Week 3 - genomics and bioinformatics Flashcards
What is a Genome?
All the genetic material of an organism
How does the complexity of an organism relate to it’s genome size?
Genome size doesn’t increase with organism complexity- because of junk DNA, 66% of genome is repetitive sequences.
How can eukaryotic genomes produce more than 1 protein per gene ?
Due to alternative splicing of RNA transcripts (mixing and matching of different exons)
How do the number of genes influence genome size?
Genome size doesn’t mean more genes
What 3 elements make up the eukaryotic genome?
- Protein-coding genes
- Non-protein-coding DNA
- Repetitive sequences
What makes up protein coding genes?
Exons, introns and regulatory sequences (like promoters)
What is the function of noncoding DNA in the genome?
Its non-repetitive DNA that mostly codes for RNA genes.
These RNA genes can be non-coding nc(RNA) - so they don’t code for a protein but have other functions like rRNA and tRNA.
What does ncRNA stand for? Give an example of small ncRNA and a function for Long ncRNA
Non-coding RNA, small ncRNA = tRNA and long ncRNA regulates gene expression
What are the 2 types of repetitive sequences in the eukaryotic genome?
- Repeated sequences [unrelated to Transposable elements]
- Repeated sequences [related to Transposable elements]
What is meant by repeated sequences unrelated to transposable elements? Give an example
They are sequences not caused by “jumping genes” just natural repeats, next to each other (tandem repeats).
Example:
Minisatellites (repeats of 10-60 bp)
Microsatellite (less than 10 bp)
What causes repeated sequences unrelated to transposable elements ?
Strand slippage during DNA replication
What are microsatellites?
Are less than 10 bp, often referred to as short tandem repeats (STRs) or simple sequence repeats (SSRs). Are unrelated to transposable elements
What is meant by repeated sequences related to transposable elements?
Are repeats of DNA that come from or are part of transposable elements that copied themselves around the genome.
Where did the repetitive sequences related to transposable elements come from ?
They came from viruses or transposable elements that inserted copies of themselves into different parts of the DNA
What are transposons ?
Pieces of DNA that can move around in the genome (jumping genes)
What are the 2 types of transposable elements?
DNA Transposons and RNA Transposons
How do DNA transposons move?
Cut and paste method:
The transposon is cut out of one spot and inserted into another- require a transposase enzyme.
How do RNA transposons move?
Copy and paste method:
1. They’re transcribed into RNA
2. Then turned back into DNA (by reverse transcriptase)
3. New DNA copy is inserted elsewhere in the genome
Original stays so number repeats increases
Which vegetable is related to the discovery of Transposons ?
Indian corn (Barbara McClintock’s breeding research).
How did corn kernels show evidence of jumping genes?
The jumping of genes caused a break down of colour genes in corn (when gene was re-inserted - disrupted colour gene)
What are Alu elements?
Most abundant gene in the human genome, most don’t do anything.
They make up a large portion of RNA transposons
How can transposons impact genome evolution?
Multiple copies of similar transposable elements may facilitate recombination between different chromosome
What is junk/selfish DNA ?
Noncoding DNA that has no function
What is the definition of epigenetics?
Heritable changes of genetic information not caused by changes in the DNA sequence
