cloned plasma cells produce antibodies that fit antigens on pathogen surface
They bind to and disable antigens or act as opsonins and agglutanins
This is primary immune response

Some cloned B cells develop into B memory cells
If body is infected by the same pathogen again, B memory cells divide rapidly to form plasma cell clones which produce right antibody to kill pathogen quickly
This is secondary immune response

99
Q

Why do we get ill during an infection

A

Primary immune response takes days or weeks to become fully effective against pathogen
Symptoms are a results of the body reacting when pathogens are dividing freely, before the primary immune response is fully operational

100
Q

What are autoimmune diseases

A

When the immune system stops recognising self cells and attack healthy body tissue
Can be caused by genetics, immune system responding abnormally to mild pathogen or normal bodily microorganisms or T regulator cells do not work effectively

101
Q

Examples of autoimmune diseases

A

Rheumatoid arthritis
Lupus

102
Q

What is rheumatoid arthritis

A

Immune system attacks cells in joints
Affects joints such as hands, wrists, ankles, feet
No cure
Treatment includes: immunosuppressants, pain relief

103
Q

What is lupus

A

Affect skin and joints causing fatigue
Immune system attacks cells in connective tissue
Can attack any organ in the body such as liver, lungs or brain
No cure
Treatments include: immunosuppressants, steroids

104
Q

How do plants respond to pathogen infection externally

A

An area of a plant that is under attack can warn separate areas of the infection via hormones, electrical signals or airborne compounds
When the areas detect these signals, they increase production of defensive compounds
This can also alert separate neighbouring plants of the infection as well

Plants under attack from insects can release chemicals into the air
This attract other insects (e.g. wasps) that can deter the attacking insects

105
Q

What are antigens

A

Molecules that can stimulate an immune response
Our own antigens are recognised as ‘self’, foreign antigens stimulate the production of antibodies
Specific to the organism

106
Q

Simple structure of antigens

A

Usually protein or glycoproteins with specific structure
On or inside the cell surface membrane

107
Q

When does natural active immunity occur

A

Body produces T and B memory cells after being infected with pathogen
If you meet a pathogen for a second time, your immune system recognises the antigens more quickly and launches a secondary immune response before the pathogen causes disease

108
Q

When does active artificial immunity occur

A

Active artificial immunity occurs when you become immune after you’ve been given a vaccination containing a harmless dose of antigen

109
Q

When does artificial passive immunity occur

A

Artificial passive immunity is when you become immune after being injected with antibodies from someone else
E.g. being given antibodies to beat a disease via blood donation

110
Q

What is passive immunity

A

Passive immunity is when you are given antibodies made by a different organism - your immune system doesn’t produce any antibodies of its own

111
Q

When does natural passive immunity occur

A

Natural passive immunity is when a baby becomes immune due to the antibodies it receives from its mother, through the placenta and in breast milk
This lasts until the immune system of the baby begins to make its own antibodies
The antibodies received are likely to be relevant to pathogens in its environment

112
Q

What is active immunity

A

Natural Active immunity results from having actually been infected by a pathogen.
This activates the immune system, leading to antibodies being formed by B cells.

113
Q

Active immunity summary

A

Requires exposure to antigen
Takes a while for protection to develop
Protection is long term
Memory cells are produced

114
Q

Passive immunity summary

A

No exposure to antigens
Protection is immediate
Protection is short term
Memory cells aren’t produced

115
Q

What could a vaccine contain

A

Killed or inactivated bacteria and viruses
Attenuated (weakened) strains of live bacteria or viruses
Toxin molecules that have been altered and detoxified
Isolated antigens extracted from the pathogen
Genetically engineered antigens

116
Q

Process of vaccination

A

Pathogen is made harmless so that the antigens are intact but there is no risk of infection
Small amounts of the safe antigen, known as the vaccine, are injected into the blood
The primary immune response is triggered by the foreign antigens and your body produces antibodies and memory cells as if you were infected with a live pathogen
If you come into contact with a live pathogen, the secondary immune response is triggered and you destroy the pathogen rapidly before you suffer symptoms of the disease

