- DNA fingerprinting.

- The chemical structure of everyone's DNA is the same.

- The only difference between people (or any animal)

is the order of the base pairs.

- There are so many millions of base pairs in each

person's DNA that every person has a different sequence.

-There are high diversity due to presence of non encoding

areas in the strand either in the genetic area

or outside it see here...

- Using these sequences, every person could

be identified by the sequence of their base pairs.

- Each person has a unique DNA fingerprint,

except monozygous (identical) twins.

- DNA fingerprint is the same for every cell,

tissue, and organ of a person. It cannot be

altered by any known treatment. Consequently,

DNA fingerprinting is rapidly becoming the primary

method for identifying and distinguishing among

individual human beings.

- These patterns do not, however, give an

individual "fingerprint," but they are able to

determine whether two DNA samples are from the

same person, related people, or non-related people.

Scientists use a small number of sequences of DNA

that are known to vary among individuals ,

and analyze those to get a certain probability of a matching.

------------------------------------------------

**Practical Applications of DNA Fingerprinting**

1. Paternity and Maternity :

when a father deny that a certain child is belonging

to him Or tow sets of parents claim on one child.

2. Criminal Identification and Forensics:

- In living (strong evidence of involvement

in assault,rape, disputed paternity)

as DNA isolated from blood,hair, skin cells,

or other genetic evidence left at the scene

of a crime can be compared with the

DNA of a criminal suspect .

- In Dead (DNA survives in bone for many years,

comparison of DNA with family members)

3. Personal Identification .

Enjoy it,see you,

Ibrahim

- DNA strucure and terminology.

Chromosomes are thread-like structures located inside the nucleus of cells. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.

see the picture which illustrate that also show the true genetic content & non genetic areas....

Promoters: are DNA sequences adjacent to the beginning of the genes and control gene activation.

 

Introns are sequences inside the gene although they do not code for protein sequence they are necessary for correct coding.

 

Exons are the regions inside the gene between introns that contain the coding DNA sequences. 

 

Most of the harmful mutations occur in exons and as a consequence change the structure of the coded protein.

 

- Fingerprints.

-friction skin (i.e. palms and soles) have a

impressions due to presence of ridges & grooves .

- These impressions made by dermal papillae in the dermis.

- Finger prints appear in the 4th month intrauterine life.

-Sweat glands open through minute openings on the

summits of the ridges. The sweat contains fat.

- When the skin is applied to a glistening

non-absorbable surface an impression is left behind.


Principles of fingerprint identification :

-fingerprint patterns are unique

(1 in 64 billion chance of 2 prints being identical).

-FBI has over 100 million records, no two of which are alike.

-Fingerprint pattern of an individual remains

unchanged throughout life.

-Reversible atrophy occurs in certain diseases

(coeliac disease, dermatitis).

- Some people have some skin diseases which

prevent normal formation

of fingerprints (may be genetically ).

-Permanent impairment occurs in leprosy and after

exposure to radiation.

-Attempts to mutilate fingerprints are sometimes made.

- If only the epidermis is destroyed there is no

alteration in ridge pattern.

-If dermis is destroyed additional points of

identification are created.

Types:

1-Arches.

2-Loops.

3-Whorls .

4-composite: of more than one type.

-----------------------------

poroscopy

Def: study of the pores of the sweat glands which

present at the ridges of the prints.

Position of the pores requires higher resolution scanner.

---------------

N.B: There are artificial finger prints which

used by criminals for misleading.

see you,

Dr Ibrahim

- IDENTIFICATION (4).

IDENTIFICATION OF THE DEAD

Through:

• Primary Physical Characteristics
• Secondary Physical Characteristics
• IDENTITY of DECOMPOSED or SKELETAL REMAINS

1- Primary Physical Characteristics:

- characteristics which are very difficult for a person to change during life.
Some of these characteristics will appear to alter postmortem:

-Sex.
-Age :- external appearances, internal degenerative disease, bones, joints.
-Height or stature :-
N.B. height of Body differs from that in life by up to 2-3 cm, due to joint and muscle relaxation.

-Weight :- Body often appears of different build to that in life
-Race.
-DNA (unique to every individual.)
-Fingerprints

2- Secondary Physical Characteristics:

-characteristics which can change during life,either deliberately by deceased or as a result
of medical/dental interference.
-Some of these characteristics will appear to alter postmortem:-

-Skin colour (alters post mortem).
-Eyes :- more useful in caucasians than negroid & mongoloid races.
Colour can alter PM
-Teeth :- very resistant and bear much useful information.
-Hair :- colour, style, length, beard/moustache.
-Scars :- surgical procedures and prostheses.
-Tattooing :- seen even if the body is putrefied.
-External peculiarities :- circumcision, moles, warts.
-Deformities.
-Clothing and other objects as Jewelery,Cosmetics.

-------------------------------------------

IDENTIFICATION OF THE LIVING

METHODS OF IDENTIFICATION:

The above of dead +

1-Personal impression (visual identification):

Personal impression depends on features such as

hair, moustache and beard,any gait particularities,

voice characters or hand movement during speech .

2-Photography.

3-Handwriting:

-Possible for experts to identify a person .
-we can know either the person left or right handed.
-Methods used include :

• photographic enlargement,
• analysis of ink,
• analysis of paper.

see identification (1) here...

see identification (2) here...

see identification (3) here...



Thank you for attention,

"The end of IDENTIFICATION"

Dr Ibrahim

- IDENTIFICATION (3 ).

DETERMINATION OF STATURE FROM BONES

- Long bone length (femur, humerus) is proportional to height.

- There are sex, race, nutrition and personal variations to consider

- By karl pearson formula.

Humerus = 18% of stature
Femur = 25% of stature

-----------------------------

Determination of postmortem interval from bone.

- postmortem interval (PMI) : period () death & examination.

- Are they ancient or modern bones?

(i.e. greater or less than 50 years )

-Rate of skeletonisation is highly variable.

• In the tropics a body can be reduced to a skeleton in 3 weeks.
• Remarkable preservation of body is seen in acidic peaty soil

(e.g. "Pete Bogg" from Cheshire was 200 years old!).

Thus, environmental conditions have to be taken into account.

-Naked eye appearance is unreliable:

• Tags of soft tissue, periosteum, ligaments etc, indicate less than 5 years old.
• Soapy texture of surface indicates age less than a few decades.
• Light, crumbling bones are likely to be a century or more old.

---------------------------------------
Individualizing skeletal features

• Bone disease (Paget's disease, tumours)Previous injury to bone (fracture callus, prosthesis, metallic fragments).
• Comparison of trabecular pattern of bone.
• Pattern of skull's frontal air sinuses ,Outline is unique and comparisons with antemortem X-rays are useful.
  

- Facial reconstruction:-

• Skull can be scanned into a computer and "fleshed" by computer reconstruction to give likely facial appearance in life.
• Unfortunately eye colour, hair colour and lips are independent of bony structure.

- Laboratory tests –

1.precipitin test : Immunological reaction between bone extract and anti human serum ceases within months of death.

2.If blood pigments are present bones are usually less than 10 years old.

3.Up to 20 amino acids may be identified in bones less than a century old.

4.Fluorescence of freshly sawn bone surface under UV light diminishes after 100 years.

5.New bones contain 4.0 - 4.5 gms% nitrogen; 2.5 gms% indicates approximately 350 years.

6.Radioactive carbon dating indicates which century.

see identification (1) here...

see identification (2) here...

see identification (4) here...