DNA Structure AHL

IB Biology HL

Outcomes

• 7.1.1 Describe the structure of DNA, including the antiparallel strands, 3’–5’ linkages and hydrogen bonding between purines and pyrimidines.

• 7.1.2 Outline the structure of nucleosomes.

• 7.1.3 State that nucleosomes help to supercoil chromosomes and help to regulate transcription.

• 7.1.4 Distinguish between unique or single-copy genes and highly repetitive sequences in nuclear DNA.

• 7.1.5 State that eukaryotic genes can contain exons and introns.

A Crash course in DNA

structure and replication

• http://www.youtube.com/watch?feature=player_e

mbedded&v=8kK2zwjRV0M

Nucleotide Structure and Base

Pair Hydrogen Bonding

DNA Structure in detail

• http://www.johnkyrk.com/DNAanatomy.html

Nucleosomes Nucleosome Function

• Nucleosomes are DNA wrapped around histone

proteins with other associated proteins to regulate

supercoiling

• Nucleosomes help to supercoil chromosomes and

help to regulate transcription.

7.1.4 Distinguish between unique or single-copy

genes and highly repetitive sequences in nuclear

DNA.

• Single Copy genes are regions of the DNA that code

for a specific polypeptide

• Highly repetitive sequences are also known as

satellite DNA. They are not expressed and do not

affect your appearance or the functioning of your

proteins. They are used in DNA fingerprinting

because they accumulate mutations easily.

Introns and Exons

• 7.1.5 State that eukaryotic genes can contain exons

and introns.

• Introns will be removed from the mRNA and they

will stay in the nucleus so they are not translated and

will not impact the protein that is made.

• Exons are coding regions of mRNA that will be used

as a guide to build proteins

Animation

• http://www.four-

h.purdue.edu/apple_genomics/flash/movie3.swf

A DNA Game!

• http://www.nobelprize.org/educational/medicine/

dna_double_helix/index.html