Protein Synthesis Flashcards
1
Q
What is a codon?
A
Three bases which code for a specific amino acid
2
Q
Where is DNA?
A
The nucleus
3
Q
Where is mRNA?
A
Moves from the nucleus to the ribosomes where proteins are synthesised in the cytoplasm
4
Q
How is protein produced?
A
Dependent on the sequence of bases in the mRNA, if the sequence changes, a different protein will be made
5
Q
How many naturally occurring amino acids are there?
A
20
6
Q
How do cells express with genes?
A
Converting the genetic message into protein, this process of protein synthesis occurs in two stages - transcription and translation
7
Q
How is DNA coped or transcribes into mRNA?
A
- The two strands of DNA helix are unzipped by breaking the weak hydrogen bonds between base pairs. This unwinding of the helix is caused by an enzyme (helicase)
- The enzyme RNA polymerase attaches to the DNA just before the gene
- RNA polymerase move along the DNA strand. Free RNA nucleotides are attracted to (and form hydrogen bonds with) exposed DNA strand nucleotides by complementary base pairing
- RNA polymerase then catalyses the formation of covalent bonds between the RNA nucleotides to form a strand of mRNA
8
Q
How does translation occur?
A
- mRNA strand travels through cytoplasm and attaches to the ribosomes
- For every three mRNA bases, the ribosome lines up one complementary molecules of tRNA
- tRNA molecules transport specific amino acids to the ribosome. The ribosome allow two tRNA molecules to sit next to each other; the ribosomes catalyses the formation of a covalent (polypeptide) bond between two amino acids
- Used tRNA molecules exit the ribosome and collect another specific amino acid
- A chain of several hundred amino acids forms in the correct order according to the original DNA is then made. This is called a poly peptide.
9
Q
What is an anticodon?
A
The complementary three bases on the tRNA
