4.1.1 Responding to antigens

Question 1

antigens

Answer 1

macromolecules with the potential to cause and immune response
- usually proteins and can be self or nonself allowing WBC to identify pathogens and infected/cancerous cells

Question 2

self antigens

Answer 2

located on surface of cells of that organism so immune system doesn’t attack them

Question 3

non-self antigens

Answer 3

foreign macromolecules
- on pathogens or infected cells
- toxins released by bacteria
- antigens on organs from transplant
- allergens like pollen or pet hair (but not antigen since they cause allergy not disease)

Question 4

MHC class 1

Answer 4

expressed in all nucleated cells in own body

Question 5

MHC class 2

Answer 5

found on specialised cells of immune system only

Question 6

WBC

Answer 6

• have receptors complementary in shape to unique antigen enabling them to initiate specific immune response
• distinguish between self and non self antigens enabling them to mount an appropriate immune response

Question 7

disease

Answer 7

change that impairs bodily function and is not result of direct physical injury

Question 8

infectious vs non infectious

Answer 8

• infectious caused by pathogen that is cellular or non cellular
• non-infectious not caused by pathogen like cancer, autoimmune, degenerative, inherited, nutritional deficiency

Question 9

infected vs infectious disease

Answer 9

• infected is pathogen inside you and replicating
• infectious disease is sick due to pathogen (has symptoms)

Question 12

pathogen

Answer 12

infectious foreign agents with potential to cause disease can be cellular or non cellular

Question 12

non cellular

Answer 12

• no cell membrane or organelles
• extremely small
• only replicate inside cells using their organelles, molecules and enzymes
• difficult to destroy without damaging the host cell

Question 13

prions

Answer 13

• infectious proteins
• difficult to denature or digest due to having lots of packed beta pleated sheets
• e.g. central nervous system diseases like mad cow disease
• fatal with no known cure

Question 14

virus

Answer 14

• DNA or RNA enclosed in a protein coat (capsid) and sometimes lipid envelope
• surface as proteins which are complementary to receptors on host cell allowing it entry and act as antigens
• enter host cell to replicate

Question 15

viral replication DNA- adenovirus

Answer 15

• lipid envelope attaches to membrane and fuses, protein capsid removed
• DNA enters nucleus and replicates
• mRNA created (transcription)
• proteins synthesised (translation)
• viroid assembled and released using protein capsid and lipid envelope

Question 16

viral replication RNA- retrovirus

Answer 16

• protein capsid removed
• DNA made from RNA by reverse transcriptase from virus
• mRNA created (transcription)
• proteins synthesised (translation)
• viroid assembled and released using protein capsid

Question 17

how prions cause disease

Answer 17

• don’t self replicate but cause normal proteins to fold abnormally and become infectious

Question 18

how virus cause disease

Answer 18

• components of virus toxic to cell
• damage or kill host cells
• cause infected cells to produce toxic substances
• induce immune responses like inflammation or fever

Question 19

extent of virus symptoms

Answer 19

• host cell ability to regenerate
• immune system ability to destroy virus and stop it from spreading

Question 22

viroid

Answer 22

small strands of infectious RNA that uses host cell’s structure to replicate and disrupt host’s gen function

Question 23

bacteria

Answer 23

• (unicellular, prokaryotes) contains circular DNA, ribosomes, cell membranes, cell walls and no membrane bound organelles

Question 24

how bacteria cause disease

Answer 24

- transmission: enter host organism via air, food, damaged skin, sexual contact or vector - reproduction: right conditions (ph and temp) for binary fission - act adversely: host tissue is harmed often due to enzymes or toxins produced by bacteria

Question 25

fungi

Answer 25

- (heterotrophic. single or multi cellular eukaryotes) with cell wall - grow in dark damp conditions and grow in host using hyphae, reproducing via spores - can produce antibiotics that kill bacteria

Question 26

protozoa

Answer 26

- (protists heterotrophic unicellular eukaryotes) - complex life cycles partially in host and also in vector - host: species protozoan sexually reproduces in - vector/secondary host: species that transports protozoan between different hosts

Question 27

parasites

Answer 27

- organisms living in or on another organism deriving nutrition from it and causing it harm

Question 28

immunity

Answer 28

- defends the body against infection and disease, the ability to resist disease

Question 29

physical barriers

Answer 29

- prevent entry - intact skin - mucous: traps agents at respiratory surfaces - cilia: in trachea push foreign agents out and away from lungs - responses: sneezing/coughing removes agents

Question 30

chemical barriers

Answer 30

- destroy or inhibit growth - fatty acids: in sweat inhibit bacterial growth - saliva: contains antibacterial enzymes - stomach acid: low pH denatures and kills pathogens - tears: lysozymes digest bacterial cell walls

Question 31

microbiota

Answer 31

- prevent colonisation/growth - natural flora: non-pathogenic bacteria on skin and intestines that compete for space and resources with pathogens

Question 32

physical plants

Answer 32

- thick bark - waxy cuticles on leaves - forming galls to prevent spread of infection - presence of thorns and trichomes to deter insects and graziers - closing stomata to prevent pathogen invasion

Question 33

chemical plants

Answer 33

- various enzymes that are antifungal