Question | Answer |
Sequence Distribution | Sequences of most eukaryotic genomes based on how many times they are repeated
Highly repetitive sequences
Intermediate sequences
Rare sequences |
Highly repetitive sequences | Up to a million copies of per genome
3%
Structural, not functional |
Intermediate Sequences | hundreds-thousands per genome
>45%
Mostly degenerate retrotranspoons
Viruses |
Rare Sequences | >50%
Most functional genes belong to this class |
Total base pairs in the human genome | 3.2 billion
Base pairs per chromosomes
45-280 million |
Fraction of genome transcribed into RNA | 1/3 |
Percent of genome that encodes protein | 5% |
Estimated number of genes | 31,000 |
Transposons | Jumping Genes
Sequences capable of moving from one location in the genome to another.
Viruses that lost their ability to jump between cells |
Retroviruses | RNA Viruses
Parasitic DNA molecules capable of moving from one cell to another with the use of an RNA intermediate. |
Retrotransposons | Transposons that move through RNA intermediates.
DNA sequences are transcribed into RNA which is then reversed transcribed back into DNA to be reinserted into a chromosome. |
Recognition sequences | Marks regions of a chromosome.
They are recognized and bound by specific proteins |
Sequence Analysis | Computer looks for regions that are very similar and lines them up on that similarity. |
Most common retrotransposon sequence | Alu |
Functional Intermediate Class Genes | tRNA
rRNA
Histones
(housekeeper genes) |
Gene Families | genes with similar, not identical sequences.
Not restricted to a single genome.
Can be from different organisms |
Clustered gene families | clusters differ from the tandem repeats of the repetitive class because the sequences are not identical, they are not as contiguous, and the genes are not necessarily oriented in the same direction. |
Psuedogenes | Genomic sequences similar to expressed genes, but which have been mutated so they no longer express a gene product. |
Globins | Globins are subunits of hemoglobin, the protein that transports O2 and CO2 through the blood. |
Hereditary persistence of fetal hemoglobin (HPFH) | a clinical condition where fetal globin expression persists throughout life. |
Thalassemias | defective alpha or beta globins |
Histones | All five histones are homologous to each other, so they represent a gene family |
Most homologous gene family known | Histones |