Biological Evidence

Question 1

What are mitochondria ?

Answer 1

Cellular organelles responsible for energy production through oxidative phosphorylation

Question 2

Where are mitochondria located ?

Answer 2

Cytoplasm

Question 3

How many genes do mitochondria have ?

Answer 3

37

Question 4

what is the inheritance pattern of mitochondrial DNA ?

Answer 4

MtDNA is inherited exclusively from the mother. All maternal relatives share the same mtDNA sequence

Question 5

When was mtDNA fully sequenced ?

Answer 5

1981

Question 6

What are the advantages of using mitochondrial DNA ?

Answer 6

-high copy number: each cell contains hundreds of thousands of mitochondria
-maternal linage tracing: allows for identification of maternal relatives across generations
-databases can be created

Question 7

What are the limitations of using mitochondrial DNA ?

Answer 7

-lack of individuality: mtDNA is shared among all maternal relatives across
-Heteroplasmy: the presence of multiple mtDNA types within an individual, which can complicate interpretation

Question 8

Where is the most mitochondria most likely to be found ?

Answer 8

The more energy the tissue requires the more mitochondria

Question 9

What are mitochondria critical for ?

Answer 9

Cellular metabolism and function

Question 10

What is Sanger sequencing ?

Answer 10

-uses single-stranded DNA template, primer, DNA polymerase, ddNTPs and fluorescent labels
-ddNTPs terminate DNA extension and emit specific wavelengths of light
-sequence determined by electrophoretic separation

Question 11

What is the Y chromosome ?

Answer 11

One of the two sex chromosomes in males

Question 12

What is the Y chromosome characterised by ?

Answer 12

• approximately 60 million base pairs
  -contains 200 genes
  -passes exclusively from father to son
  -highly stable

Question 13

What is the inheritance pattern of the Y chromosome ?

Answer 13

Inherited only through male lineage, sons receive Y-chromosome from their fathers

Question 14

What are the advantages of using Y chromosomes ?

Answer 14

-tracing paternal lineages
-male-specific, allowing for isolation of male DNA in mixed samples

Question 15

What are the limitations of using Y chromosomes ?

Answer 15

-lack of individuality: shared among male relatives
-limited genetic diversity compared to autosomal markers

Question 16

What is the difference in lineage markers ?

Answer 16

Autosomal- passed on in part from all ancestors
Y-chromosome- passed on complete but only by sons
Mitochondrial- passed on complete but only by daughters

Question 17

What is LMD (laser micro-dissection)

Answer 17

-isolates sperm cells from microscope slides
-allowing re-analysis
-effectively separates sperm from mixed cell types without loss of male material

Question 18

What is LCN an extension of ?

Answer 18

SGM plus (10 autosomal loci + sex marker)

Question 19

What are the different techniques used in LCN ?

Answer 19

-increased PCR cycles
-enhanced detection methods

Question 20

What are the PCR cycles increased to in LCN ?

Answer 20

From 28-30 to 34-35

Question 21

What are limitations of LCN ?

Answer 21

-require careful handling to avoid contamination
-increased risk of contamination can lead to false positives
-incorrect or misleading results can complicate interpretation

Question 22

What are common biological fluids in forensics ?

Answer 22

-blood
-saliva
-semen
-vaginal secretions
-urine

Question 23

What are the identification methods for biological fluids ?

Answer 23

-immunological tests/ chemical tests
-molecular methods
-RNA-Based methods

Question 24

What are spectroscopic techniques of bodily fluid analysis ?

Answer 24

-Raman Spectroscopy: Analyses light scattering to create complex spectra for fluid identification; variability observed with aging bloodstains.
-Fourier Transform Infrared (FT-IR) Spectroscopy: Evaluates biological fluids while accounting for environmental contamination.

Question 25

What are emerging technologies of bodily fluid analysis ?

Answer 25

-DNA Methylation Patterns: Examines methylation at specific genomic sites to identify tissue origin and estimate age.
-Microbiome Analysis: Studies microbial communities to provide additional context in forensic investigations.

Question 26

What are the principles of DNA phenotyping ?

Answer 26

Involves analysing genetic information to predict physical traits and ancestry from biological samples, such as hair, saliva or blood

Question 27

What does the process of DNA phenotyping use ?

Answer 27

Specific genetic markers associated with traits like eye colour, hair colour and skin pigmentation

Question 28

What are the limitations of genetic phenotyping ?

Answer 28

-DNA phenotyping cannot provide definitive identification; it narrows down possibilities rather than pinpointing a specific individual.
-Environmental factors and gene interactions can influence physical traits, leading to uncertainty in predictions.

Question 29

What are the ethical considerations of DNA phenotyping ?

Answer 29

-Potential misuse of genetic information for profiling individuals based on appearance.
-Concerns about privacy and consent when using genetic data for non-medical purposes.
-Regulatory frameworks vary by country; some nations have strict guidelines on the use of DNA phenotyping in forensic investigations.

Question 30

What is the current application of DNA phenotyping ?

Answer 30

Used in criminal investigations to generate leads when traditional DNA profiling does not yield results and assists law enforcement in narrowing down suspect list

Question 31

What is the future potential for DNA phenotyping ?

Answer 31

-Advances in genomic research may improve accuracy and expand the range of predictable traits.
-Integration with other forensic techniques could enhance investigative capabilities.