Topic 6- Glossary Flashcards
Fingerprints
The pattern of skin folding on the fingers of humans (and some other animals) – each person’s pattern is unique.
DNA fingerprinting or DNA profiling
A technique to identify individuals; relies on differences in the number of times a mini- or micro- satellite sequence is repeated on each chromosome. At least 10 or more microsatellite sequences are used to produce a unique profile for each individual with the exception of identical twins.
Dental records
*Records of these can be used to identify bodies that are damaged, as they are very slow to decay, and more resistant to burning.
Introns
Non-coding bocks of DNA, or intragenic regions.
Exons
Coding regions of DNA, or expressed regions.
Short tandem repeats
Another term for satellites- DNA sequences within introns repeated many times. Also known as mini or micro-satellites.
Restriction enzyme
Or restriction endonuclease
An enzyme produced by bacteria that can cut DNA molecules at specific sites.
Recognition site
The sequence of nucleotides in DNA to which a restriction enzyme binds and then cuts the DNA.
Agarose gel electrophoresis
Use of an agarose gel matrix placed in salt buffer in which molecules of DNA can be separated on the basis of size, when a current is passed through the gel.
Southern blotting
The process by which DNA fragments are transferred from the agarose gel to a nylon or nitrocellulose membrane.
Nylon or nitrocellulose membrane
A charged membrane that provides a solid support to which DNA separated by gel electrophoresis can be transferred. Used to allow subsequent manipulations of the DNA.
Agarose
A substance that when heated with buffer and cooled forms a gel.
Hybridisation
The process where two complementary DNA strands will anneal (bond together) by hydrogen bonding
X-ray film
Light or radioactive sensitive film.
Labelled DNA probe/gene probe
A short single stranded length of DNA, that is complementary to a target gene sequence that has attached to it a fluorescent or radioactive marker.
Polymerase chain reaction
A technique that allows the automated replication of a particular stretch of DNA using a thermostable DNA polymerase. Involves several rounds of denaturation, annealing of primers to the template strand, and polymerase extension from the primers. It will result on many identical copies of the target sequence.
DNA polymerase
An enzyme which catalyses the joining together of individual nucleotides to form a molecule of DNA.
Primers
Short single stranded sections of DNA used in the above procedure, which are complementary to the sequence either side of the target sequence. They are marked with a fluorescent tag.
Amelogenin (amg) gene
Gene found on the X and Y chromosome, which codes for a protein found in tooth enamel. The alleles on the X and Y chromosome are different lengths and provides a method for determining gender on a DNA profile. PCR of this gene will produce 1 band on a gel if female and 2 bands if male.
Core temperature
Internal body temperature – 36.2 - 37.6C
Sigmoid curve
Cooling of the body follows a __________ __________
Rigor mortis
The stiffening of muscles after death due to lack of ATP in muscle cells
ATP
Adenosine triphosphate. The common “energy currency” of all cells.
Lactic acid
Chemical formed by anaerobic respiration in animal cells, which causes the pH to drop, inhibiting further enzyme reactions.
Decomposition
Also known as putrefaction; the break-down of body tissue to simpler molecules.
Autolysis
Early stage of decomposition involving the body’s own enzymes from the digestive tract and lysosomes.
Bacteria
Enzymes will also be released from these organisms, resulting in further decomposition and gas formation.
Greenish decolourisation
One of the first signs of decomposition
Hydrogen sulphide, methane, carbon dioxide ammonia and hydrogen
Bloating of the body due to these gases building up in the gut and tissues
36-72 hours after death
Time taken for discolouration of abdominal wall to occur
1 week, 3 days if temperature 26-30 C
after death
Time taken for gas formation to occur
Forensic entomology
The application of knowledge about insect lifecycles to estimate time of death.
Larva
The pre-adult form of fly that hatches from an egg, also called a maggot.
Instar
An immature stage of an insect between successive molts.
Pupa
Stage between larva and adult of some insects during which metamorphosis occurs.
Calliphora vicina,
Most common blue bottle (or blowfly) found on bodies
Cocaine
An example of a drug that can affect the rate of maggot development.
Succession
In entomology, the gradual sequential series of changes in species of insect found in a decomposing body. Note, unlike with the comparable situation with plants, most of the early insects will still remain on the body.
Decomposers
The bacteria and fungi essential in sustaining the carbon cycle are also known as these.
Post mortem
The examination of a dead body to ascertain cause of death.
Tuberculosis
A contagious disease principally affecting the lungs, caused by the bacterium Mycobacterium tuberculosis
Human immunodeficiency virus (HIV)
A human retrovirus which that infects T helper cells and so disables the immune system, leading to AIDS.
AIDS
The result of infection by HIV, where the immuno-compromised person is susceptible to opportunistic infections.
Peptidoglycan
A polysaccharide, cross-linked by peptide chains, and the major constituent of the bacterial cell wall.
Gram positive bacteria
These bacteria have walls that are thickened with additional polysaccharides and proteins.
Gram negative bacteria
These bacteria have thinner walls, but also have a surface layer of lipids for protection.
Pilus (plural pili)
Protein tubes that allow bacterial attachment to surfaces and cells.
Mesosome
Infolding of the bacterial cell surface membrane and the site of respiration.
Capsule
Mucus layer surrounding the cell wall of the bacteria providing protection and preventing dehydration; it also allows bacteria to form colonies. Only present in some bacteria, e.g. TB
Flagellum
Used for cell movement.
Plasmid
Small circles of DNA found in some but not all bacteria, in addition to the main loop of genomic DNA.
Glycoprotein
Compound of protein and polysaccharide.
Host
Organism supporting a parasite (e.g. a virus), in or on its body to its own detriment. (Can also be used to describe an organism supporting a commensal organism.)
Lysis
Destruction of cells through damage of the plasma membrane.
icosahedral
Viruses come in a wide variety of shapes and sizes; a spherical virus is also described as _____________
Tobacco mosaic virus
First virus discovered. A rod shaped plant virus.
Bacteriophage
A virus that infects bacteria.
Pathogen
A disease causing parasite, usually a microorganism.
Droplet infection
Infection by inhalation of droplets of mucous and saliva containing the infectious organism.
Body fluids
HIV is carried in some of these, e.g. blood, vaginal secretions, and semen, (but NOT saliva or urine).
Sexually transmitted infection
Any diseases transmitted through (unprotected) sexual contact.
Maternal transmission
Transfer of HIV from mother to unborn child or infant.
Immune response
Mechanisms mounted by the immune system to attempt to destroy an invading pathogen.
Antigen
Any large molecule that triggers an immune response by lymphocytes. These are usually proteins, but may be other types of molecule such as polysaccharides, or lipids.
Antibodies secreted by lymphocytes will bind (specifically) to these molecules.
Lysozyme
Enzyme found in tears, saliva and nasal secretions, that kills bacteria by breaking down their cell walls
Inflammation
A non-specific response to infection which results in redness, oedema, pain and an increase in temperature. Due to the release of histamine from damaged white blood cells and mast cell.
Mast cells
Cells found in connective tissue below the skin and around blood vessels, which release histamine (along with damaged white blood cells) in response to cell damage.