Genetic control Flashcards
1
Q
Where does protein synthesis occur?
A
In the cell cytoplasm, so DNA is transcribed into mRNA which is small enough to leave the nucleus and enter the cytoplasm
2
Q
What is the genetic code?
A
The sequence of nucleotide bases
3
Q
What is a codon?
A
A triplet of bases on the mRNA, which codes for a single amino acid
4
Q
What is a degenerate code?
A
Most amino acids have more than one codon which codes for them
5
Q
What is a stop codon?
A
Do not code for an amino acid and instead mark the end of a polypeptide chain
6
Q
What does non-overlapping mean?
A
Each base in only read once
7
Q
What is mRNA?
A
- Manufactured when DNA forms a mirror copy of one of its strands
- Suited for its purpose as it contains the correct sequence of triplets to code for specific polypeptides
- Easily broken down so exists only when needed to produce a specific protein
8
Q
What is tRNA?
A
- Single stranded chain folded into a clover-leaf shape
- Several types, each of which carries a specific amino acid
- Contains an anticodon which allows it to pair with complementary bases on mRNA
9
Q
What occurs in polypeptide synthesis?
A
- DNA provides instructions in long sequence of nucleotides and bases they possess
- Complementary section of part of this sequence is made in form of pre-mRNA during transcription
- Pre-mRNA undergoes splicing to form mRNA
- mRNA used as a template to which complementary tRNA molecules attach
- The amino acids carried by tRNA linked to form a polypeptide during translation
10
Q
What occurs in transcription?
A
- DNA helicase breaks down
