Construct appropriate representations to model and compare the forms in which DNA exists in eukaryotes and prokaryotes (ACSBL076)

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Comparison between Eukaryotic and Prokaryotic DNA


Feature Prokaryotic DNA Eukaryotic DNA
1. Location Freely found in cytoplasm in a region called nucleoid. Is contained within a membrane bound nucleus.
2. Packaging Are not bounded with histone proteins and thus DNA does not form tightly coiled structures. DNA is bound to histone and non-histone proteins that helps the DNA to form a tightly coiled and packed structure so that a large amount of DNA can reside in the nucleus.
3. Shape of Chromosome Chromosomes are circular in shape and can form loops since they are not tightly packed. Chromosomes are linear.
4. Genome Compact and contains very little repetitive DNA and no introns. Contains large amounts of repetitive DNA and intron.
5. Chromosome Number Have only one principal chromosome which may have multiple copies. Contains variant number of chromosomes depending on the type of organism.
6. Number of Nucleotide Base Pair Ranges from 160, 000 to 12.2 million. Can vary depending on the type of organism. For example, humans have 23 pairs of chromosomes containing about 2.9 billion base pairs.
7. Replication Process Relatively simple and speedy (2000 base pairs/second) and during the process only a single origin, replication fork and bubble is formed. Prokaryotic Replication takes about two proteins to initiate. Is more complex and slower (100 base pairs/second) and during the process, multiple origins, replication forks and bubbles can be formed. Takes about multiple protein sub units to initiate.
8. Presence of extra- chromosomal DNA Contains extra chromosomal DNA known as plasmid. Does not contain plasmid but different cell organelles such as mitochondria and chloroplast have their own DNA.
9. Information Content Prokaryotic DNA is organized in segments called operons which code for multiple proteins. Eukaryotic DNA contains genes and each gene codes for a single protein. Sometimes, multiple genes can code for the same protein as well.

Note: Introns are sequences of DNA which do not code for protein.

Extract from HSC Biology Stage 6 Syllabus. © 2017 Board of Studies NSW.