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Biology Year 1 > Cell recognition and the immune system > Flashcards

Cell recognition and the immune system Flashcards

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1
Q

What is a pathogen

A

a bacterium/virus/microorganism that causes disease and triggers immune response

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2
Q

What is the difference between Specific and Non-Specific defence mechanisms

A

Specific - doesn’t require an adaption and it is an immediate response as your are born with it

Non-Specific - (Phagocytosis) it is learnt and is for only one antigen and takes a longer time

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3
Q

How do lymphocytes recognise self body cells

A

our cells have identifiable:

  • specific molecules on its surface
  • specific 3D tertiary structure
  • lymphocytes produced in the bone marrow initially only encounter self-antigens
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4
Q

What is a phagocyte

A

a type of white blood cell that carries out phagocytosis

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5
Q

How do phagocytes defend against pathogens

phagocytosis

A
  • phagocyte follows the chemical trail left behind the pathogen
  • the phagocyte engulfs the pathogen to form a phagosome
  • lysosomes move towards the pathogen and release lysozymes which hydrolyse the pathogen
  • the left over products get absorbed into the cytoplasm of the phagocyte
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6
Q

What is a cell-mediated immunity

cellular response

A

don’t require antibodies

  • pathogens that invade body cells
  • phagocytes engulf and hydrolyse the pathogen and present the foreign antigen on its cell surface membrane
  • specific T-helper cells bind to the antigen and causing the T-helper cell to rapidly divide by mitosis and form genetically identical clones which can:
  • develop into memory cells
  • stimulate phagocytosis
  • stimulate B-cells to divide and sertete antibodies
  • activate cytotoxic T-cells (T-killer cells)
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7
Q

What is hormonal immunity

A
  • suface antigens on the pathogen are taken up by the B-cell
  • by endocytosis the B-cell’s presents the antigens on its cell surface membrane
  • T-helper cells with complementary receptor bind to these antigens and activate the B-cells go through clonal selection and divide by mitosis to either form:
  • plasma cells which secrete specific antibodies for which are complementary to the antigens on the pathogen and destroy it (primary immune response)
  • memory B-cells which get stored in the lymph nodes to respond to future infections from the same pathogen (secondary immune response)
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8
Q

How do cytotoxic T-cells kill pathogens

A

produces a protein called perforin which makes holes in the pathogens membrane making it freely permeable to substances therefore dies

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9
Q

What is an antibody

A

proteins produced by a B lymphocyte which have a specific binding site, complementary to an antigen

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10
Q

Describe the structure of an antibody

A
  • heavy and light chains make up the protein made up of 4 polypeptide chains
  • they have a antigen binding site at one end and a receptor binding site at the other
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11
Q

How do antibodies destroy pathogens

A
  • cause an agglutination of pathogen making it easier for phagocytes to locate them
  • serve as a marker to stimulate phagocytes to engulf the pathogen
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12
Q

What is a monoclonal antibody

A

an antibody produced by a single clone of cells

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13
Q

Explain a use of an monoclonal antibody

A

can be used to treat cancer by attaching to cancer cells and block the chemical signal the stimulates uncontrollable growth

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14
Q

How does a pregnancy test work

A
  • the placenta produces a protein called hCG which can be detected in the urine
  • monoclonal antibodies located in the test strip are linked to colour particles
  • if hCG is present the antibodies bind to it to make a hCG-antibody-colour complex that moves down the strip till it is trapped by another type of antibody and the colour is created
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15
Q

What are the reasons FOR and AGAINST the use of monoclonal antibodies

A

For:
-it has successfully treated many diseases

Against:

  • production involves mice that suffer
  • testing presents dangers on the user
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16
Q

What’s the difference between PASSIVE and ACTIVE immunity

A

Passive:
-introducing an individual to an antibody from an outside source

Active:
-stimulating an individual’s immune system to produce antibodies from direct contact with a dead or weakened pathogen

17
Q

What are 3 features of a successful vaccination program

A
  • must be economically available to immunitise most of the vulnerable population
  • few to no side effects of the vaccine to prevent individuals from being discouraged about taking the vaccine
  • must be possible to vaccinate the vast majority of the vulnerable population for herd immunity
18
Q

What is herd immunity

A

when a large proportion of a population has been vaccinated making it difficult for the pathogen to spread

19
Q

What are the reasons FOR and AGAINST vaccination programs

A

For:

  • reduces infection
  • herd immunity

Against:

  • testing involves animals
  • possible health risks like allergies
20
Q

What is HIV

A

a virus that causes AIDS

21
Q

What is the structure of HIV

A
  • on the outside is a lipid envelope embedded with attachment proteins
  • inside the envelope is a capsid that encloses single RNA strands and enzymes including reverse transcriptase
22
Q

what is meant by retrovirus

A

a virus that has the ability to turn RNA into DNA with the use of reverse transcriptase

23
Q

How does HIV infect CD4

A
  • HIV enters the bloodstream
  • it binds to a CD4 proteins located most frequently on T-helper cells
  • the protein capsid binds with their cell-surface membrane and the RNA and reverse transcriptase enters the t-helper cells
  • the reverse transcriptase turns the HIV RNA into viral DNA which enters the T-helper cells nucleus and DNA
  • the HIV DNA in the nucleus creates mRNA which codes for the production of more viral proteins
  • the mRNA strands move our the nuclear pores and make more HIV particles by protein synthesis
  • HIV particles break away from the T-helper cell
24
Q

How does HIV lead to AIDS

A

by HIV killing or interfering with the functions of T-helper cells, this decreases the amount of T-helper cells in the blood, and efficient cell-mediated immunity therefore the individual becomes more vulnerable to disease

25
Q

Why are antibiotics ineffective against AIDS

A

viral diseases have no metabolic pathways or cell structures for antibiotics to disrupt therefore they cannot be destroyed

Biology Year 1 (10 decks)

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