Ch 20 Blood Stains

Question 1

Chemical examination of blood

Answer 1

Benzidine test
Phenolphthalein test

Question 2

Microchemical test for blood

Answer 2

Haemin crystal test -Trichmann’s test
Haemochromogen crystal test- takayama test

Question 3

Most delicate and most reliable test for detecting the presence of blood in both recent and old stains

Answer 3

Spectroscopic examination

Question 4

Non secretors and secretors

Answer 4

Person who possess only lipodial form of agglutinogens of the ABO system are known as non-secretors

Those who possess a water soluble form of the agglutinogens of the ABO system are known as secretors

Question 5

DNA fingerprinting definition

Answer 5

It is a technique involving chemically dividing the DNA into fragments which form a unique pattern and then matching that identity profile with the pattern obtain from similarly testing a suspect’s blood specimen.
If the two patterns match the possibility of error that is the chance that they do not belong to the same individual may be less than 1 and 30 billion

Question 6

Techniques of DNA fingerprinting

Answer 6

• RFLP- Restriction fragment length polymorphism: -multi locus probes or ; - single locus probes
• PCR- Polymerase chain reaction

Question 7

Process of rflp

Answer 7

1 isolate nuclei
2 isolated purify DNA
3 digest DNA with restriction enzyme
4 separate DNA fragments by gel electrophoresis
5 Southern transfer of DNA into nylon membrane
6 hybridization to the labelled DNA probe
7 wash the probe and membrane
8 x-ray development
9 auto radiography of DNA patterns
10 visual and computer analysis of DNA profiles

Question 8

Polymerase chain reaction PCR definition

Answer 8

It is a technique used when very small amount of DNA or partially degraded biological material is available.

A small amount of DNA is amplified more than a million fold using thermal TAQ polymerase .

It is for it is used for diagnostic purposes

Question 9

Process of polymerase chain reaction

Answer 9

1. DNA isolation split apart
2. heated more than 94°C (temperature is lower so that the small segments of DNA bind specifically to the DNA which has polymorphic regions of interest)
3. the primer act as a starting point
4. temperature is raised to 72°C
5. cycle is repeated for 30 times or more
6. DNA detection of amplification- electrophoresis by fluorescent detection or silver staining