Genome Content and Organisation Flashcards
(15 cards)
What is a genome?
Entire DNA content of a cell, including genes and intergenic regions
Define transcriptome and proteome
Transcirptome: All mRNA transcripts in a cell
Proteome: All proteins encoded by the genome
Key facts about the human nuclear genome?
3.3 billion pase pairs
24 chromosomes (22 autosomes, 2 sex: X and Y)
2% protein-coding exons
20,000 genes
How does the mitochondrial genome differ from the human?
Circular, small (16,569 base pairs)
One chromosome - 10,000 copies per mitochondria
37 genes (13 protein-coding, 2 ribosomal RNA, 22 tRNA)
Do gene numbers correlate with organism complexity?
No - C -value paradox: genome size does not directly relate to genetic complexity
Gene numbers in model organisms? (Yeast, Nematode worm, Fly, Arabidopsis, Mammals)
Yeast - 6,000
Nematode worm - 21,700
Fly - 17,000
Arabidopsis - 25,000
Mammals - 20,000 - 25,000
What are the approximate contents of the human genome?
Exons - 2%
Introns - 24%
Large duplications - 5%
Simple repeats - 3%
Retrotransposons - 45%
Other intergenic DNA - 21%
What is repetitive DNA?
Sequences present in mutiple copies, often non-coding (centromeres, telomeres)
What is non-repative DNA?
Unique sequences, inlcuding protein-coding genes, RNA genes, gene clusters
What are gene families?
Sets of genes with similar function, arising via duplication (e.g., globin family)
What are pseudogenes?
Gene sequences that no longer produce functional proteins
Types of pseudogenes?
Processed: Formed via reverse transcription of mRNA
Non-processes: Result from gene duplication or mutations
What are highly repetitive vs. middle repetitive sequences?
Highly: 5-12 bp > 10⁶ copies
Middle: 50-300 bp, 10³–10⁵ copies
What is satellite DNA?
Tandem repeats adjacent to each other (e.g., alphoid DNA telomeres)
What is interspersed repetitive DNA?
Scattered repeats, including retrotransposones (LTRs, LINEs, SINEs)
