DENT LECTURE 9 The Eukaryotic Genome.pdf

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19 Apr 2012
Tetraploids are big. It not because they have more cells, but mostly because their cells are bigger.
Reptiles have lots of DNA where as birds have relatively little DNA
Size of dinosaur cells are smaller than that of reptiles
t-Rex have relatively little DNA, making them more closely related to birds than to reptiles.
Dinosaurs compared to birds and reptiles:
Cell size may be used to estimate genome size…
In eukaryotic DNA, there seemed to be a lot more DNA than was needed for the genes that needed to
be encoded.
In prokaryotic DNA, genes are packed in like sardines with basically just enough room between them
for a promoter and maybe an operator.
If there is a simple linear relationship between genome size and amount of DNA and humans have 30
times as much DNA as roundworms, then they should have 30x as many genes = ~600,000 genes. In
fact humans have ~30,000 genes.
Humans have way more DNA than they need to encode all of their proteins!
What's with all the extra DNA? (eukaryote specific; prokaryotes don't do this…)
There are big gaps of DNA that don't encode for any of the protein sequence.
All DNA are transcribed into primary RNA transcript, which includes introns (the non-coding sequences
in eukaryotic genes), and exons (coding gene sequences for protein)
The RNA that is transcribed from the gene is processed to produce the final mRNA that is translated:
RNA processing: splicing.
Comparative genomics
Genomes have different sizes, not just
because they have diff. number of
chromosomes, but the absolute size of
genomes change.
Cells are bigger when they have more DNA
DENT LECTURE 9: The Eukaryotic Genome
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