immune response Flashcards
Describe how T lymphocytes recognise and respond to the influenza virus.
T lymphocyte receptors recognise shape of viral antigen;
clone (once only);
destroy virus;
Describe how B lymphocytes respond to the influenza virus
clone (once only);
produce antibodies;
effect of antibody e.g. stimulation of phagocytosis /
precipitation of toxins;
The MMR vaccine contains attenuated microorganisms.
What is an attenuated microorganism?
Microorganism alive/active;
But does not cause symptoms of disease/Avirulent
graph of influenza deaths: slowly decreases sudden rise explain why
fall in deaths due to rise in number of people with immunity / better care / targeting vaccination at vulnerable;
mutation of virus / new strain;
mutant form not recognised by memory cells (allow antibodies);
Neuraminidase is an enzyme which breaks down molecules in the surface membrane of epithelial cells and allows the viruses to be released from the cells.
New drugs have recently become available for treating influenza. One type is a neuraminidase inhibitor. Explain how this type of drug would act as a treatment for influenza.
alter shape of active site of neuraminidase / block active site;
virus unable to leave host cells;
Describe how HIV is replicated after it has entered a human cell.
Reverse transcriptase;
Enzyme uses (HIV) RNA to make DNA (copy);
DNA joined to (host) cell’s DNA/chromosome;
DNA used to make HIV RNA (copies);
And HIV capsid proteins/enzymes;
Made at (host) ribosomes;
Assembly of new virus particles;
Budding off from membrane (of host cell);
The destruction of T-cells by HIV leads to the death of an infected person.
Explain how.
Not enough/no T-cells to activate B-cells/lead to antibody production/activate immune system;
Person unable to fight /more prone to (opportunistic) infections/cancer;
Accept diseases
Example of infection/cancer;
A child was given the MMR vaccine and was given a second dose of the vaccine as a booster later.
(i) It took more than a week for antibodies to appear in the child’s blood after the first vaccination. Explain why.
primary response
(Takes time for) antigen to be recognised;
(Takes time for) T cells to be activated;
B-cell activation/clonal selection/expansion;
Plasma cells to make (specific) antibodies;
Time for enough antibodies to measure;
A child was given the MMR vaccine and was given a second dose of the vaccine as a booster later.
The concentration of antibodies increased immediately after the second vaccination.
Explain why.
secondary response:
Memory cells (present);
Respond immediately / can produce antibodies immediately;
Give two factors, other than cost, that should be considered when selecting an antibiotic to treat a bacterial disease.
side effects / allergic reactions / low toxicity to cells;
interaction with other drugs / effective in conditions of use / reasonably stable;
should only act on the problem bacteria / narrow spectrum;
how much resistance the bacteria have built up;
Tetracycline prevents tRNA binding
Explain how this antibiotic slows down the rate of growth of bacteria.
Suggest why tetracycline has no effect on human cells.
prevents tRNA binding to ribosomes / amino acid / mRNA;
amino acids not available / brought / picked up;
only prevents tRNA binding to 70S / prokaryotic / bacterial
ribosomes / human ribosomes are different sizes / shapes / structure;
Chloramphenicol prevents peptide bonds forming
Explain how this antibiotic slows down the rate of growth of bacteria.
chloramphenicol
prevents amino acids being joined / prevents primary structure forming;
no enzymes / no structural proteins formed;
Changes to the protein coat of the influenza virus cause antigenic variability. Explain how antigenic variability has caused some people to become infected more than once with influenza viruses.
memory B / T cells do not recognise (new antigens);
antibodies previously produced are not effective
as shape not complementary to new antigen;
Describe the role of macrophages in stimulating B lymphocytes
antigen in membrane presented to lymphocytes /
produce cytokinins;
Explain how the changes shown in the drawings (larger cell and more organelles) are related to the function of B lymphocytes.
mitochondria provide (more) ATP / energy;
(more) RER / ribosomes synthesise proteins;
(more) Golgi body secretes / modifies or packages proteins /
produces glycoproteins;
(B lymphocytes) produces antibodies;