B1.2, D1.1, D1.2 IB BIO HL1

What enzyme unwinds the DNA helix during replication?

Helicase

Put the steps of DNA replication in order: Helicase unwinds DNA, Primase adds primers, DNA polymerase III synthesizes new strands, Polymerase I replaces RNA primers, Ligase seals gaps.

Helicase → Primase → DNA polymerase III → Polymerase I → Ligase

True or False: DNA ligase removes RNA primers.

False (DNA polymerase I removes RNA primers; ligase seals gaps)

What is the function of RNA polymerase in transcription?

It unwinds DNA and synthesizes mRNA using complementary base pairing.

In which direction is mRNA synthesized?

5' to 3'

What happens in the P site of the ribosome during translation?

The tRNA holds the growing amino acid chain, which links to the new amino acid from the A site.

Define semi-conservative replication.

DNA replication where each new molecule has one original strand and one new strand.

Match each protein structure with its description: Primary, Secondary, Tertiary, Quaternary.

Primary - Sequence of amino acids. Secondary - Alpha helices and beta sheets. Tertiary - 3D shape of a polypeptide. Quaternary - Multiple polypeptides interacting.

How does gel electrophoresis separate DNA fragments?

By size—smaller fragments move faster through the gel.

List two uses of DNA profiling.

Forensics and paternity testing.

What is the difference between coding and noncoding DNA?

Coding DNA contains genes for proteins, while noncoding DNA does not but may have regulatory functions.

Which RNA type carries amino acids to the ribosome?

tRNA

Identify the amino acid: It has an imidazole group in its R group.

Histidine

What type of reaction forms peptide bonds between amino acids?

Condensation reaction

What is the role of proteasomes in translation?

They break down unneeded proteins into amino acids for reuse.

Where does tRNA enter the ribosome?

A site

What type of protein is insulin?

Globular

What is the purpose of PCR in DNA profiling?

To amplify small DNA samples for analysis.