L3 The Human Genome Flashcards
What is the function of DNA?
Encode all info required to make an organism (DNA to RNA to protein)
It must replicate itself accurately
It must allow beneficial mutations to be selected
Human Genome Stats [4]
• 3.2 billion (3,200,000,000) bases of DNA (3.2 x109)
○ ~50% high-copy repetitive elements
• 1.5% protein coding & 80% functional
20,000-25,000 genes
What is the extent of variation? [3]
• Genes 99.9% identical
Each have ~3 million single nucleotide polymorphisms (SNP)
Each have ~50-100 SNPs associated with an inherited disease. Healthy as we’re diploid: two copies of each gene
Functional genomics [4]
Mechanisms of disease
Targeted therapeutic/gene therapy
Human evolution
The Lab
Personalised medicine
Predictive
Pharmacogentics (warfarine metabolism cyp2c9 - 40% drugs prescribed have no effect)
Ethics
Nucleotide - what does it consist of?
Nitrogen containing base, 5 carbon sugar and 1 or more phosphate group
What is a Pyrimidine?
Cytosine
Thymine
What is a Purine?
Guanine
Adenine
What do Phosphodiester bonds do?
Links nucleotides
What are the levels of DNA folding?
Short DNA region -> chromatin -> chromatin fiber packed into nucleosomes -> chromatin fiber folded into loops -> mitotic chromosomes
What does the core particle consist of?
8 histones (octamer) 2x H2A, H2B, H3 and H4
H3 tail
What is the charges of a nucleosome?
Histone +ve, DNA -ve
What is the second level folding?
H1 for 30nm
Supercoiling - what problems can it cause?
β-globin: severe anaemia
Tumour suppressor genes: cancer
Epigenetics - what is the definition?
heritable changes in gene function that cannot be explained by changes in DNA sequence
