Theme 3 - human genome Flashcards
what type of chromatin predominates in the nucleus
euchromatin
where is ribosomal RNA translated
nucleolus
how is information trafficked in and out of the nucleus
via pore on the envelope
what are the three functions of DNA
encode all information required to make an organism, replicate accurately and must allow for beneficial mutations to be selected (for evolution)
what is the definition of genetics
study of heredity - process by which characteristics are passed from parent to offspring
what is a gene
unit of biological information that encodes a specific protein or regulatory molecule
what is precision medicine
new approach to treatment that takes into account individual variability in genes, environment and lifestyle
when was the first human genome published?
2001
how long did first genome sequencing take and how much did it cost
13 years and cost 3 billion dollars
how much does genome sequencing now cost and how long does it take
takes a few days and costs $5000
how many bases make up DNA and what % of these are repeated sequences?
3.2 billion bases and 50% of this is repeated
what % of DNA is protein coding?
1.5%
how many genes does the genome contain and how many of these are essential for life?
contains 20,000 genes and 300-400 of these are essential for life
what gives genes complexity?
spatial and temporal regulation
what % are genes identical?
99.9%
how many SNPs do we have in the genome?
3 million
around how many disease associated SNPs does each individual have?
50-100
give two reasons why a SNP may not cause disease?
we are diploid and therefore have two copies of each gene or the SNP doesn’t cause change to the protein
what is polygenic disease and give an example
multifactorial disease eg environment and genes together for example CVD
what drug does highly active cyp2C9 affect?
warfarin - high levels of cyp2c9 will metabolise warfarin faster
what % of prescribed drugs have no effect?
40%
what three things make up a nucleotide?
sugar, phosphate and a base
what bonds are made between complementary base pairs?
weak hydrogen bonds
what is the bonding in the backbone of DNA?
strong covalent
which type of bond links nucleotides together to make a polar molecule
phosphodiester bonds
what are the five steps of supercoiling DNA into a mitotic chromosome?
2nm short region of DNA, beads on a string chromatin 11nm, chromatin packed into a nucleosome 30nm, chromatin fibres folded into loops 700nm, entire mitotic chromosome 1400nm
what state nm state is chromatin in most of the time?
30nm
what is the first level of DNA folding?
DNA folded round core histones to form a nucleosome
how many nucleotide pairs of DNA are found in one histone?
200
what charge to histones have?
positive
what does the second level of DNA folding require?
an extra histone - H1
what are the regular histone proteins required for folding
H2A, H2B, H3 and H4
what histone is required to make the 30nm fibre?
H1
what two methods regulate condensed chromatin to de condensed chromatin?
chromatin remodelling complexes and histone modifying enzymes
what are chromatin remodelling complexes dependent on?
ATP
how do histone modifying enzymes work?
they change the structure of the histones by addition or removal of acetyl/phosphate or methyl groups
what does supercoiling of the beta globing gene lead to?
severe anemia
what are heritable changes in gene function that cannot be explained by changes in a DNA sequence?
epigenetic
how can rubenstein taybi syndrome be characterised?
mutation in histone acetyl transferases which leads to non specific symptoms - mental retardation, facial abnormalities, broad thumbs and big toes
what is the incidence of rubenstein taybi syndrome?
1 in 100,000
