DNA profiling VCE Biology 3/4

Unit 3 AOS 1

DNA profiling

Identifying an individual using their genetic information.

Give three uses of DNA profiling.

Paternity testing, crime-scene analysis, and identifying human remains.

What are short tandem repeats (STRs)?

Short sequences of nucleotides repeated multiple times in non-coding DNA between genes.

How long are the repeated units in STRs in the notes?

Typically 2–7 bases per repeat unit.

Why are STRs useful in DNA profiling?

The number of repeats, and therefore STR length, varies greatly between individuals.

How many STRs exist in the human genome, and how many are commonly used in profiling?

Thousands exist; 13 are commonly used in the notes.

How are STR regions amplified for DNA profiling?

PCR with specific primers is used to isolate and amplify each STR.

How are STR fragments separated to determine their length?

By gel electrophoresis.

What does a heterozygous individual show for an STR?

Two bands, representing two different STR lengths.

What does a homozygous individual show for an STR?

One band, because both copies have the same STR length.

How is a DNA profile compared between samples?

Compare the banding patterns across the STRs analysed.

What did the crime-scene example conclude?

Blood from the victim and suspect 2 was found at the scene; suspects 1 and 3 matched each other, possibly as identical twins.

What is one social benefit of DNA profiling?

It can help identify and convict perpetrators of crimes.

What is one ethical benefit of DNA profiling?

It can determine parental lineage or identify deceased people for family closure and burial.

What social questions can DNA profiling raise?

Which organisations can access genetic data, and who owns that data?

What ethical or privacy concerns can DNA profiling raise?

People may object to DNA sequencing, and personal genetic data may be leaked.