3.10 protein synthesis Flashcards
what strand of DNA runs from 5’ to 3’
the sense strand
what strand of DNA runs from 3’ to 5’
the antisense strand
what are the two main stages of protein synthesis
transcription and translation
what is transcription
Process of copying sections of DNA base sequence to produce mRNA so that genetic information can be transported out of the nucleus via nuclear pores to the site of protein synthesis
where does transcription occur
in the nucleus
where does transcription occur
in the nucleus
what are the steps of the transcription of DNA in protein synthesis
1.DNA helix unwinds DNA-Helicase easily breaks weak hydrogen bonds between complementary DNA bases (adenine and thymine 2 & cytosine and guanine 3)
2.Free nucleotides align with exposed bases by complementary base pairing
(purines adenine and guanine with pyrimadines thymine and cytosine)
.(antisense strand used as template, 3’ to 5’ direction for continuous joining of bases)
3.Adjacent nucleotides joined using phosphodiester bonds using RNA polymerase, forming mRNA
4.mRNA moves out of nucleus via nuclear pore to ribosome
which strand is used as the template in transcription
the antisense strand (3’ to 5’)
what is translation
Process by which mRNA is decoded by tRNA into sequence of amino acids.
Occurs at ribosome.
where does translation occur
ribosomes
what are the steps in which mRNA is translated by a ribosome
1.mRNA attaches to ribosome
2.Read in triplet codons, each corresponding to an amino acid.
- Complementary tRNA anticodon attaches to mRNA, bringing corresponding amino acid.
4.Adjacent amino acids joined using peptide bonds by peptidyl transferase. tRNA released by ribosome.
5.Repeated until stop codon reached.
6.Polypeptide has formed.
what’s the structure of tRNA
it’s clover shaped
and it contains a triplet anticodon, which is complementary to mRNA
what are the 3 types of RNA present in a cell
mRNA (messenger) - copies gene from DNA so that genetic information can move out of nucleus. Translated by ribosome.
tRNA (transfer) - clover shaped. carries corresponding amino acids to ribosome by binding using triplet anticodon.
rRNA (ribosomal) - forms ribosome. (protein + rRNA ⟶ ribosomal subunit)
what two types of RNA do ribosomes act as the binding site for
mRNA and tRNA
what’s the enzyme used to join adjacent nucleotides in transcription
RNA polymerase
