Genomes, Transcriptomes, Proteomes

Question 1

What is a genome?

Answer 1

• 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

Question 2

Where is the genome found in eukaryotes?

Answer 2

In chromosomes in the:

• Nucleus
• Mitochondria
• Chloroplasts

Question 3

How does genome size differ between organisms?

Answer 3

• 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

Question 4

Why does genome size differ with body size?

Answer 4

• 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

Question 5

What information can be gained from genomes?

Answer 5

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

Question 6

What is a telomere?

Answer 6

• 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

Question 7

How is a nuclear genome organised?

Answer 7

• Centromere in the middle
• Surrounded by satellite DNA
• Telomeres at ends
  Zoom
• Transposable element
• Intergenic region
• Regulatory sequence
• Transcribed region
• Regulatory sequence

Question 8

What is in a mammalian chromosome

Answer 8

• Repetitive DNA
• Ribosomal DNA
• Telomeres
• Centromeres
• Up to 98% of DNA sequences are untranscribed
• Natural selection would retain important information

Question 9

What are mini satellites?

Answer 9

300bp sequences that are repeated

Question 10

What are micro satellites?

Answer 10

2-3bp units which are repeated

Question 11

What are transposable elements?

Answer 11

• 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

Question 12

What is a point substitution mutation?

Answer 12

• 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

Question 13

What is an insertion mutation?

Answer 13

• Extra bases inserted
• Frame shift
• Gene will probably be switched off

Question 14

What is a deletion mutation?

Answer 14

• One base deleted

- Frame shift

Question 15

What is PCR

Answer 15

• Polymerase Chain Reaction

- Allows production of any amount of a known DNA sequence

Question 16

What are primers?

Answer 16

Specifically designed oligonucleotides to match DNA around gene of interest

Question 17

What happens during PCR?

Answer 17

• 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

Question 18

What can we do with PCR?

Answer 18

• Amplify microsatellites
• Amplify genes from particular animals for sequencing
• Amplify genes across species
• Amplify ancient/degraded DNA
• Amplify from minute samples

Question 19

What can be determined by amplifying micro satellites?

Answer 19

• Used as molecular markers in genetics: paternity, forensics
• Used to genotype individuals

Question 20

What is PCR DNA sequencing?

Answer 20

• 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

Question 21

What are transcriptomes?

Answer 21

• The set of RNA molecules produced by an organism, organ or group of cells
• Defines the genes that are being expressed