protein synthesis in eukaryotes Flashcards
What does RNA stand for?
Ribonucleic acids.
Compare DNA to RNA.
- DNA contains deoxyribose, whereas RNA, contains ribose sugar.
- DNA contains ACTG, whereas RNA contains ACUG.
- RNA is single stranded, whereas DNA is double stranded.
- DNA is only found in the nucleus, whereas RNA is found in both the nucleus and the cytoplasm.
What is the main function of mRNA?
Responsible for taking the information in DNA, out of the nucleus, to the ribosome.
Describe the process of transcription.
- RNA polymerase, binds to the DNA, and runs along it , thus breaking the hydrogen bonds between the bases, thus leaving us with two exposed strands.
2.RNA polymerase, then adds RNA nucleotides , to the complementary bases to one of the strands.
3.RNA polymerase, then also joins the two nucleotides together , using a condensation reaction, thus forming a phosphodiester bond.
4.Once the RNA strand is complete, the RNA polymerase, and the RNA strand, detach from the DNA, thus leaving behind the original strand of DNA , plus the strand of pre-mRNA.
explain what is meant by splicing.
It is when the cell, removes introns(non-coding regions of DNA), from the pre-mRNA.
A group of proteins cluster around the pre-mRNA, thus removing introns, and then attaching the remaining exons together.
Splicing therefore produces mRNA.
does a prokaryotic cell need splicing?
no, there is no pre-mRNA, therefore no need for splicing.
What is a codon?
A set of 3 bases in mRNA, which code for an amino acid.
What is an anticodon?
Attached to the amino acid, there are 3 bases, which are complementary to the codon on the mRNA.
what is tRNA.
An amino acid, carries an anticodon, which is complementary to the codon, on the strand of mRNA.
The molecule is called tRNA. It is clover shaped.
What shape does tRNA have?
Clover shaped.
Describe the structure of tRNA.
It has an amino acid binding site, base pairs held together by hydrogen bonds, and an anticodon ( 3 bases complementary to the codon on the mRNA strand).
describe translation.
- Ribosome binds to the mRNA strand.
- The tRNA with witch a complementary anticodon, binds to a codon on the mRNA strand, bringing an amino acid with it.
3.This repeats a second Time, with a second molecule.
4.The ribosome then joins together the two amino acids, using a condensation reaction , which forms peptide bonds between amino acids. - The ribosome then moves along the mRNA, until the polypeptide chain is complete. At which point, the ribosome, the polypeptide chain, tRNA, and mRNA, all detach from one another.
what does the condensation reaction in translation, require?
It is catalysed by an enzyme, and it requires ATP energy.
What are the 3 types of RNA?
rRNA, tRNA, mRNA
How are tRNA and rRNA produced?
they are coded by genes, however, they don’t undergo translation, because they have different biological functions, such as helping translating mRNA.
