Protein Synthesis

really? a test the day before break?? 🙄

mRNA (messenger)

copies the DNA code (recipe for protein), during transcription, single stranded, linear, carries DNA code to ribosomes

tRNA (transfer)

reads the message from mRNA, carries the correct amino acid to the ribosome to make the protein (getting what the message is asking for), single stranded, clover/leaf

rRNA (ribosomal)

combines with the proteins to make ribosomes (ribosomes make proteins), single stranded, globular

protein synthesis

process of making proteins from DNA

steps of protein synthesis

1. transcription
2. RNA processing
3. translation

proteins

monomer: amino acid, polymer: polypeptide, function: structure, storage, defence, transport, and enzymes (speed up chemical reactions), homeostasis: builds your structure, helps defend your body and keep it safe

transcription

DNA has to be protected in the nucleus, so the mRNA takes it place to go out

transcription steps

1. initiation
2. elongation
3. termination

initiation

how the cell starts transcription, opens the DNA to get a template strand, searches for promoter region, TATA box

TATA box

region where the transcription begins, RNA polymerase binds at these final steps, helps the enzyme figure out where to bind to the strand

elongation

RNA polymerase adds complementary RNA nucleotides to the DNA template once it has bound to the TATA box (resulting in sing stranded mRNA molecule), uses DNA as its template strand, moves 3’ to 5’, only needs to make one strand, no fragments

termination

finishing the process, RNA hits the termination sequence (indicates the end so it slows down), after about 30 more base pairs it stops

introns

non-coding portions, stays in the nucleus, doesn’t need the whole chromosome

exons

coding sections, exits the nucleus, gets turned into proteins

RNA processing

5’ GTP cap is added to the end of mRNA, adds poly-a-til to other end

cleaving of introns

snRNAs act as scissors and cut out the introns then stick the exons back in

messages

mRNA reads in sets of 3 (triplets)

codons

name for each triplet that responds to an amino acid

translation

happens in cytoplasm, brings the correct amino acid (peptide bonds connects the amino acids together (polypeptide chains)

silent mutation

doesn’t change the amino acid, only switches one of the base pairs

missense mutation

does change the amino acid, only changes 1, can sometime change the shape

nonsense

creates a stop condon too early, doesn’t make the rest of the protein, non-functional protein

frameshift insertion

inserts a nucleotide when it’s not supposed to, changes all of the triplets after the mutation, non-functional protein

frameshift deletion

deletes a nucleotide, changes everything after it, non-functional protein