Genetics + disease Flashcards
What is a general overview of translation + the steps involved in this process
Occurs in a ribosome located in the cytosol
Univeral code of codons used
ribosome = rRNA + proteins
tRNA to carry amino acid specific to its anticodon
initiation: mRNA binds to ribosome + methionnine tRNA corming initiation complex
elongation: Ribosome moves down the mRNA attaching corrosponding amino acid to polypeptide
termination: when a stop codon is reached the initiatio complex dissociates leading peptide to undergo folding + post translational modification
What is a codon + codon redundancy
A three base sequence corrosponding to an amino acid
4 base pairs and 20 amino acids needs to code for + 3 stop codon
4^3 = 64 = extra combinations gives codon redundance, some amino acids have multiple codons coding for them
What is genetic variation and why is it required
variation in the genomic sequence between members of the same species
enables:
- adaptation to envrionment + changes to envrionment
- tell individuals appart
How much genetic variation is in humans
0.1% different,
6 billion BP
6 million differences between individuals
What are the different ways of classifying genetic variation
lentgh of squence = short long
Style of variant = repeated varients or 1 off
location of variant = where in gene
What are the types of varients caused by SNPs and InDels
SNPs:
synonymous change = forms same amino acid
missence change = change in amino acid
nonsence change = changed to shop codon = truncated
InDels:
Inframe varients:
- Insertion of 3 BP = added AA
- Deleation of 3 BP = deleated AA
Frameshift varients:
- addition or deleation of a non multiple of 3 BP = changes all future amino acids
What are the factors which determine he effects of a missence varient
Chemical simlarities of the two amino acids
Where in the protein the amino acid is located
Does it break an essential secondary structure
Importance of the function of the protein
A miss sence mutation in hemoglobin causes Methaemoglobinaemia why is this change so significant
H64Y
hisE7 - located in the active site
- prevents oxydation of Fe2+ + coordinates oxygen for reverabily reaction
changed to tyrosine:
no longer has the ability to prevent oxydation
- Fe3+ iron atom in beta chain = cannt bind to O2
reduces oxygen capactity
What are the factors which determine how impactful a variation will be
How important is the function of the protein
Can annother protein forfill the changed role of the protein
Amount of protein required for function
- sometimes can be compensated by 2nd allele, sometimes 2 alleles worth of protein required
