(U8) Transcription + Translation

What is transcription? (generally - big picture)

The process of transforming DnA to mRnA

What are the 3 differences between DnA and RnA

DnA: double helix vs rna single strand

DnA has thymine, rna has uracil

Rna has ribose, dna has deoxyribose

what are exons and introns?

exons: expressed = important (it has to be in the mrna sequence to code for the corect protein)

introns = intervening / between = splice them out to get the correct mrna strand.

what is alternative splicing

multiple gene proteins from the same gene

the primary rana transcript has introns and exons - splicing is cutting out the introns, but alt psplicing is when the cell cna mix and match which exons it wants to include resulting in diff proteins

what happens after transcription

rna leaves the nucleus and finds a ribosome in the cytoplasm or rough endoplasmic reticulum for translation

How does transcription actually work in practice?

Dna is unzipped, rna polymerase constructs a matching side to it, then it goes and finds a ribosome

What are the 3 types of rna

mrna, rrna, trna

What is mrna

messenger rna: made in transcription from dna template strand and carries protein instructions (going from the gene in the nucleus to the ribosome)

What is rrna

ribosomal rrna and makes the “hamburger” structure of ribosomes

What is trna

carries the correct amino acid with the ribosome and has an anticodon which locks with the mrna codon

middle of burger: P side on the left, A site on the right, P site anticodon matches with mrna codon and activates the corresponding amino acid that is attached before exiting the reaction site (through E) and beginning it again

What are codons and anticodons

mrna codons: sets of 3 letters that are translated one at a time

trna.has anticodons: complimentary base pair to codons

How does trna relate to mrna

decodes mrna and gives the correct amino acid (ex: if the codon codes for lucine with AGA, the trna anticodon has UCU and lucine on its other side which gets activated and then added to the amino acid chain

What are frameshift mutations

insertion or deletions which shift over the reading frame

example: [the cat ate the rat] → [the ata tet her at]

What are the 3 types of substitution or point mutations

silent, missense, nonsense

What are silent mutations

changing on e part of the codon but it still results in the same amino acid

example; ata gets changed to aga, but they are still both lucine

What is missense

1 amino acid gets changed as a reuslt of a change in one letter of the codon

can be meh: hydrophobic → hydrophobic

or suck: ex. hydrophobic → hydrophilic = protein doesnt fold properly (ex: sickle sell anemia and hemoglobin)

What is nonsense

Turns an early-sequence codon into a STOP codon = missing TONS of amino acids you would have had