Genomes
- Created by: Alice Fisher
- Created on: 05-05-15 14:13
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- Genomes
- Nucleus of eukaryotic cell contains its chromosomes and is surrounded by a porous envelope
- Different cell types have different transcriptomes and proteomes
- Each human somatic cell contains 2 copes of each of the 21000 protein coding genes
- Definitions
- Telomere; Specialised DNA sequence at the end of linear chromosomes which maintain chromosomal integrity. Painted by telomerase
- Contromere; part of a chromosome that links sister chromatids. Where the kinetochore assembles
- Replication origin; DNA sequence where replication is initiated
- Kinetochore
- Each kinetochore forms a plaque on the surface of the centromere. Their plus ends are embedded on to microtubules which form the spindle
- Attachement site to microtubules contains a protein collar holding it tightly while still allowing polymerisation and depolymerisation
- Each kinetochore forms a plaque on the surface of the centromere. Their plus ends are embedded on to microtubules which form the spindle
- Replication
- When both strands separated seen as a 'replication bubble'
- When replication fork reaches end of linear chromosome there is no place to produce the RNA primer needed for last fragment at tip
- Bacteria solve by having circular DNA and replicate in bidirectional fashion
- Eucaryotes use telomeres to elongate tip in 5' 3' direction using an RNA template. After this extension, DNA polymerase can continue.
- Genes
- More complex organisms have lager genomes and genome increases as gene numbers does
- Gene density declines as organisms becomes more complex. Internecine distances increase.
- More complex organisms have similar exon sizes but more larger introns
- E.g pufferfish Hungtingtin gene 7.5x larger than human equivalent due to larger introns (eons the same)
- 1.5% of human genome is protein coding. 50% is repeated DNA sequences
- The rest is evolutionary conserved
- More complex organisms have lager genomes and genome increases as gene numbers does
- Nucleus of eukaryotic cell contains its chromosomes and is surrounded by a porous envelope
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