RNA and Protein Synthesis 4A Flashcards
1
Q
Two types of RNA
A
Messenger RNA and Transfer RNA
2
Q
Messenger RNA function
A
Made during transcription carries genetic code from DNA to ribosomes where it is used to make a protein during translation
Single polynucleotide strand
3
Q
Transfer RNA function
A
Involved during translation carries amino acids to ribosomes
Single polynucleotide strand
Animo acid binding site at one end and three bases called an anticodon
4
Q
Describe transcription
A
- RNA polymerase attaches to DNA double helix at the start of the gene
- In eukaryotes hydrogen bonds are broken down by DNA helicase attached to the RNA polymerase this separates the strands and leave some bases exposed
One of the strands is used as a template to make an mRNA copy
The RNA polymerase lines up free RNA alongside the exposed bases the free nucleotides are then attracted to exposed bases
Specific base pairing occurs and they are joined by RNA polymerase
RNA polymerase moves along the strand hydrogen bonds reform and the strands coil back into a double helix
5
Q
Define splicing
A
introns are removed and exons are joined together forming mRNA strands
6
Q
Describe translation
A
- mRNA attaches to a ribosome and tRNA molecules carry amino acids to it
ATP provides the energy for the bond between the amino acid and the tRNA molecule to form
A tRNA molecule with an anticodon complementary to the first codon on the mRNA attaches by complementary base pairing
A second tRNA molecule attaches to the next codon on the mRNA in the same way
The two amino acids attached to the tRNA molecule are joined by a peptide bond, the first molecule moves away leaving its amino acid behind
A third tRNA molecule binds to the next codon on the mRNA its amino acid binds to the first two and the second tRNA molecule moves away
Process continues until there’s a stop signal on the mRNA molecule
polypeptide moves away from ribosome and translation is complete
