Forensic science exam

DNA

•DNA is a double-stranded molecule​, formed from two strands of nucleic acids (i.e., information-carrying molecules) held together by hydrogen bonds.​

Where is DNA?

Found in the nucleus of eukaryotic cells (e.g., plant and animal cells).

Found in the cytoplasm of prokaryotic cell (e.g., bacteria).

Chromosomes

chromosomes are huge lengths of DNA which are coiled and compacted. Humans have 46 chromosomes in total or 23 pairs

Genome

genetic information for an organism

23 pair of chromosomes

sex chromosome (fem XX male XY)

Genes

contain instructions to make proteins

alleles

Different forms of the same gene

phenotype

The physical expression of the alleles/observable characteristics

What influences your phenotype?

your genetics and your environment

Genotype

The two alleles you inherit is called

Categories of crime

Crimes against the state​

Crimes against persons (often violent crimes)​

Crimes against property​

White collar crimes​

Public order offences​

Drug offences​

Traffic offences​

Evidence at a crime scene

Trace, impressions, bodily fluids, hair clothing an material fibres, weapons and firearms, documents, CCTV footage, eyewitness testimony

Trace evidence

gunshot residue, paint residue, explosives residue, broken glass, unknown chemicals, drugs, soil, wood, pollen, fibres, hair

impressions

fingerprints, footprints, tool marks, teeth marks

Bodily fluids

blood, semen, saliva, vomit

Weapons and firearms

knives, guns, bullet holes, cartridge casings

Documents

•diaries, suicide note, phone books; also includes electronic documents like answering machines, text messages, receipts, bankcard statements

Direct evidence

first-hand observations.​
E.g. Eyewitness accounts, Video surveillance, Voice recordings, forensic lab reports, eyewitness accounts

Circumstantial evidence

•implies a fact but cannot directly prove it. ​
E.g. DNA, Ballistic evidence, prints (fingerprints, tyre prints, bite marks​)

Class evidence

narrows to a group of people ​
E.g. blood type, Shoe prints, hair (without the follicle)

Individual evidence

narrows to one individual​
E.g. DNA, fingerprints, hair (with the follicle)

Liver Mortis

The settling of blood in the body due to gravity.

Develops 2-4 hours after death;

Fixed (i.e., non-blanchable) after 8-12 hours after time of death.

Algor mortis

the cooling of the body after death, it goes down by 1.5 c every hour or in cold environments (<37 degrees) it will decrease by 2 c and then the rest will decrease by 1 c. it takes a body approx 18 - 26 hours for a body to become room temperature and algor mortis occurs 1 hour after death

Rigor Mortis

Rigor mortis is the stiffening of the muscles in a body after death.

It becomes fully developed by around 12 hours after death.

It stays for about 24–48 hours.

After that, the muscles start to break down (decompose), and the body becomes loose again.

Pallor mortis

pale or ashen discoloration of the body that occurs shortly after death. (15 - 30 minutes)

yep

yep

ATP

made by cellular respiration