117
Q

What is an epidemic

A

When a communicable disease spreads rapidly to a lot of people at a local or national level

118
Q

What is an pandemic

A

When a disease spreads rapidly across a number of countries and continents

119
Q

Why is mass vaccination usually most effective at the start of an epidemic

A

This prevents the spread of the pathogen into the wider population
When vaccines are being deployed to prevent epidemics, they often have to be changed regularly to remain effective

120
Q

What is herd immunity

A

This is when a significant number of people in the population have been vaccinated
This gives protection to those who do not have immunity
There is minimal opportunity for an outbreak to occur

121
Q

Why are booster vaccines given later

A

These make sure that memory cells are produced
These can be given several years after first vaccination

122
Q

How is vaccination different from immunisation

A

Vaccination is the administration of a substance designed to stimulate the immune system
Immunisation is the process by why you develop immunity
Vaccination causes immunity

123
Q

What are some routine vaccines offered to everyone

A

MMR:
Protects against measles, mumps and rubella and is given to children as an injection at around a year old and again before they start school
Contains attenuated measles, mumps and rubella viruses

Meningitis C vaccine:
Protects against bacteria that cause meningitis C
First given as an injection at 3 months and boosters are given to 1 year olds and teenagers

124
Q

Why can vaccines change with the influenza vaccine for example

A

The flu vaccine changes every year
This is because antigens on the surface of the influenza virus change regularly to form new strains of the virus
Memory cells produced from vaccination with one strain of the flu will not recognise other strains with different antigens (strains are immunologically distinct)
Every year there are different trains of the influenza virus circulating in the population
This means a different vaccine must be made

125
Q

Why may vaccine programmes change along with the vaccine (e.g. influenza vaccine)

A

Laboratories collect samples of these different strains
Organisations, such as the WHO (world health organisation) and CDC (centre for disease control), test the effectiveness of different influenza vaccines against them
New vaccines are developed and one is chosen every year that is most effective against the recently circulating influenza viruses
Governments and health authorities then implement a programme of vaccination using the most suitable vaccine

126
Q

Why may someone be vaccinated when they are travelling

A

Sometimes people are given a vaccine that protects them from a strain causing an epidemic in another country
This helps stop the strain spreading globally

127
Q

What is antigenic shift

A

The process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains

128
Q

What is antigenic drift

A

A gradual process of genetic change that leads to more variety for each type of influenza virus due to there being different types of antigens on the surface

129
Q

What happens in the primary response

A

When a pathogen enters the body for the first time, the antigens on its surface activate the immune system as the primary response
This response is slow because there aren’t many B lymphocytes that can make the antibody needed to bind to it
Eventually the body will produce enough of the right antibody to overcome the infection, this means that the person will show symptoms
T and B lymphocytes produce memory cells, which remains in the body for a long time and can remember the specific antigen and will recognise it the second time.
This means that the person is now immune

130
Q

Why is the secondary response faster

A

If the same pathogen enters the body, the immune system will produce a quicker, stronger immune response (secondary response)
Clonal selection happens faster as memory B lymphocytes are activated and divide into plasma cells that produce the right antibody to the antigen
Memory T lymphocytes are activated and divided into the correct type of T lymphocytes to kill the cell carrying the antigen
This gets rid of the pathogen before you begin to show any symptoms

131
Q

Summarised primary response

A

Pathogen enters first time
Slow response
B and T lymphocytes activated
Show symptoms

132
Q

Summarised secondary responses

A

Pathogen enters for 2nd time
Response is fast
Memory cells activated
No symptoms

133
Q

How are many medicinal drugs manufactured

A

Many are manufactured using natural compounds found in plants, animals or microorganisms

E.g. penicillin is obtained from penicillium fungus, cancer drugs can be made using soil bacteria, daffodils are now grown to produce a drug used to treat Alzheimer’s disease

Organisms that have already been studied could still prove to be useful sources of medicines as new techniques are developed for identifying, purifying and testing compounds

134
Q

Why is maintaining biodiversity important for drug development

A

Species could die out before we get a chance to study them and we may never create cures for diseases such as AIDS

