Year 12 ATAR Biology

Summary:

This note provides an overview of the Year 12 ATAR Biology curriculum for Units 3 and 4.

Excerpt:

Biology

Biotechnology:
Biotechnology or biotechnological techniques are methods scientists use to identify, manipulate, compare, and use genetic information. We will break biotech into the following areas:
1. Cutting DNA
2. Recombining DNA
3. Amplifying DNA
4. Visualising DNA
5. Sequencing DNA

The direct link between genetic information and phenotypes; all phenotypes are based on genes

Cutting DNA:
To be able to genetically engineer organisms, and manipulate genes present in organisms, we need to be able to isolate/remove specific genes. Isolating or removing genes is done with specific biotechnological tools called restriction enzymes or restriction endonucleases. Restriction enzymes cut DNA at specific sequences called restriction sites; the removed fragment is called a restriction fragment and contains the desired gene.

A restriction fragment can have two shapes; either defined as:
1. Blunt
2. With sticky ends

Blunt fragments do not have exposed nucleotides and are harder to anneal or recombine into host DNA.

No natural attraction.

Sticky ends have exposed nucleotides on each end of the fragment; ensure that they can easily be recombined. Nucleotides have a natural attraction to complementary nucleotides.

Recombining DNA:
The desired gene is then inserted into a host genome; the same restriction enzyme is used to create a space for the desired gene to be inserted. The fragment type affects the efficiency of the process, yet DNA ligase is used to seal the new/modified DNA to ensure the gene is inserted (recombinant DNA technology). Recombinant DNA involves both cutting the DNA and DNA ligase.

Primers:
Short, single-stranded DNA molecules are used in a DNA technique called PCR. In PCR DNA is synthesized using special DNA polymerase enzymes in a step called extension. Polymerase enzymes do not know where to start extending by themselves; primers are used to mark the two ends of a target sequence.

The primer sequence of nucleotides is complementary to specific sequences of DNA at either end of the target
sequence. Primers join at the 3’ end of the template strand, enabling extension/synthesis to be in a 5’ to 3’ direction. Primer for initiating synthesis in DNA replication is made out of RNA.