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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