Lecture 16 Flashcards
Where does translation occur?
In the cytoplasm
What carries out translation?
The ribosomes
What are ribosomes?
Complex structures made of protein and rRNA that work like enzymes to catalyse protein synthesis
What are the four nucleobases in DNA
Adenine, cytosine, guanine and thymine
What are the four nucleobases in RNA
Adenine, cytosine, guanine and uracil
How many amino acids are there?
20
How is DNA read?
In sets of three called codons
What is the universal genetic code?
The common codon system across all life
What is tRNA?
Transfer RNA
What does tRNA do?
Reads the mRNA
What does the tRNA contain?
An anti-codon, and an amino acid attachment site
Why is the codon/anticodon pairing and amino acid attached so spesific?
To ensure the same mRNA sequence is always translated the same way to make the same protein
What are the three steps of translation?
Initiation, elongation, termination
What happens during initiation?
The ribosome, mRNA, and the first tRNA come together to form the translation initiation complex. The first tRNA always codes for met (AUG/Start)
What happens during elongation?
The ribosome moves along the mRNA, adding amino acid to the growing peptide chain
What happens during termination?
A ‘stop codon’ indicates the peptide chain has all the necessary amino acids and causes the translation complex to break apart releasing the newly formed peptide chain ready for protein folding and post-translational modification
What is the codon redundancy?
There are 64 possible codons and 20 amino acids plus ‘stop’ therefore each amino acid can be coded for by multiple codons (except met and trp)
What is the advantage of codon redundancy?
It allows for some flexibility in the gene sequence, without changing the protein
What is genetic variation?
Differences between the same locations of DNA sequences of members of the same species. This forms alleles
How different are humans to each other on sequence level?
0.1%
Why is genetic variation important?
To help us determine who is who, help survival and help organisms to adapt to their environment
What are the three different ways genetic variants can be classified?
Number of DNA bases involved, style of DNA sequence involved, location of the change
What are the two genetic variants we focus on?
SNPs and InDel
What is a SNP?
Single nucleotide polymorphism, a single base change in the DNA sequence
