2.1.3 Protein Synthesis Flashcards
What is RNA made up of?
Nucleotide
A Pentose sugar (ribose) attached to a phosphate group and a base.
Bases: Adenine, Guanine, Cytosine, Uracil
How do RNA nucleotides join together?
A condensation reaction forming a phosphodiester bond
What is the function of RNA
Responsible for taking the info from the DNA, out of the nucleus to the ribosomes.
To synthesise proteins
What is the function of mRNA
Carries info from the DNA and nucleus to the ribosomes for PS
What bond holds together base pairs
Hydrogen bonds
What is the process of transcription?
RNA polymerase breaks the hydrogen bonds between the bases.
Adds RNA nucleotides to the exposed complementary bases on template strand.
Once two nucleoyptides are joined to their bases, RNA polymerase joins them together via a condensation reaction = phosphodiester bond.
Continues to move down the DNA, joining nucleotides to bases.
Once reached the end of the strand, RNA polymerase and pre RNA strand detach.
What do our genes contain?
Coding sequences: introns
Non-coding sequences: exons
What is the process of splicing?
Specific proteins cluster around the pre-mRNA and remove the introns, then attach the exons together.
= mRNA
What is a codon.
A set of three bases in mRNA that code for an amino acid.
3 key features of the genetic code on mRNA
The genetic code on mRNA is:
Degenerate. This means that multiple different codons can code for the same amino acid.
Non-overlapping. This means that there is no overlap between codons when they are read: each part of the triplet is only read once.
Universal. This means that all living organisms use the same genetic code; each triplet codes for the same thing in any organism.
What is an anticodon?
Carries an amino acid with 3 bases complimentary to a codon on mRNA
What is the process of translation?
mRNA strand reaches ribosome and attaches to it.
Inside, there are tRNA molecules (anticodons carrying amino acids.)
A tRNA molecule complementary to the codon on the mRNA strand, binds to it and another tRNA does next to it.
The ribosome joins these two amino acids together via a condensation reaction, forming a peptide bond.
The ribosome moves along, releasing the anticodon from the AA and codon.
Another tRNA molecule binds next to it and another bond is formed= continues.
Once at the end, the ribosome reaches a stop codon then, all detach from each other + polypeptide chain is formed.
What does tRNA do?
Transfers amino acids to the polypeptide chain.
Made up of a single strand of RNA
Has one anticodon found at the bottom of the molecule.
How polypeptides/proteins control physical development of an organism
Structural proteins - keratin, collagen
Hormones
Hox genes - homeobox genes
Transcription factors
