Genomes, Transcriptomes, Proteomes Flashcards
What is a genome?
- The sum of the genetic information contained within an organism
- Influences nearly every character of an organism
- Give insight into evolution: chimpanzees and humans share 98% of genome
Where is the genome found in eukaryotes?
In chromosomes in the:
- Nucleus
- Mitochondria
- Chloroplasts
How does genome size differ between organisms?
- Genomes of simple organisms are small and dense
- More complex organisms have more DNA, more genes and more untranslated regions
- Genome size goes up with body size
Why does genome size differ with body size?
- In small organisms their genetic machinery is expansive compared to the rest of the organism
- Thus the genetic material has to be economised
- Therefore there are fewer, more compact genes
- In larger organisms the number of genes goes up but density goes down
What information can be gained from genomes?
Mitochondrial Genome
- Genome evolves quickly
- Polymerase not as effective so makes more mistakes
- Site of respiration so lots of oxidative stress which causes mutations
- Can be used for short term evolutionary studies
Nuclear Genome
- Evolves more slowly
- Can be used for long term evolutionary studies
- Same genes present in different species can be compared
- Can understand gene function
What is a telomere?
- A series of repeats where the microfibres attach to pull to different pole
- Get shorter as you age
- Main reason for again as cannot undergo mitosis any more
How is a nuclear genome organised?
- Centromere in the middle
- Surrounded by satellite DNA
- Telomeres at ends
Zoom - Transposable element
- Intergenic region
- Regulatory sequence
- Transcribed region
- Regulatory sequence
What is in a mammalian chromosome
- Repetitive DNA
- Ribosomal DNA
- Telomeres
- Centromeres
- Up to 98% of DNA sequences are untranscribed
- Natural selection would retain important information
What are mini satellites?
300bp sequences that are repeated
What are micro satellites?
2-3bp units which are repeated
What are transposable elements?
- Code for enzymes recognise their own DNA sequence
- Cut them out and move them to another part of the chromosome
- Can move other genes with them
What is a point substitution mutation?
- One base change
- Change in amino acid
- If in the third codon position likely won’t make a difference
- If in the first codon position change is almost certain
What is an insertion mutation?
- Extra bases inserted
- Frame shift
- Gene will probably be switched off
What is a deletion mutation?
- One base deleted
- Frame shift
What is PCR
- Polymerase Chain Reaction
- Allows production of any amount of a known DNA sequence
What are primers?
Specifically designed oligonucleotides to match DNA around gene of interest
What happens during PCR?
- Primers are synthesised to anneal to flanking regions
- Heating to separate strands
- Cooling to allow primers to anneal
- DNA polymerase extends chain in a 3’ direction from the primers
- Heating and cooling: more primers bind etc.
- Multiple copies of target gene
What can we do with PCR?
- Amplify microsatellites
- Amplify genes from particular animals for sequencing
- Amplify genes across species
- Amplify ancient/degraded DNA
- Amplify from minute samples
What can be determined by amplifying micro satellites?
- Used as molecular markers in genetics: paternity, forensics
- Used to genotype individuals
What is PCR DNA sequencing?
- Uses DNA replication terminating chemicals in four separate reactions each stopping at a particular base
- A photodetector can be used to read colours or a gel can be used
What are transcriptomes?
- The set of RNA molecules produced by an organism, organ or group of cells
- Defines the genes that are being expressed
