Protein synthesis

tRNA function

Found in the cytoplasm

Has an anticodon matching the mRNA codon and carries the specific amino acids to the ribosome

rRNA function

Found in the cytoplasm

Combines with protein to create a ribosome

mRNA function

Made in the nucleus and goes to the ribosome

Carries a copy of DNA

Start codon for DNA

TAC

Stop codon for DNA

ATT, ATC, ACT

Transcription to make mRNA

DNA double helix unzips exposing template bases

Free RNA nucleotides pair with exposed bases

RNA polymerase joins them into an mRNA strand

RNA seperates from DNA at the stop codon

mRNA leaves the nucleus through pores

What is pre-mRNA made of

Introns and exons

Introns

Parts of pre-mRNA that don’t code for a protein

Exons

Part of pre-mRNA that code for proteins

What happens if you rearrange exons

You get different versions of mRNA

Spliceosomes

Cut out introns and join the exons

What are spliceosomes made of

snRNPs

What are snRNPs made of

snRNA + proteins

Do stop codons correspond to an amino acid

No

tRNA structure

A clover leaf’s shape with hydrogen bonds between complementary base pairs

Has a anticodon loop carrying an anticodon

Has a binding site for a specific amino acid

mRNA features

Length depends on the gene

No hydrogen bonds

Linear strand

mRNA and tRNA similarities

Both have bases G,U, A,C

Both made of RNA

Both are a single strand

Both have phosphodiester bonds between nucleotides

Translation process

tRNA carrying a specific amino acids arrive at the ribosome and align alongside mRNA

tRNA anticodon pairs with its complementary mRNA codon held together by hydrogen bonds between bases

As amino acids line up, peptide bonds form between them

Ribosomes hold mRNA and tRNA together and drive the process along

Polysomes

Group of several ribosomes attached to one mRNA strand allowing to mass-produce the same polypeptide rapidly

Rough endoplasmic reticulum (polysomes

A membrane bound organelle responsible for protein synthesis