Topic 7

Nucleic Acids and Proteins

DNA Structure

DNA Structure cont’d

DNA Replication

Organization of DNA in Eukaryotes

• Replication Initiation Sites

• Where the replication of DNA begins (may also be known as O.O.R.)

Nucleosomes• Globular structures that

contain 8 histone proteins, with DNA wrapped around 2 times

• Are connected to other nucleosomes by another histone protein (H1), known as a linker

• Essential for packaging DNA for mitosis/meiosis

• Involved in gene regulation

DNA Folding

DNA Folding

Repetitive Sequences

• Repetitive base sequences that are not translated

• Sometimes called satellite DNA• Sequences between 5-300 bp• May be repeated as much as 10,000x• Constitute 10-40% of euk. genomes• Function unknown• A vey small portion of euk. DNA is single

copy/unique genes

Introns and Exons