DNA and Protein Flashcards
Define gene -
A sequence of bases in a DNA molecule that codes for a sequence of amino acids in a protein.
How does a gene code for a protein?
The sequence of bases in the DNA determines the sequence of amino acids in the polypeptide chain - therefore determining the primary structure of the protein.
What is the first stage of protein synthesis?
Transcription
What is RNA?
a polynucleotide
what is RNA made of?
RNA mononucleotides
What reaction holds RNA mononucleotides together?
condensation reactions
RNA polynucleotide and water molecules are formed
held together by phosphodiester bonds.
what is the sugar in RNA?
ribose
what base changes in RNA compared to DNA?
Thymine changes to Uracil in RNA
is RNA double or single stranded?
single stranded.
Summary of transcription -
- Helicase enzyme unwinds gene.. breaks hydrogen bonds between the 2 DNA strands and the strands separate.
- RNA nucleotides align with complementary bases on the template strand of DNA - forming hydrogen bonds.
- RNA polymerase joins the RNA nucleotides together via condensation reaction.
4, When mRNA molecule is complete, hydrogen bonds break, allowing the mRNA to detach from DNA. - mRNA leaved nucleus via a nuclear pore.
Where does transcription occur?
nucleus
Where does translation occur?
on a ribosome
Translation summary -
- ribosome attached to mRNA at Strat codon - 2 codons on ribosome
- tRNA molecule with complementary anticodon binds to first codon on mRNA.
- tRNA molecule with complementary anticodon binds to 2nd codon on mRNA
- Each tRNA molecule brings a specific amino acid to the ribosome. The 2 amino acids carried by the tRNA are held together via peptide bond.
- The ribosome moves along the mRNA by one codon so another tRNA molecule can attach. The cycle repeats until a stop codon is reached.
- Then the ribosome detaches from the mRNA, releasing the finished protein.
what does tRNA have on it?
anticodon on one end
correct amino acid on other end.
what is a codon?
3 bases on mRNA
