gene expression Flashcards
Describe the process of protein synthesis
A gene is part of a DNA molecule that makes up a chromosome. A gene is written in nucleotides as in TAGCCA and so on. DNA is double-stranded but only the template strand is used the other strand the coding strand is used for DNA replication and mutation correction. The enzyme RNA polymerase uses the template strand to make the complementary molecule mRNA by following the base pairing rule as in A-U C-G. This is called transcription. The mRNA but not the DNA is then transported out of the nucleus. A ribosome made up of ribosomal RNA=rRNA clamps down onto the mRNA at the AUG end. A ribosome a reading frame reads the mRNA in threes called a codon. It pauses and a delivery vehicle arrives called tRNA.It arrives with the specific amino acid to the three nucleotides sticking out of one called an anticodon. This process is called translation it continues as the ribosome reads the mRNA a codon at a time while the tRNA deposits the amino acid in the right sequence (this sequence will determine the protein shape and it’s function.) The process continues until a stop codon is released like UGA and the polypeptide is released.
Metabolic pathway
Set of enzyme catalysed reactions where the product from one reaction acts as the substrate for the next.
Redundancy of the cude
64 codons for 20 amino acids
Mutation
permanent change in the base sequence of DNA
Mutagens
Something that cause a mutation like x-ray machines
Substitution mutation
Involve swapping a of nucelotide. Can be either mis-sense, non-sense, same sense. Mis-sense amino acid sequence is changed. Same-same amino acid sequence remains the same due to the redundancy in the code. Non-sense is when a stop codon appears by chance and protein too short.
Insertion and deletion
Is when nucleotides are added or removed by accident. That has an effect by alternating all codons. From this point on, the ribosome reads the codons in threes. This causes a reading frame shift, which can lethal of the protein is desired as the protein won’t be produced.
