Ch 12- Forensic Serology

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Ch 12- Forensic Serology

• Blood types and their antigens and antibodies.
• Agglutination.
• Whole blood typing.
• Characterizing a stain as blood.
• Significance of the precipitin test in serology.
• Absorption-elution techniques.
• Contribution of polymorphic enzymes and proteins
  to bloods individualization.

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• Chromosomes and genes.
• Significance of Punnet square.
• Lab tests for seminal stauns.
• Preservation of stains for lab examination.
• Collection of physical evidence in rape
  investigation.
• http//faculty.ncwc.edu/toconnor/425/425lect13.htm
  
• http//www.bxscience.edu/publications/forensicbio/
  articles/serologytoxicology/intro.htm
• http//www.rockylab.com/SEROLOGY.html

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• DNA abbreviation for deoxyribonucleic acid- the
  molecules carrying the bodys genetic
  information. DNA is double-stranded in the shape
  of a double helix
• Plasma the fluid portion of unclotted blood
• Serum the liquid that separates from the blood
  when a clot is formed
• Antigen a substance, usually a protein that
  stimulates the body to produce antibodies against
  it

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• Antibody a protein that destroys or inactivates
  a specific antigen. Antibodies are found in the
  blood serum
• Antiserum blood serum in which there are
  specific antibodies
• Agglutination the clumping together of red
  blood cells by the action of an antibody
• Serology the study of antigen-antibody
  reactions
• Hemoglobin a red blood cell protein responsible
  for transporting oxygen in the bloodstream and
  the red coloring of blood

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• Precipitin an antibody that reacts with its
  corresponding antigen to form a precipitate
•  
• Secretor an individual who secretes his or her
  blood-type antigen(s) in body fluids.
  Approximately 80 percent of the population are
  secretors
• Enzyme a type of protein that acts as a
  catalyst for certain specific reactions
• Polymorphism the existence of more than one
  form of genetic trait

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• Iso-enzymes multiple molecular forms of an
  enzyme, each having the same or very similar
  enzyme activities
• Gene a unit of inheritance consisting of a DNA
  segment located on a chromosome
• Chromosome a rodlike structure in the cell
  nucleus, along witch the genes are located. It
  is composed of DNA surrounded by other material,
  mainly proteins
• Egg the female reproductive cell
• Sperm the male reproductive cell

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• Zygote the cell arising from the union of an
  egg and a sperm cell
• X-chromosome the female sex chromosome
• Y-chromosome the male sex chromosome
• Locus the physical location of a gene on a
  chromosome
• Allele any of several alternative forms of a
  gene located at the same point on a particular
  pair of chromosomes. For example, the genes
  determining the blood types A and B are alleles

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• Homozygous having two identical allelic genes
  on two corresponding positions of a pair of
  chromosomes
• Heterozygous having two different allelic genes
  on two corresponding positions of a pair of
  chromosomes
• Genotype the particular combination of genes
  present in the cells of an individual
• Phenotype the physical manifestation of a
  genetic trait such as shape, color, and blood
  type

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• Acid phosphatase an enzyme found in high
  concentration in semen
• Oligospermia a condition describing an
  abnormally low sperm count
• Aspermia the absence of sperm sterility in
  males

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Ch 12 - Body Fluids

• Forensic Serology

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Blood

• A complex mixture of cells, enzymes, proteins
  inorganic substances
• Fluid portion of blood is called the plasma (55
  of blood content)
• primarily water
• red cells (erythrocytes)
• white cells (leukocytes)
• platelets

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What is Serology?

• A term which describes laboratory tests which
  employ a specific antigen and serum antibody
  reactions

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Erythrocytes

• Transport oxygen from the lungs to the body
  tissues
• Transport carbon dioxide from the tissues to the
  lungs
• Red cells possess chemical structures on their
  surfaces called antigens or agglutinogens
• impart blood type characteristics

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Blood Type

• Three types (alleles) of blood type gene
• A, B, O
• Each individual inherits one blood type gene from
  their mother one from their father
• 6 possible combinations (genotypes)
• AA, BB, OO, AB, AO, and BO
• Genotype determines blood type

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Antibodies or Agglutinins

• Proteins that are present in the serum
• responsible for ensuring that the only blood
  cells that can survive in a person are cells of
  the correct blood type

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• Antibodies produced by the A alleles remove any
  red blood cells containingB antigens by clumping
  them together
• Antibodies produced by the B alleles remove any
  red blood cells possessing A antigens

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Type O Blood

• Possessed by people whose genotype is OO
• both parents passed on the O gene
• have no antigens
• these cells can be introduced into a person with
  Type A or Type B because these cells are not
  attacked by the antibodies these people possess
• have both a b antibodies
• can only have other O type cells mixed with this
  blood

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Type A

• Possessed by people with genotype
• AA
• AO
• A is dominant to O
• Possesses antibody b
• will destroy any Type B red cells
• compatible with A or O red cells

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Type B

• Possessed by people with genotype
• BB
• BO
• B is dominant to O
• Possesses antibody a
• will destroy any Type A red cells
• compatible with B or O red cells

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Type AB

• Possessed by people with genotype
• AB
• A B are co-dominant
• Possesses no antibody
• can have A, B, AB, or O cells added
• Cant be added to any other blood type without
  being destroyed by an antibody

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Blood Typing

• Blood typing is done by reacting whole blood with
  antibody A and antibody B

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Blood Typing
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Relative Frequency of Blood Types in Human
Populations