Processing DNA

What does PCR stand for?

Polymerase chain reaction

What does PCR do?

Enables small quantities of DNA to be replicated, producing testable amounts to use in analysis techniques.

What are the 3 steps of PCR?

1. denaturing

2. annealing

3. extension

What is thermocycling?

the process of repeatedly heating and cooling a material, device, or biological sample between set high and low temperature limits

How many ties is PCR approximately repeated?

20-30 times

Outline denaturation

• DNA sample reaches temperatures of 94-96°C

• hydrogen bonds holding two DNA strands together break

• seperates strands without disrupting each individual strand

Outline annealing

• DNA sample reduced to 50-60°C

• allows short strands of DNA (primers) to bind to the single DNA strands

• primers are complementary to either side of the section of DNA to be copied

Outline extension

• 72°C

• Taq polymerase is used to join new complementary nucleotides to the sections originating with the primers moving in 5’ to 3’ prime direction

What is gel electorphoresis?

a technique that is able to separate DNA strands based on their lengths.

Where are the DNA samples placed in gel electrophoresis?

in the wells

Where is the negative and positive electrode in gel electrophoresis?

Negative is closest to the DNA and positive is oppoisite; when electrical current passes through the gel the negatively charged DNA moves towards the positive electrode

Do smaller or larger DNA pieces move further?

Smaller

What is a DNA profile?

A technique that uses the banding patterns of DNA fragments as a means of identification; a DNA fingerprint is unique to a particular individual

Visualised when gel electrophoresis finishes.

What is the purpose of a DNA ladder?

The ladder contains segments of DNA with known lengths. The results from the unknown sample are compared to the ladder to determine the length of the DNA strands in the sample.

What is DNA sequencing?

The determination of the precise order of nucleotides in a sample of DNA.

What are the four nitrogenous bases for DNA?

• adenine

• cytosine

• guanine

• thymine

What happens to each nucleotide when DNA forms?

• each nucleotide loses two phosphate groups

• the sugar molecule loses a hydrogen atom from the hydroxy group (OH) when it bonds to the phosphate group of an adjacent nucleotide.

Whare the 4 ehtical consideration with genetic information?

• Autonomy: respect for the right to be self-determining and to choose whether or not to be tested and, if tested, to know and share the information. It also includes the right of an individual to decide their own future, independent of genetic information.

• Confidentiality: the use of genetic information is treated sensitively, and is accessed only by those who are authorised to access it.

• Equity: the right to fair and equal treatment regardless of genetic information.

• Privacy: the right to be ‘left alone’ and to make decisions regarding genetic testing and the resulting information, independent of others