lecture 22 - human genome Flashcards
What were the aims of the 1990 human genome project?
Identify all human genes and their roles, and analyse genetic variation between humans and other species.
How many base pairs are found in nuclear DNA?
6 billion
How many genes are found in the human genome?
Approximately 20,000
What is the structure of mitochondrial DNA?
Single stranded, circular
How many base pairs are found in mitochondrial DNA?
approx. 16500
Where is mitochondrial DNA inherited from?
The mother exclusively
How many genes are found on mitochondrial DNA?
37
What percentage of genes code for proteins?
<2%
What percentage of genes are coding (exons)?
<2%
What percentage of the DNA sequence is introns (non-coding segments)?
20%
What percentage of the human genome has unknown function?
20%
What does SNPs stand for?
Single Nucleotide Polymorphisms.
What are SNPs?
Nucleotide sites that commonly vary within populations.
What distinguishes an SNP from a mutation?
If a particular combination has more than 1% prevalence in the population, it is considered at SNP.
What is the prevalence of SNPs in the human genome?
1 in 300 base pairs.
Where do SNPs mainly originate from?
Inheritance from parents, as opposed to just mutation.
What is a linked SNP?
An SNP that is outside a gene, and has no effect on protein production or function.
What are causative SNPs?
SNPs found in a gene.
What are non-coding SNPs?
causative SNPs of a gene that change the amount of proteins produced.
What are coding SNPs?
Causative SNPs that change amino acid sequence, and therefore the protein coded for by the gene.
Why is there greatest genetic variation in the African Continent, compared to the rest of the world?
The rest of the world’s populations evolved from a bottle-neck population that migrated from Africa - the ‘founder effect.’
What does STRs stand for?
Short Tandem Repeats
What are STR?
repeats of 2-5 nucleotides, found in specific regions of the genome. In each allele, there are many different possible numbers of repeats possible. You may inherit an allele with a different number from each parent.
What are InDels?
Small insertions or deletions in DNA that can cause ‘frame shift’ which changes the way DNA is read in protein coding regions.
What does CNVs stand for?
copy number variations
What are CNVs?
Chunks of DNA greater than 500 base pairs long that are present at different amounts or ‘copy numbers’ relative to a reference
genome. (More or fewer of a certain type of segment).
How many CNVs do humans have?
10,000 within and between genes.
Are CNVs exclusive to single genes?
No - they can span multiple genes.
The human genome project showed that what percentage of genes code for proteins?
Less than 2%
