Forensic Biology Midterm

Compared to the hydrolysis probe qPCR method, qPCR that uses SYBR Green intercalating dye is advantageous because?

The assay design is simple and little optimization is requried

The RSID-Blood test detects what?

Human Glycophorin A

Compared to the hydrolysis probe qPCR method, qPCR that uses SYBR Green intercalating dye is advantageous because?

The assay design is simple and little optimization is requried

The RSID-Blood test detects what?

Human Glycophorin A

Kastle Meyer Test uses hydrogen peroxide and what?

Phenolphthalein

RSID-Semen test detects what?

Seminogelin

What does DTT do?

A reducing agent that breaks down disulfide bonds

What is the purpose of Chaotropic salt in solid phase extraction?

It dehydrates DNA and facilitates binding of the DNA to the silica membrane or silica-coated magnetic bead through a salt bridge.

What are the steps of organic extraction summarized?

Cell Lysis, Centrifuge, Transfer supernatant to a new tube, addition of phenol and chloroform, Centrifuge, removal of aqueous phase to a new tube, ethanol precipitation, purified DNA collected, and released in a protective buffer.

What is FTA paper?

an absorbent cellulose-based paper that contains four chemical substances to protect DNA molecules from
nuclease degradation and preserve the paper from bacterial growth.

What does Chelex do?

tightly binds all the Mg²⁺ in the extract, preventing DNA degredation

Which sample is processed first? The Q or the K?

The Q (Questioned) Sample is always processed first

Is DNA negatively charged or positively charged?

negatively charged

How does the Phadebas test work?

Active ingredient is Starch Polymer chains interlinked to form a sphere
The Sphere is insoluble in water, the dye inside it is water soluble
When in contact with amylase, DSM is degraded and dye is relased

What is the best way to confirm the presence of spermatoza?

Microscopy is the best way to confirm the presence

Who invented the term DNA fingerprinting?

Sir Alec Jefferys

Proteins absorb light at what wavelength

280 nm

What is not a benefit of presumptive test?

They can conclusively identify a biological fluid

What enzyme in saliva is detected by the Phadebas test?

Alpha-amylase

Which of the following is not a general purpose required of all DNA extraction methods?

Separation of Male and Female Components of Cellular mictures

What is the purpose of SDS in a DNA Extraction?

SDS is ionic detergent used to break down the lipids in cell membrane

Chelex protects DNA during the extracting process because

It binds to metal ions, such as magnesium, which are necessary for nuclease activation.

What would happen if you forgot to add your chaotropic salt to the lysis buffer in a solid phase extraction.

The DNA backbone will not bind to the silica-column, causing the DNA to be in the flow through.

Why do we quantify our DNA?

To know the exact amount of DNA that is going into amplification. High levels of DNA create more artifact peaks and low levels of DNA produce allele dropout. It has to be 1 ng

A qPCR method that uses hydrolysis probes to detect each new strand of DNA is called the __________ assay.

Taqman

What are the stages of DNA profiling?

Extraction, Quantitation, Amplification, Separation, and Analysis

What does the Quantifiler Trio DNA Quantification Kit Include?

Large autosomal target, Small autosomal target, Y-chromosomal target, IPC, NTC

What is IPC?

IPC stands for Internal Positve Control. It is a short strand of DNA that is amplified in the reaction of the DNA sample.

Why is IPC used?

Its used to assess the quality of the sample

How is IPC used?

If the IPC DNA amplifies but the sample does not, it can indicate a low amount or no starting template. If the IPC DNA and sample DNA both fail to amplify, it indicates inhibition of the PCR.

What is another way that IPC can be compared to indicate some level of inhibition?

it can be compared to the CT of the IPC to the CT of the NTC. If there is a reduced CT of the IPC, it can indicate some level of inhibition.

How is DNA degradation assessed?

DNA degradation is assesses by comparing the ratio of long target amplification to small target amplification in the assay.

What is the degradation index?

small autosomal target concentration / large autosomal target concentration