Introduction to Genomics Flashcards
What is the role of genomics in healthcare?
Genomics has the potential to transform healthcare with more accurate diagnosis of a broader range of diseases with a genetic basis and allows patients to know their likelihood of developing one of these diseases.
What is genomics?
Structural and functional mapping of genomes and their evolutions.
What is a chromatin?
Consists of DNA and protein.
Found inside the nucleus of a cell, it is a bit of a ‘tangled mess’
What are histones?
Histones help package and regulate the DNA in the chromatin.
How many histones are there in a nucleosome?
8
What is DNA made up of?
A sugar called deoxyribose
How are the ‘rungs’ of the DNA ladder made?
Base pairs that weakly bond together to form these rungs.
They form a code which cells follow to make proteins
What are the two types of nucleotides?
Purines (base pairs AG)
Pyrimidines (base pairs TC)
What always pairs with A and what always pairs with G?
A always pairs with T (or U in RNA)
G always pairs with C
How is RNA made?
DNA holds a code which is used to make RNA through a process called transcription.
How does RNA make proteins?
Through a process called translation
How do amino acids know when to stop translating?
There is a ‘stop’ codon = UAG which stops the translation
How many amino acids are directly coded in the genome?
20 amino acids in the human body
What are the 4 characteristics of a protein?
Non-polar side chains
Polar side chains
Acidic side chains
Basic (alkali side chains)
What are the purpose of amino acids?
Amino acids do different ‘jobs’ in the final protein. If you change one of the amino acids in the sequence, then you could change the function of the protein.
How many genes do we have approximately?
~21,000
What are gene mutations?
Not all versions of a gene are the same, some genes will change causing mutations
What are the 4 types of gene mutations
Gain of function mutations
Loss of function mutations
Lethal mutations
Ineffective mutations
How does a single gene produce multiple proteins?
Through a process called alternative gene splicing
What are the two types of proteins?
Proteins have structural and functional types
What are some of the structural protein types?
Collagen
Elastin
Keratin
What are some of the functional protein types?
Enzymes
Ion channels
Neurotransmitter receptors
Antibodies
How do we changed the structure and function of a protein?
Through a process called translational modification
What are the 4 steps of translational modification?
- add carbohydrate parts
- add lipid parts
- modifying AA side chains
- Adding chemical regulators
What is a pseudogene?
Non-functional gene (‘damaged’ gene sequence)
What are the key features of pseudogenes?
They either do not produce proteins or it is non-functional
They lack key regulatory regions (e.g. missing introns or promoter)
They have a start codon but a premature stop codon
They may have a partially deleted gene sequence
What are the two types of sexual reproduction?
Meiosis
Mitosis
What is Meiosis?
Special cell division for production of gametes
What are some other reasons for genetic variation?
Genetic recombination events
Random crossovers
Independent assortment of alleles/gene variants
Random fertilisation
What are some examples of mutagens?
Pollutants/environmental triggers
Viral insertions
Ultraviolet light
Radiation
What is a mutation?
Any heritable changes to DNA sequence
What is an inconsequential mutation?
A mutation that leads to no net effect on the person
What is an consequential mutation?
A mutation that does have an effect on a person (ranges from milk to severe to lethal)
What is a loss/gain of function variant?
A gene product that either gains or loses some or all of its function
What are the several different mechanism identified in a variant
Single nucleotide variants
Intels (insertion or deletion)
Structural variants
Repeat variants
What is a missense mutation?
a single nucleotide that has been substituted for a different one. The code has been changed so that they could specify a different AA
What is a nonsense mutation?
A single nucleotide has been substituted for a different one. The code has been changed to STOP codon so that AA sequence of resulting proteins is truncated.
What is a translocation?
A chromosomal abnormality
What is an inversion?
Reversal of a genetic coding region
What are copy number variants?
Deletions or duplication of coding region
What are some categories of genetic variations ?
Missense and Nonsense variants
Insertions/Deletions
Single nucleotide variants
What is the process of a blood test for a monogenic disorder?
- take a sample of DNA (usually blood)
- use gene-specific reactions to ‘copy’ the gene
- Separate the ‘copies’ by size
- If there is a gene deletion, the smaller copy will show up
What are the benefits of new sequencing technology?
Much more rapid
Highly automated
Relatively inexpensive
What is bioinformatics?
The analysis, storage, annotation and retrieval of genomic data.
