MCBoM- Definitions

Question 1

Solenoid

Answer 1

Collection of nucleosomes
= chromatin filament
Then wound into chromosome

Question 2

Azidodeoxythymidine

Answer 2

AZT
Inhibits reverse transcriptase of HIV
Good as doesn’t effect human cells

Question 3

Retrovirus

Answer 3

Vector to deliver gene in gene therapy
Infects replicating cells only
Integrates to RNA genome

Question 4

Lentivirus

Answer 4

Vector to deliver gene in gene therapy
Infects non-dividing as well as dividing cells
Integrates to RNA genome

Question 5

Adenovirus

Answer 5

Vector to deliver gene in gene therapy
Double stranded DNA
Doesn’t integrate to RNA, in episome

Question 6

Adeno-associated virus

Answer 6

Vector to deliver gene in gene therapy
Single stranded DNA
Doesn’t integrate to RNA, in episome

Question 7

Coagulation necrosis

Answer 7

Denaturation of all cytoplasmic proteins including proteolytic enzymes
Necrotic cells become tomb cells, swollen, no nuclei or any cytoplasmic detail, are just gel like structures holding tissue in place

Question 8

Liquefaction necrosis

Answer 8

Results from actin of proteolytic enzymes which convert necrotic tissue to fluid consistency
Brain tissue

Question 9

Caseous necrosis

Answer 9

Results in tissue being converted to a firm dry friable material
In tuberculosis, what happens inside granulomas
(dying cells burst in inflammation, immune response walls off diseased cells by granulomas, stops spread of bacteria so useful, but also stops O2, nutrients etc so cells die

Question 10

Gangrenous necrosis

Answer 10

Necrotic tissue secondarily affected by saprophytic organisms
Dead tissue invaded by saprophytic bacteria-> gangrene, invading healthy tissue alongside
Dry (slow moving), wet or gaseous (fast)

Question 11

Serous inflammation

Answer 11

Collection of thin exudate serous fluid below epithelium in vacule (blister)
Autoimmune- antibodies are injurious agent

Question 12

Fibrinous inflammation

Answer 12

Rich in fibrin

Eg fibrinous pericarditis so heart can’t contract properly

Question 13

Supperative inflammation

Answer 13

Rich in dead/dying neutrophils (pus)

Question 14

Ulcer

Answer 14

Abscess containing pus, surface epithelium replaced by granulation tissue (fibroblasts and newly formed blood vessels)

Question 15

Type I Hypersensitivity

Answer 15

Allergic (Immediate), eg asthma
Soluble antigens (not on surface of infected cells)
Quick onset and recovery
TH2 cytokines IL4 and IL13 switch to make IgE (TH1 cytokine IFNy suppresses)
IgE and mast cells critical
Dendritic cell picks up allergen, presents to CD4 lymphocyte, B cells make IgE, activates mast cells causing…
-increased fluid in tissues, increased blood flow and permeability
-diarrhoea and vomiting
-congestion and airway blockage, swelling and mucus secretion

Question 16

Type II Hypersensitivity

Answer 16

Cytotoxic, eg Mum/baby placenta
TH2 mediated
Mediated by antibodies and complement system to react with cell surface antigen leading to cell death
IgG or IgM expressed, binds to surface of host cells and opsonises
PHAGOCYTIC LYSIS
Target cell expresses antigens, antibodies bind, expose Fc portion, phagocytes bind, release cytotoxic material and kill target
CLASSICAL COMPLEMENT PATHWAY
Antigens on target cell bind to IgG/IgM antibodies, recognise and activate MAC (membrane attack complex) to punch hole in target cell surface leading to the lysis of the cell
ANTIBODY DEPENDENT CELLULAR CYTOTOXICITY
NK cells attach to Fc portion of antibodies, release perforins and granzymes, apoptosis

Question 17

Type III Hypersensitivity

Answer 17

Immune complex mediated, eg Lupus (butterfly rash)
Soluble antibody (IgG/M) complexes form in large amounts, overwhelm the body, become insoluble as oversaturated
Lodge in capillaries and become trapped
Activates classical complement pathway
Destroys capillary by inflammation and tissue death

Question 18

Type IV Hypersensitivity

Answer 18

Delayed, eg transplant rejection
Cell mediated, not antibody mediated
TH1 CD4 lymphocytes sensitised to antigen, produce cytokines eg IFNy to interfere with viral replication
CTL CD8 lymphocytes produced
CTLs, cytokines and macrophages cause tissue damage