A1:2 Biology SL/HL

This is for IBDP Biology SL/HL students in the new curriculum (2025)

Where is DNA found?

Chromosomes of the nucleus (and certain organelles, chloroplasts, and mitochondria)

Where is RNA found?

Some is found in the nucleus, but most is found in the cytoplasm (particularly in the ribosomes)

What does the nucleotide consist of?

Nitrogenous base (C,G,A,T), pentose sugar, and a phosphate group

How are the components of the nucleotide combined?

Through an enzyme-controlled condensation reaction

When does a condensation reaction occur?

When two molecules combine, producing water as a byproduct

What are the ocular units calculations?

I = Size of image (mm), A = Actual size of the object (μm), M = magnification

Outline the three functional types of RNA

messenger RNA, transfer RNA, ribosomal RNA

What is the bond formed between adjacent nucleotides called in RNA?

3’-5’ phosphodiester bond

Why are the two strands in DNA called “antiparallel”?

because one runs from 5’ carbon to 3’ carbon and the other from 3’ carbon to 5’ carbon

What are homologous chromosomes?

Pairs of chromosomes (one from each parent) that carry the same sequence of genes

Outline the main differences between DNA and RNA

Double helix/single helix, deoxyribose/ribose, found only in living things/found in viruses

What is complementary base pairing?

The pairing of base pairs simply because they are the only ones that fit together on the helix. It allows genetic information to be replicated and expressed

What is transcription?

DNA is copied to make mRNA

What is translation?

when the message encoded in mRNA is read to form proteins