5.6 - Structure of Ribonucleic Acid Flashcards
What type of molecule transfers the DNA from the nucleus to the cytoplasm via nuclear pores? Also, why can it do this as opposed to DNA?
mRNA. Small enough, as opposed to DNA.
What is the genetic code?
A sequence of nucleotide bases on mRNA.
What is a codon?
A sequence of 3 bases (triplet) that codes for a single amino acid.
Is the genetic code degenerate? What does it mean?
Yes. It means that most amino acids have more than one codon.
Three codons don’t code for any amino acid. What are they?
Stop codons. They mark the end of a polypeptide chain.
The code is non-overlapping. What does this mean?
Each base in the sequence is read only once.
What is a universal code?
It means the same codon codes for the same amino acid in all organisms.
Is RNA a polymer or a monomer?
Polymer. It’s made up of repeating mononucleotide sub-units.
What is each nucleotide in RNA made up of?
- Ribose (a pentose sugar).
- An organic base (ACGU).
- A phosphate group.
What 2 types of RNA feature in protein synthesis?
mRNA & tRNA.
How does the size of mRNA compare to tRNA?
mRNA = thousands of mononucleotides. tRNA = relatively small molecule - around 80 nucleotides.
What is the role of mRNA in the cytoplasm, and how is it suited to this role?
To act as a template for the production of proteins.
Its structure possesses the correct sequences of triplets of organic bases to code for specific polypeptides. Also easily broken down - exists only when needed to synthesis a given protein.
What shape is tRNA?
Single-stranded chain - clover-leaf shape. One end of the chain extends beyond the other.
What is the significance of an extension on one end of the tRNA chain?
It allows an amino acid to attach.
What is an anticodon?
A sequence of three organic bases on tRNA complementary to a codon on an mRNA molecule to attach the two.