135
Q

What are pharmocogenetics

A

This is a combination of drugs that work with your individual combination of DNA
Doctors can analyse your genetics and only prescribe drugs which will be most effective for you
This can mean that more effective drugs can be manufactured in the future using this information

136
Q

How do genetics impact medication

A

Your genes determine how your body responds to certain drugs and different people respond to the same drug in different ways
This determines whether a drug is more effective or not

137
Q

What is synthetic biology

A

This involves using technology to design and make things like artificial proteins, cells and even microorganisms
This can be applied to medicine where scientists can engineer bacteria to destroy cancer cells, while leaving healthy body cells intact by producing drugs which would otherwise be too rare, expensive or unavailable

138
Q

How is nanotechnology involved in synthetic biology

A

This can also use nanotechnology where tiny, non natural particles are used for biological purposes e.g. to deliver drugs to specific sites within cells of pathogens or tumours

139
Q

Stages of drug development

A

Phase 1: small number of healthy volunteers (establish how drug works and likely dose required
Phase 2: small number of patients (can be controlled, double blind or randomised experiments)
Phase 3: larger study of patients (assess and compare drug to existing treatments)
Licensing: if drug appears to have high efficacy, is safe, and meets manufacturing standards then it can be sold by licence holder in regions covered by regulatory authority

140
Q

What are antibiotics

A

Chemicals which kill or inhibit the growth of bacteria
Used by humans as drugs to treat bacterial infections
They target bacteria cells without damaging body cells

141
Q

Why have the deaths from bacterial infections dropped recently

A

We have been able to beat bacterial infections easily using antibiotics so the death rate has fallen
This have been happening since the discovery of penicillin (from penicillium mould) by Alexander Fleming and the chemical’s use during the Second World War

142
Q

Possible risks from using antibiotics

A

Can develop severe allergic reactions in some people
Antibiotic resistance

143
Q

How do bacteria become resistant to antibiotics

A

There is genetic variation in a population of bacteria
Genetic mutations make some bacteria naturally resistant to an antibiotic

The ability to resist an antibiotic is an advantage over competition as the bacteria are able to survive in a more hostile environment (due to antibiotics providing selection pressure) so they live longer and reproduce by binary fission
Resistance alleles are also passed laterally through the population by conjugation in the form of plasmids

The allele for antibiotic resistance is passed on to lots of offspring
So resistance spreads and becomes more common in a population of bacteria over time

144
Q

Why is antibiotic resistance a problem for patients of bacterial infections

A

If the bacteria has developed resistance then the infection cannot be treated as easily using antibiotics so the infection can become more severe which could lead to death

145
Q

What can be a product of antibiotic resistance

A

Can lead to the development of superbugs that are resistant to most known antibiotics
These are becoming more common
We are less able to treat some potentially life threatening bacterial infections

146
Q

What is MRSA

A

Stands for Meticillin resistant staphylococcus aureus
This causes serious wound infections such as septicaemia
It is resistant to several antibiotics (including meticillin)
Carried by up to 30% of population on skin or in nose

147
Q

What is C. difficile

A

Clostridium difficile
Infects the digestive system which causes problems in people who have already been treated with antibiotics
Could be caused by harmless bacteria that are present in the digestive system which are killed by the antibiotics, which C. difficile is resistant to
Causes C.difficile to flourish due to lack of competition
It produces a toxin causing severe diarrhoea, fever or cramps

148
Q

How to help prevent bacterial antibiotic resistance

A

Doctors should not prescribe antibiotics for minor infections
Should not prescribe them to prevent future infections (except patients with weak immune systems, e.g, elderly people or HIV patients)
Patients should take all the antibiotics they’re prescribed to fully clear the infection and all bacteria are killed

149
Q

B lymphocyte diagram

A
150
Q

Phagocytes diagram

A
151
Q

Primary and secondary response graph

A

Primary response starts around the 5th - 10th day
Secondary starts around 25-28 days

152
Q

What type of molecule is callose

A

Polysaccharide

153
Q

T lymphocyte diagram

A

A Level Biology (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions