Genes, Genomes And Genomics 3 Flashcards
(17 cards)
What is repetitive DNA ?
It makes up 50% of the human genome
It is made of two classes:
1. Tandem repeats
2. Interspersed repeats
What are tandem repeats ?
Clusters of short repeated sequences
What are telomeres ?
Repetitive sequences at the end of the linear chromosome that protect the ends from degradation or tangling
Telocentric
Telomere next to centromere, so just one arm
Acrocentric
P is shorter than q
Metacentric
P and q are of equal length
What are other tandem repeats ?
- Minisatellites- occur at ends of the genome
- Microsatellites- occur throughout the genome
What are interspersed repeats ?
Longer sequences that are present in many copies dispersed throughout the genome
Examples:
1. DNA transposons
2. RNA transposons
3. LINE
4. SINE
5. LTR retrotransposons
What are the two types of transposition ?
- Cut and paste (non replicative)- DNA transposons
- Copy and paste (replicative)- retrotransposons
What are LINEs ?
Long interspersed nuclear elements
They transpose via an RNA intermediate which is then reversed transcribed
What are SINEs ?
Short interspersed nuclear elements
They use LINE machinery to retrotranspose
What is a pseudogene ?
A fragment of DNA that resembles a protein-coding gene but does not actually encode a protein
What are processed pseudogenes ?
They are created by retrotransposition, where an mRNA transcript is reverse transcribed and inserted back into the genome
What are unitary pseudogenes ?
They result from loss of function mutations
What are duplicated pseudogenes ?
Arise from gene duplication events
What is Sanger sequencing?
First generation sequencing
It is done by chain termination using dideoxynucleotides (ddNTPs)
What is next generation sequencing ?
Second generation sequencing- Millions of DNA fragments sequenced in parallel
Third generation sequencing- Nanopore sequencing
